WO2018010074A1 - Optical signal transmitter and receiver, and transmission method and system - Google Patents

Abstract

An optical signal transmitter (101) and receiver (104), and a transmission method and system, relating to the field of laser communications and used for solving the problem that a transmission distance in a direct detection system is affected by dispersion. The optical signal transmitter (101) comprises: an optical splitter (1011), a modulator (1012), a wavelength-related phase shifter (1013) and an optical coupler (1014).

Description

Optical signal transmitter, receiver, transmission method and system Technical field

The present invention relates to the field of laser communication, and in particular, to an optical signal transmitter, receiver, transmission method and system.

Background technique

In the long-distance transmission laser communication system, a coherent detection system using coherent optical transmission technology is generally adopted, a polarization-multiplexed complex electric field signal is transmitted at the transmitting end, and coherent reception is used at the receiving end to recover the complex electric field emitted by the transmitting end. signal. Specifically, the receiving end ODSP (English full name: optical digital signal processing, Chinese full name: optical digital signal processing) can compensate the dispersion of the fiber link, PMD (English full name: polarization mode dispersion, Chinese full name: polarization mode dispersion), LOFO (English full name: local oscillator frequency offset, Chinese full name: local oscillator frequency offset), but such systems are costly, system margin is too large, there have been design problems.

In the laser communication system transmitted in the metropolitan area, the usual transmission distance is only a few hundred kilometers. If the coherent detection system is used, the cost is too high. Therefore, a direct detection system is currently developed, and the cost is relatively low. The direct detection system means that the transmitter carries information in the optical signal through light intensity modulation. The receiver directly converts the light intensity modulated signal into an electrical signal through the photodetector, and then detects the electrical signal to recover the original signal. However, in the direct detection system, the transmission distance is affected by the dispersion. If the dispersion compensation is not added, the transmission distance is generally limited to 80 km, and the rate is limited.

Summary of the invention

Embodiments of the present invention provide an optical signal transmitter, receiver, transmission method, and system for solving the problem that the transmission distance in a direct detection system is affected by dispersion.

In order to achieve the above object, embodiments of the present invention adopt the following technical solutions:

In a first aspect, an optical signal transmitter is provided, the optical signal transmitter comprising:

An optical splitter for coupling the first continuous light and the second continuous light to generate a first multiplexed continuous light and a second multiplexed continuous light, wherein the wavelength of the first continuous light and the second continuous light The wavelength of the first multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light;

a modulator for modulating the same data signal of the first continuous light component and the second continuous light component of the first multiplexed continuous light generated by the optical splitter to generate a load optical signal;

a wavelength-dependent phase shifter for phase shifting π/2 according to one continuous light of the second multiplexed continuous light generated by the optical splitter, and phase shifting the second multiplexed continuous light One continuous light and another continuous light output without phase shifting as a phase shifted optical signal;

An optical coupler for coupling a load light signal generated by the modulator and a phase shift light signal generated by a wavelength dependent phase shifter to generate an outgoing light signal, wherein the outgoing light signal includes a first outgoing light signal and a second outgoing light The signal, the wavelength of the optical carrier of the first outgoing optical signal is different from the wavelength of the optical carrier of the second outgoing optical signal, and the phase difference between the data signal carried by the first outgoing optical signal and the data signal carried by the second outgoing optical signal is π/ 2. The first outgoing optical signal is used to be converted by the optical signal receiver into a first outgoing electrical signal R _I , and the second outgoing optical signal is used to be converted by the optical signal receiver into a second outgoing electrical signal R _Q , the first outgoing electrical The signal R _I and the second outgoing electrical signal R _{Q are} used to obtain a data signal modulated in the outgoing optical signal by performing digital signal processing on the R _I +j*R _Q DSP.

The optical signal transmitter provided by the present invention comprises an optical splitter, a modulator, a wavelength dependent phase shifter and an optical coupler. The first continuous light and the second continuous light having different wavelengths are input, and are divided into a first multiplexed continuous light and a second multiplexed continuous light after passing through the optical splitter, wherein the first multiplexed continuous light includes the first a component of continuous light and a component of second continuous light, and the second multiplexed continuous light comprises a component of the first continuous light and a component of the second continuous light; and then one of the branch routing modulators multiplexes the first channel The first continuous light and the second continuous light in the continuous light modulate the same data signal to generate a loaded optical signal; the other branch routing wavelength dependent phase shifter selects one continuous light in the second multiplexed continuous light according to the wavelength Shifting π/2, then using the phase-shifted one continuous light and the other unphase-shifted continuous light output in the second multiplexed continuous light as the phase-shifted optical signal; finally, the optical coupler will load the optical signal and The phase-shifted optical signal is coupled to generate an outgoing optical signal, wherein the outgoing optical signal includes a first outgoing optical signal and a second outgoing optical signal having different wavelengths, and the data signals carried by the first outgoing optical signal and the second outgoing optical signal However, with a phase difference of π / 2. Such a first outgoing optical signal is converted by the optical signal receiver into a first outgoing electrical signal R _I , and the second outgoing optical signal is converted by the optical signal transmitter into a second outgoing electrical signal R _Q , which is detected by the optical signal receiver by coherent detection In the technique, the formula R _I +j*R _{Q of the} complex signal is recovered, and then the digital signal processing of R _I +j*R _Q can be restored to obtain the data signal modulated in the outgoing optical signal. Since the first outgoing optical signal and the second outgoing optical signal retain the phase signal of the data signal, the coherent detection technique is well utilized to recover the original data signal, and thus is not limited by dispersion, and can be applied to the far as the coherent detection system. The distance transmission solves the problem that the transmission distance in the direct detection system is affected by the dispersion. In addition, since the optical signal transmitter and the optical signal receiver provided by the present invention constitute a direct detection system, the cost is low.

In a possible design, the wavelength-dependent phase shifter is a straight waveguide, wherein the length of one straight waveguide satisfies: the frequency difference between the first continuous light and the second continuous light forms a phase difference when the traveling wave propagates in a straight waveguide It is π/2.

In one possible design, the wavelength dependent phase shifter includes:

a first wavelength division multiplexer, configured to decompose the second multiplexed continuous light into a first optical path signal and a second optical path signal;

a phase shifter for phase shifting the second optical path signal outputted by the first wavelength division multiplexer such that the phase of the first optical path signal and the second optical path signal are different by π/2;

And a second wavelength division multiplexer for multiplexing the first optical path signal output by the first wavelength division multiplexer and the phase shifted second optical path signal output by the sub-phase shifter to generate a phase-shift optical signal.

In one possible design,

The first wavelength division multiplexer and the second wavelength division multiplexer are optical cross-wavelength division multiplexers interlever; or the first wavelength division multiplexer is interlever and second wavelength division multiplexing The device is a wavelength selective switch WSS; or, the first wavelength division multiplexer is WSS and the second wavelength division multiplexer is interlever; or the first wavelength division multiplexer and the second wavelength division multiplexer are WSS; or The first wavelength division multiplexer and the second wavelength division multiplexer are wavelength division multiplexing couplers WDMC.

When the first wavelength division multiplexer adopts interlever or WSS, since the second multiplexed continuous light passes through the first wavelength division multiplexer, it is divided into two parity optical signals and is independent of the wavelength of the input optical wave, so when the input optical wave is input It is not necessary to adjust the first wavelength division multiplexer according to the wavelength of the input light wave every time the wavelength changes. When the first wavelength division multiplexer or the second wavelength division multiplexer uses WDMC, the fabrication is simple and the theoretical insertion loss is small.

In one possible design, the wavelength dependent phase shifter is an all-pass type microring structure, and the all-pass type microring structure includes:

a microring resonator MRR for causing a resonant continuous light of the second multiplexed continuous light to pass through the resonant continuous light to generate a π/2 phase shift;

A straight waveguide for passing resonant continuous light of the MRR output and another non-resonant continuous light of the second multiplexed continuous light.

In one possible design, the modulator is biased at the carrier suppression point.

第二路复用连续光的电磁场表示形式为

或者，第一路复用连续光的电磁场表示形式为

第二路复用连续光的电磁场表示形式为

其中，

为第一连续光的分量，

为第二连续光的分量。In one possible design, the electromagnetic field of the first representation as continuous light E _1, the second continuous light field representation is E _2, the first multiplexing the continuous light field representation as

The electromagnetic field representation of the second multiplexed continuous light is

Alternatively, the electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

among them,

Is the component of the first continuous light,

It is the component of the second continuous light.

In a second aspect, an optical signal receiver is provided, the optical signal receiver comprising:

a wave decomposition multiplexer for receiving an outgoing optical signal and decomposing the first outgoing therefrom The optical signal and the second outgoing optical signal, the wavelength of the optical carrier of the first outgoing optical signal is different from the wavelength of the optical carrier of the second outgoing optical signal, and the data signal carried by the first outgoing optical signal and the second outgoing optical signal are carried The phase of the data signal differs by π/2;

a first photodetector for converting the first outgoing optical signal into a first outgoing electrical signal R _I ;

a second photodetector for converting the second outgoing optical signal into a second outgoing electrical signal R _Q , wherein the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q are} used to pass R _I +j* R _Q performs digital signal processing on the DSP and then restores the data signal modulated in the outgoing optical signal.

The wave decomposition multiplexer can also be implemented using an interlever to ensure that it is independent of the wavelength of the outgoing optical signal emitted by the optical signal transmitter.

The optical signal receiver provided by the invention comprises a wave decomposition multiplexer, a first photodetector and a second photodetector. After receiving the optical signal sent by the optical signal transmitter, the optical signal receiver decomposes it into a first outgoing optical signal and a second outgoing optical signal by a wave decomposition multiplexer; then the first photodetector will be the first The outgoing optical signal is converted into a first outgoing electrical signal R _I , and the second outgoing optical signal is converted by the second photodetector into a second outgoing electrical signal R _Q . The optical signal receiver passes the formula R _I +j*R _Q of the recovered complex signal in the coherent detection technique, and then digitally processes the R _I +j*R _Q to obtain the data signal modulated in the outgoing optical signal. . Since the first outgoing optical signal and the second outgoing optical signal retain the phase signal of the data signal, the coherent detection technique is well utilized to recover the original data signal, and thus is not limited by dispersion, and can be applied to the far as the coherent detection system. The distance transmission solves the problem that the transmission distance in the direct detection system is affected by the dispersion. In addition, since the optical signal transmitter and the optical signal receiver provided by the present invention constitute a direct detection system, the cost is low.

In one possible design, the outgoing optical signal is generated by the optical signal transmitter in the following manner:

The optical signal transmitter couples the first continuous light and the second continuous light to generate first multiplexed continuous light and second multiplexed continuous light, wherein the wavelength of the first continuous light is different from the wavelength of the second continuous light The first multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light;

The optical signal transmitter modulates the same data signal with the first continuous light component and the second continuous light component of the first multiplexed continuous light to generate a loaded optical signal;

The optical signal transmitter phase shifts π/2 according to one wavelength of the second multiplexed continuous light, and multiplexes the phase shifted one continuous light and the other unphase shifted in the second multiplexed continuous light Continuous light output as a phase shifted optical signal;

The optical signal transmitter couples the loaded optical signal and the phase shifted optical signal to generate an outgoing optical signal.

In a third aspect, an optical signal transmission method is provided, the method comprising:

Coupling the first continuous light and the second continuous light to generate first multiplexed continuous light and second multiplexed continuous light, wherein the wavelength of the first continuous light is different from the wavelength of the second continuous light, the first path The multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light;

Modulating the same data signal for the component of the first continuous light and the component of the second continuous light in the first multiplexed continuous light to generate a loaded optical signal;

Selecting one continuous light in the second multiplexed continuous light to phase shift by π/2 according to the wavelength, and multiplexing the phase-shifted one continuous light and the other unphase-shifted continuous light output in the second multiplexed continuous light As a phase shifted optical signal;

Combining the loaded optical signal and the phase-shifted optical signal to generate an outgoing optical signal, wherein the outgoing optical signal comprises a first outgoing optical signal and a second outgoing optical signal, a wavelength of the optical carrier of the first outgoing optical signal and a second outgoing light The wavelength of the optical carrier of the signal is different, and the data signal carried by the first outgoing optical signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2, and the first outgoing optical signal is used to be converted into the first by the optical signal receiver. R _I a radio signal, the second outgoing light signals for conversion from the optical signal receiver of the second radio signal R _Q, R _I of the first radio signal and the second electrical signal emitted by a R _Q R _I +j*R _Q performs digital signal processing on the DSP and then restores the data signal modulated in the outgoing optical signal.

The optical signal transmission method in the embodiment of the present invention can be applied to the above-mentioned optical signal transmitter. Therefore, the technical effects of the present invention can be referred to the optical signal transmitter.

第二路复用连续光的电磁场表示形式为

或者，第一路复用连续光的电磁场表示形式为

第二路复用连续光的电磁场表示形式为

其中，

为第一连续光的分量，

为第二连续光的分量。In one possible design, the electromagnetic field representation of the first continuous light is E ₁ and the electromagnetic field representation of the second continuous light is E ₂ , and the electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

Alternatively, the electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

among them,

Is the component of the first continuous light,

It is the component of the second continuous light.

In a fourth aspect, an optical signal transmission method is provided, where the optical signal transmission method includes:

Receiving an outgoing optical signal and decomposing the first outgoing optical signal and the second outgoing optical signal therefrom, wherein a wavelength of the optical carrier of the first outgoing optical signal is different from a wavelength of the optical carrier of the second outgoing optical signal, and the first outgoing optical signal carries The data signal is opposite to the phase of the data signal carried by the second outgoing optical signal by π/2;

Converting the first outgoing optical signal into a first outgoing electrical signal R _I ;

Converting the second outgoing optical signal into a second outgoing electrical signal R _Q , wherein the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q are} used for digital signal processing of the DSP by R _I +j*R _Q The data signal modulated in the outgoing optical signal is restored.

The optical signal transmission method in the embodiment of the present invention can be applied to the above-mentioned optical signal receiver. Therefore, the technical effects of the present invention can be referred to the optical signal receiver.

In one possible design, the outgoing optical signal is generated by the optical signal transmitter in the following manner:

An optical signal transmitter couples the first continuous light and the second continuous light to generate a first The multiplexed continuous light and the second multiplexed continuous light, wherein the wavelength of the first continuous light is different from the wavelength of the second continuous light, the first multiplexed continuous light comprising a component of the first continuous light and a second continuous light a component, and the second multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light;

The optical signal transmitter modulates the same data signal with the first continuous light component and the second continuous light component of the first multiplexed continuous light to generate a loaded optical signal;

The optical signal transmitter phase shifts π/2 according to one wavelength of the second multiplexed continuous light, and multiplexes the phase shifted one continuous light and the other unphase shifted in the second multiplexed continuous light Continuous light output as a phase shifted optical signal;

The optical signal transmitter couples the loaded optical signal and the phase shifted optical signal to generate an outgoing optical signal.

In a fifth aspect, a direct detection system is provided, comprising the optical signal transmitter of the first aspect and the optical signal receiver of the second aspect.

Since the direct detection system in the embodiment of the present invention includes the above-mentioned optical signal transmitter and optical signal receiver, the technical effects that can be obtained can also be referred to the above-mentioned optical signal transmitter and optical signal receiver, and the embodiment of the present invention is here. No longer.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any creative work.

1 is a schematic structural diagram of a direct detection system according to an embodiment of the present invention;

2 is a schematic structural diagram of an optical signal transmitter according to an embodiment of the present invention;

3 is a schematic structural diagram of a wavelength-dependent phase shifter according to an embodiment of the present invention;

4 is a schematic structural diagram of another wavelength-dependent phase shifter according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of still another wavelength-dependent phase shifter according to an embodiment of the present invention; FIG.

FIG. 6 is a schematic structural diagram of an optical signal receiver according to an embodiment of the present invention;

FIG. 7 is a schematic flowchart diagram of an optical signal transmission method according to an embodiment of the present invention;

FIG. 8 is a schematic flowchart diagram of another optical signal transmission method according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The present invention provides a direct detection system, as shown in FIG. 1, comprising: a transmitter 101, a multiplexer 102, a demultiplexer 103, and a receiver 104. The transmitter 101 receives the continuous light of the wavelengths λ ₁ and λ ₂ respectively, and the outgoing optical signal output by the transmitter 101 passes through the multiplexer 102 and transmits through the optical fiber, and the demultiplexer 103 receives the outgoing optical signal and transmits it to the corresponding signal. The receiver 104 extracts two electrical signals R _I and R _Q from the outgoing optical signal by the receiver 104.

The optical signal transmitter, the receiver, the transmission method and the system provided by the invention pass the first continuous light and the second continuous light with different input wavelengths through the optical signal transmitter, and are divided into the first way multiplexing after passing through the optical splitter. Continuous light and second multiplexing multiplexed light, wherein the first multiplexed continuous light comprises a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light comprises a component of the first continuous light a component of the second continuous light; and then one of the branch routing modulators modulates the same data signal for the first continuous light and the second continuous light of the first multiplexed continuous light to generate a loaded optical signal; The correlation phase shifter selects one continuous light in the second multiplexed continuous light to phase shift by π/2 according to the wavelength, and then multiplexes the phase shifted one continuous light and the other unphase in the second multiplexed continuous light. The shifted continuous light output is used as a phase-shifted optical signal; finally, the optical coupler couples the loaded optical signal and the phase-shifted optical signal to generate an outgoing optical signal, and the outgoing optical signal includes a first outgoing optical signal having a different wavelength and a first Emit an optical signal, a first data signal and the outgoing optical signal and the second outgoing optical signal carried by the same but the phase difference of π / 2. Such a first outgoing optical signal is converted by the optical signal receiver into a first outgoing electrical signal R _I , and the second outgoing optical signal is converted by the optical signal transmitter into a second outgoing electrical signal R _Q , which is passed by the optical signal receiver The formula R _I +j*R _Q for recovering the complex signal in the detection technique is then digitally processed by R _I +j*R _Q to obtain the data signal modulated in the outgoing optical signal. Since the first outgoing optical signal and the second outgoing optical signal retain the phase signal of the data signal, the coherent detection technique is well utilized to recover the original data signal, and thus is not limited by dispersion, and can be applied to the far as the coherent detection system. The distance transmission solves the problem that the transmission distance in the direct detection system is affected by the dispersion.

The present invention provides an optical signal transmitter, as shown in FIG. 2, comprising: an optical splitter 1011, a modulator 1012, a wavelength dependent phase shifter 1013, and an optical coupler 1014. among them:

The optical splitter 1011 is configured to couple the first continuous light and the second continuous light to generate a first multiplexed continuous light and a second multiplexed continuous light, wherein the wave of the first continuous light and the second continuous The wavelength of the light is different, the first multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light.

Exemplarily, referring to FIG. 2, the first continuous light wavelength is λ ₁ , the second continuous light wavelength is λ ₂ , λ ₁ and λ ₂ can be configured to be 50 GHz apart, and the optical splitter 1011 can be optically separated. wave, twice the input interval of λ ₁ and λ ₂ intervals, for example 100GHz. Further, λ ₁ and λ _{2 do} not have to be generated by one laser, and a symmetrical two continuous lights λ ₁ and λ ₂ can be generated by carrier modulation by a laser having a wavelength of λ ₀ .

Electromagnetic field after the first continuous signal light enters the optical transmitter 101 in the format of E _1, after the second continuous light enters the electromagnetic field of the optical signal transmitter 101 in the format of E _2.

时，第二路复用连续光的电磁场表示形式为

当第一路复用连续光的电磁场表示形式为

时，第二路复用连续光的电磁场表示形式为

其中，

为第一连续光的分量，

为第二连续光的分量。The first multiplexed continuous light and the second multiplexed continuous light are generated after multiplexing by the optical splitter 1011. The first multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light also includes a component of the first continuous light and a component of the second continuous light. The present invention does not limit the modules in which the first multiplexed continuous light and the second multiplexed continuous light are subsequently connected, and the two can be interchanged. Illustratively, when the electromagnetic characterization of the first multiplexed continuous light is

When the second path multiplexes the continuous electromagnetic field, the representation is

When the electromagnetic physics representation of the first multiplexed continuous light is

When the second path multiplexes the continuous electromagnetic field, the representation is

among them,

Is the component of the first continuous light,

It is the component of the second continuous light.

The modulator 1012 is configured to modulate the same data signal of the first continuous light component and the second continuous light component of the first multiplexed continuous light generated by the optical splitter 1011 to generate a load optical signal.

The modulator 1012 needs to be biased at the carrier suppression point, and the data signal loaded by the first continuous light in the output loading optical signal is the same as the data signal loaded by the second continuous light. The modulator 1012 can be an IQ-MZM (English full name: in-phase quadrature Mach Zehnder modulator, full name: in-phase quadrature Mach Zehnder modulator), in which the emitter needs two electrodes to load the bias voltage T _I and T _{Q respectively.} . Modulator 1012 may be a conventional MZM, the originating case only a load electrode bias T _I.

The wavelength-dependent phase shifter 1013 is configured to phase-shift π/2 according to one continuous light in the second multiplexed continuous light generated by the wavelength selective optical splitter 1011, and multiplex the second multiplex continuously A phase-shifted continuous light in the light and another un-phase-shifted continuous light output serve as phase-shifted light signals.

Wherein, the phase shifting effect of the wavelength dependent phase shifter 1013 on the continuous light is related to the wavelength of the first continuous light or the second continuous light. Illustratively, the wavelength dependent phase shifter 1013 may be related to the wavelength of the first continuous light. The first continuous light in the phase-shifted optical signal generated at this time is phase-shifted by π/2, or the wavelength-dependent phase shifter 1013 may be related to the wavelength of the second continuous light in the second multiplexed continuous light. The second continuous light in the generated phase-shifted optical signal is phase-shifted by π/2, and the final effect is that the phase of the first continuous light and the second continuous light in the generated phase-shifted optical signal is always different by π/2.

The optical coupler 1014 is configured to couple the load optical signal generated by the modulator 1012 and the phase shift optical signal generated by the wavelength dependent phase shifter 1013 to generate an outgoing optical signal, where the outgoing optical signal includes the first outgoing optical signal and the first The second outgoing optical signal, the wavelength of the optical carrier of the first outgoing optical signal is different from the wavelength of the optical carrier of the second outgoing optical signal, and the phase of the data signal carried by the first outgoing optical signal and the second outgoing optical signal The difference is π/2.

The optical carrier of the specific first outgoing optical signal has a phase difference of δ with the carried data signal, and the optical carrier of the second outgoing optical signal is different from the phase of the carried data signal by δ+π/2, wherein δ is the first path The optical path difference of the multiplexed continuous light and the second multiplexed continuous light is performed in the optical coupler 1014 because the path of the first multiplexed continuous light and the path of the second multiplexed continuous light are transmitted and the passing device is different. When the two consecutive lights are coupled, the optical path difference is generated, and the optical carrier reflected on the outgoing optical signal and appearing as the outgoing optical signal has a phase difference δ with the carried data signal. Therefore, the data signal carried by the first outgoing optical signal is the same as the data signal carried by the second outgoing optical signal but with a phase difference of π/2.

The first outgoing optical signal and the second outgoing optical signal are transmitted to the optical signal receiver via optical fiber transmission.

The first outgoing optical signal is used to be converted by the optical signal receiver into a first outgoing electrical signal R _I , and the second outgoing optical signal is used to be converted by the optical signal receiver into a second outgoing electrical signal R _Q , The first outgoing radio signal R _I and the second outgoing electrical signal R _Q are performed by the optical signal receiver on R _I +j*R _Q according to the formula R _I +j*R _Q of the recovered complex signal in the coherent detection technique. After digital signal processing (English full name: digital signal processing, English abbreviation: DSP), the data signal modulated in the outgoing optical signal is restored, and the data signal is retained because the first outgoing optical signal and the second outgoing optical signal are retained. The phase signal makes good use of the coherent detection technology to recover the original data signal, so it is not limited by the dispersion, and can be applied to the long-distance transmission like the coherent detection system, solving the problem that the transmission distance in the direct detection system is affected by the dispersion. . The specific manner is shown in the description of the optical signal receiver shown in FIG. 6, and details are not described herein again.

The optical signal transmitter provided by the present invention comprises an optical splitter, a modulator, a wavelength dependent phase shifter and an optical coupler. The first continuous light and the second continuous light having different wavelengths are input, and are divided into a first multiplexed continuous light and a second multiplexed continuous light after passing through the optical splitter, wherein the first multiplexed continuous light includes the first a component of continuous light and a component of second continuous light, and the second multiplexed continuous light comprises a component of the first continuous light and a component of the second continuous light; and then one of the branch routing modulators multiplexes the first channel The first continuous light and the second continuous light in the continuous light modulate the same data signal to generate a loaded optical signal; the other branch routing wavelength dependent phase shifter selects one continuous light in the second multiplexed continuous light according to the wavelength Shifting π/2, then using the phase-shifted one continuous light and the other unphase-shifted continuous light output in the second multiplexed continuous light as the phase-shifted optical signal; finally, the optical coupler will load the optical signal and The phase-shifted optical signal is coupled to generate an outgoing optical signal, wherein the outgoing optical signal includes a first outgoing optical signal and a second outgoing optical signal having different wavelengths, and the first outgoing optical signal and the second outgoing optical signal carry the data signal Same but the phase difference is π/2. Such a first outgoing optical signal is converted by the optical signal receiver into a first outgoing electrical signal R _I , and the second outgoing optical signal is converted by the optical signal transmitter into a second outgoing electrical signal R _Q , which is detected by the optical signal receiver by coherent detection In the technique, the formula R _I +j*R _{Q of the} complex signal is recovered, and then the digital signal processing of R _I +j*R _Q can be restored to obtain the data signal modulated in the outgoing optical signal. Since the first outgoing optical signal and the second outgoing optical signal retain the phase signal of the data signal, the coherent detection technique is well utilized to recover the original data signal, and thus is not limited by dispersion, and can be applied to the far as the coherent detection system. The distance transmission solves the problem that the transmission distance in the direct detection system is affected by the dispersion. In addition, since the optical signal transmitter and the optical signal receiver provided by the present invention constitute a direct detection system, the cost is low.

时，经过该波长相关相移器1013后，得到相移光信号的电磁场表示形式为

Optionally, as shown in FIG. 3, the wavelength-dependent phase shifter 1013 may be a straight waveguide, and the length of the straight waveguide satisfies: the frequency difference between the first continuous light and the second continuous light is traveling in the straight waveguide. The phase difference is π/2 when propagating. Illustratively, when the electromagnetic characterization of the second multiplexed continuous light is

When the wavelength dependent phase shifter 1013 is passed, the electromagnetic field representation of the phase shifted optical signal is

Optionally, referring to FIG. 4, the wavelength dependent phase shifter 1013 may include:

The first wavelength division multiplexer 10131 is configured to decompose the second multiplexed continuous light into a first optical path signal and a second optical path signal.

The sub-phase shifter 10132 is configured to phase-shift the second optical path signal output by the first wavelength division multiplexer so that the phase of the first optical path signal and the second optical path signal are different by π/2.

The second wavelength division multiplexer 10133 is configured to multiplex the first optical path signal output by the first wavelength division multiplexer and the phase shifted second optical path signal output by the sub-phase shifter to generate a phase-shift optical signal.

时，经过第一波分复用器10131后，分解为第一光路信号和第二光路信号，假设第一光路信号的电磁场表示形式为

第二光路信号的电磁场表示形式为

子相移器10132对第二光路信号进行相移后得到

然后通过第二波分复用器10133对第一光路信号和经相移的第二光路信号进行耦合得到相移光信号的电磁场表示 形式为

本领域的技术人员可以想到，第一光路信号和第二光路信号是等价的可以互换，本发明在此不再赘述。Illustratively, when the electromagnetic characterization of the second multiplexed continuous light is

When passing through the first wavelength division multiplexer 10131, it is decomposed into a first optical path signal and a second optical path signal, assuming that the electromagnetic field representation of the first optical path signal is

The electromagnetic field representation of the second optical path signal is

The sub-phase shifter 10132 performs phase shift on the second optical path signal to obtain

Then, the first optical path signal and the phase-shifted second optical path signal are coupled by the second wavelength division multiplexer 10133 to obtain an electromagnetic field representation of the phase-shifted optical signal.

It is to be understood by those skilled in the art that the first optical path signal and the second optical path signal are equivalent and may be interchanged, and the present invention will not be described herein.

Further, the first wavelength division multiplexer 10131 and the second wavelength division multiplexer 10133 are interlever (Chinese full name: optical cross-wavelength division multiplexer); or, the first wavelength division multiplexer 10131 is Interlever and the second wavelength division multiplexer 10133 is WSS (English name: wavelength selective switch, Chinese full name: wavelength selection switch); or, the first wavelength division multiplexer 10131 is WSS and the second wavelength division multiplexer 10133 is Or, the first wavelength division multiplexer 10131 and the second wavelength division multiplexer 10133 are interlever; or, the first wavelength division multiplexer 10131 and the second wavelength division multiplexer 10133 are WDMC (English full name: wavelength Division multiplexing coupler, full name in Chinese: WDM coupler). When the first wavelength division multiplexer 10131 adopts interlever or WSS, since the second multiplexed continuous light passes through the first wavelength division multiplexer 10131, it is divided into two parity optical path signals regardless of the wavelength of the input optical wave, so when input It is not necessary to adjust the first wavelength division multiplexer 10131 in accordance with the wavelength of the input light wave every time the wavelength of the light wave changes. The first wavelength division multiplexer 10131 or the second wavelength division multiplexer 10132 uses WDMC, which is simple to manufacture and has a small theoretical insertion loss.

Optionally, as shown in FIG. 5, the wavelength-dependent phase shifter 1013 may be an all-pass type micro-ring structure, and the all-pass type micro-ring structure includes:

MRR (English name: micro ring resonator, Chinese full name: microring resonator) 10134, for passing one of the second multiplexed continuous light through continuous light to generate π/2 phase shift of the resonant continuous light .

The straight waveguide 10135 is for passing the resonant continuous light output by the MRR 10134 and the other non-resonant continuous light of the second multiplexed continuous light.

时，其中的谐振连续光

经过MRR10134后变为

输出后 与另一路连续光

通过直波导10135，最终输出为

本领域的技术人员可以想到，也可以将另一路作为谐振连续光，本发明在此不再赘述。Illustratively, when the electromagnetic characterization of the second multiplexed continuous light is

Resonant continuous light

After MRR10134

After output and another continuous light

Through the straight waveguide 10135, the final output is

It will be appreciated by those skilled in the art that another path may be used as the resonant continuous light, and the present invention will not be described herein.

The present invention provides an optical signal receiver, as shown in FIG. 6, comprising: a wave decomposition multiplexer 1041, a first photodetector 1042, and a second photodetector 1043. among them:

The wave decomposition multiplexer 1041 is configured to receive the outgoing optical signal and decompose the first outgoing optical signal and the second outgoing optical signal, the wavelength of the optical carrier of the first outgoing optical signal and the wavelength of the optical carrier of the second outgoing optical signal Differently, the data signal carried by the first outgoing optical signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2.

As shown in FIG. 6, the wavelength of the optical carrier of the first outgoing optical signal is λ ₁ , and the wavelength of the optical carrier of the second outgoing optical signal is λ ₂ , where λ ₁ ≠λ ₂ . The wave decomposition multiplexer 1041 can also be implemented using an interlever to ensure that it is independent of the wavelength of the outgoing optical signal emitted by the optical signal transmitter.

The first photodetector 1042 is configured to convert the first outgoing optical signal into a first outgoing electrical signal R _I .

The second photodetector 1043 is configured to convert the second outgoing optical signal into a second outgoing electrical signal R _Q .

Similar to the conventional coherent detection principle, the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q are} used by the optical signal receiver 104 to recover the complex signal formula R _I +j*R _Q in the coherent detection technique, and then The digital signal processing of R _I +j*R _{Q is} performed to restore the data signal modulated in the outgoing optical signal.

The optical signal receiver provided by the invention comprises a wave decomposition multiplexer, a first photodetector and a second photodetector. After receiving the optical signal sent by the optical signal transmitter, the optical signal receiver decomposes it into a first outgoing optical signal and a second outgoing optical signal by a wave decomposition multiplexer; then the first photodetector will be the first The outgoing optical signal is converted into a first outgoing electrical signal R _I , and the second outgoing optical signal is converted by the second photodetector into a second outgoing electrical signal R _Q . The optical signal receiver passes the formula R _I +j*R _Q of the recovered complex signal in the coherent detection technique, and then digitally processes the R _I +j*R _Q to obtain the data signal modulated in the outgoing optical signal. . Since the first outgoing optical signal and the second outgoing optical signal retain the phase signal of the data signal, the coherent detection technique is well utilized to recover the original data signal, and thus is not limited by dispersion, and can be applied to the far as the coherent detection system. The distance transmission solves the problem that the transmission distance in the direct detection system is affected by the dispersion. In addition, since the optical signal transmitter and the optical signal receiver provided by the present invention constitute a direct detection system, the cost is low.

In addition, the optical signal transmitter and the optical signal receiver provided by the present invention have the following advantages:

Since there is no loss of phase signal, the dispersion, PMD (English full name: polarization mode dispersion, Chinese full name: polarization mode dispersion) are not limited, and can be used in the DSP for dispersion and PMD compensation, complete restoration of the originating signal.

Low requirements for laser linewidth and wavelength accuracy. There are great advantages in scenarios where the wavelength resources are abundant and the cost requirements are severe. Very suitable for metropolitan area network architecture. The cost of device integration is lower.

Since the optical signal transmitter does not use polarization multiplexing as in the conventional coherent detection system, the optical signal receiver does not need to be depolarized, nor has polarization tracking, and avoids ICR (English full name: integrated coherent receivers, Chinese full name: integrated coherent reception) Machines and other complex devices and complex algorithms in the DSP, so the optical signal receiver is extremely low cost.

Although the optical signal transmitter uses two wavelengths, it shares a single modulator and loads the same electrical signal. The cost is very low after integration. Equivalent to the optical signal transmitter to send the local oscillator signal, so no SOP (English full name: state of polarization, Chinese full name: polarization state) tracking and LOFO (English full name: local oscillator frequency offset, Chinese full name: local oscillator frequency offset) compensation .

The two wavelengths of the optical signal transmitter can be spaced at 25 GHz, and the spectral efficiency is equivalent to a 50 GHz spaced wavelength division multiplexing system. Or the two wavelengths of the optical signal transmitter may be at 50 GHz intervals, and the spectral efficiency is equivalent to a 100 GHz spaced wavelength division multiplexing system.

The theoretical insertion loss is small, and the multi-stage optical coupler using the foregoing scheme is avoided.

Can be used in a variety of modulation formats, such as ASK (English full name: amplitude shift keying, Chinese full name: amplitude shift keying), PSK (English full name: phase shift keying, Chinese full name: phase shift keying), QAM (English full name :quadrature amplitude modulation, Chinese full name: quadrature amplitude modulation), OFDM (English full name: orthogonal frequency division multiplexing, Chinese full name: orthogonal frequency division multiplexing) / DMT (English full name: discrete multi-tone, Chinese full name: discrete multiple Modulation format such as pitch).

The present invention provides an optical signal transmission method for use in an optical signal transmitter as described above, as shown in FIG. 7, the method comprising:

S101. Coupling the first continuous light and the second continuous light to generate first multiplexed continuous light and second multiplexed continuous light, wherein a wavelength of the first continuous light is different from a wavelength of the second continuous light, The one-way multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light.

S102. Modulate the same data signal on the component of the first continuous light and the component of the second continuous light in the first multiplexed continuous light to generate a load optical signal.

S103. Select one channel continuous light of the second multiplexed continuous light according to the wavelength to phase shift by π/2, and multiplex the phase-shifted one continuous light and the other unphase-shifted continuous light in the second multiplexed continuous light. The light output acts as a phase shifted optical signal.

S104. Coupling the loaded optical signal and the phase-shifted optical signal to generate an outgoing optical signal, where the outgoing optical signal includes a first outgoing optical signal and a second outgoing optical signal, and a wavelength of the optical carrier of the first outgoing optical signal is second. The wavelength of the optical carrier that emits the optical signal is different, and the data signal carried by the first outgoing optical signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2, and the first outgoing optical signal is used for conversion by the optical signal receiver. For the first outgoing radio signal R _I , the second outgoing optical signal is used for conversion from the optical signal receiver to the second outgoing electrical signal R _Q , and the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q are} used to pass R _I +j*R _Q performs digital signal processing on the DSP and then restores the data signal modulated in the outgoing optical signal.

The optical signal transmission method in the embodiment of the present invention can be applied to the above-mentioned optical signal transmitter. Therefore, the technical effects of the present invention can be referred to the optical signal transmitter.

Optionally, the electromagnetic field representation form of the first continuous light is E ₁ , and the electromagnetic field representation form of the second continuous light is E ₂ ,

第二路复用连续光的电磁场表示形式为

Then the electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

or,

第二路复用连续光的电磁场表示形式为

The electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

为第一连续光的分量，

为第二连续光的分量。among them,

Is the component of the first continuous light,

It is the component of the second continuous light.

The present invention provides another optical signal transmission method for use in an optical signal receiver as described above. Referring to FIG. 8, the method includes:

S201. Receive an outgoing optical signal and decompose the first outgoing optical signal and the second outgoing optical signal therefrom. The wavelength of the optical carrier of the first outgoing optical signal is different from the wavelength of the optical carrier of the second outgoing optical signal, and the first outgoing optical signal The data signal carried by the data signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2.

S202. Convert the first outgoing optical signal into a first outgoing electrical signal R _I .

S203. Convert the second outgoing optical signal into a second outgoing electrical signal R _Q , where the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q are} used for digital signal processing on R _I +j*R _Q The DSP then restores the data signal modulated in the outgoing optical signal.

The optical signal transmission method in the embodiment of the present invention can be applied to the above optical signal. The receiver, and therefore, the technical effects that can be obtained can also be referred to the above-mentioned optical signal receiver, which will not be repeated herein.

It should be understood that, in various embodiments of the present invention, the size of the sequence numbers of the above processes does not mean the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not be taken to the embodiments of the present invention. The implementation process constitutes any limitation.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods for implementing the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

A person skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the system, the device and the unit described above can refer to the corresponding process in the foregoing method embodiment, and details are not described herein again.

In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner, for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be electrical, mechanical or otherwise.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or may be two or two. The upper unit is integrated in one unit.

The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims (12)

An optical signal transmitter, comprising: An optical splitter for coupling the first continuous light and the second continuous light to generate first multiplexed continuous light and second multiplexed continuous light, wherein a wavelength of the first continuous light is The wavelength of the second continuous light is different, the first multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes the first a component of continuous light and a component of the second continuous light; a modulator, configured to modulate a component of the first continuous light and a component of the second continuous light in the first multiplexed continuous light generated by the optical splitter to generate a loaded optical signal; a wavelength-dependent phase shifter for phase-shifting π/2 of one of the second multiplexed continuous lights generated by the optical splitter according to a wavelength, and multiplexing the second multiplexed light One phase of continuous light in phase shift and another continuous light output that is not phase shifted as a phase shifted optical signal; An optical coupler for coupling the loaded optical signal generated by the modulator and the phase shifted optical signal generated by the wavelength dependent phase shifter to generate an outgoing optical signal, wherein the outgoing optical signal includes a first outgoing optical signal and a second outgoing optical signal, wherein a wavelength of an optical carrier of the first outgoing optical signal is different from a wavelength of an optical carrier of the second outgoing optical signal, and data carried by the first outgoing optical signal The signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2, and the first outgoing optical signal is used for being converted by the optical signal receiver into a first outgoing electrical signal R _I , the second outgoing light The signal is used for conversion by the optical signal receiver to a second outgoing electrical signal R _Q , the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q being} used to digitize R _I +j*R _Q The signal processing DSP is then restored to obtain the data signal modulated in the outgoing optical signal. The optical signal transmitter according to claim 1, wherein said wavelength-dependent phase shifter is a straight waveguide, wherein a length of said one straight waveguide satisfies: said first continuous light and said second The frequency difference of the continuous light forms a phase difference of π/2 when the traveling wave propagates in the straight waveguide. The optical signal transmitter of claim 1 wherein said wave Long correlation phase shifters include: a first wavelength division multiplexer, configured to decompose the second multiplexed continuous light into a first optical path signal and a second optical path signal; a phase shifter for phase shifting a second optical path signal output by the first wavelength division multiplexer such that a phase of the first optical path signal and the second optical path signal are different by π/2; a second wavelength division multiplexer for multiplexing the first optical path signal output by the first wavelength division multiplexer and the phase shifted second optical path signal output by the sub-phase shifter to generate The phase shifted optical signal. The optical signal transmitter of claim 3 wherein: The first wavelength division multiplexer and the second wavelength division multiplexer are optical cross-wavelength division multiplexers interlever; or, The first wavelength division multiplexer is interlever and the second wavelength division multiplexer is a wavelength selection switch WSS; or, The first wavelength division multiplexer is WSS and the second wavelength division multiplexer is interlever; or, The first wavelength division multiplexer and the second wavelength division multiplexer are WSS; or, The first wavelength division multiplexer and the second wavelength division multiplexer are wavelength division multiplexing couplers WDMC. The optical signal transmitter according to claim 1, wherein the wavelength-dependent phase shifter is an all-pass type micro-ring structure, and the all-pass type micro-ring structure comprises: a microring resonator MRR for causing one of the second multiplexed continuous lights to pass through the resonant continuous light to generate a π/2 phase shift; a straight waveguide for passing resonant continuous light of the MRR output and another non-resonant continuous light of the second multiplexed continuous light. The optical signal transmitter of claim 1 wherein said tone The controller is biased at the carrier suppression point. The optical signal transmitter of claim 1 wherein: The electromagnetic field of the first continuous light is represented by E ₁ , and the electromagnetic field of the second continuous light is represented by E ₂ . The electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

or, The electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

among them,

For the component of the first continuous light,

Is the component of the second continuous light. An optical signal receiver, comprising: a wave decomposition multiplexer for receiving an outgoing optical signal and decomposing therefrom a first outgoing optical signal and a second outgoing optical signal, a wavelength of an optical carrier of the first outgoing optical signal and a light of the second outgoing optical signal The wavelength of the carrier wave is different, and the data signal carried by the first outgoing optical signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2; a first photodetector for converting the first outgoing optical signal into a first outgoing electrical signal R _I ; A second photodetector for converting the second outgoing optical signal into a second electrical signal R _Q emission, wherein said first exit of said second electrical signal R _I and R _Q for the radio signals by The digital signal processing DSP of R _I +j*R _Q is restored to obtain the data signal modulated in the outgoing optical signal. An optical signal transmission method, comprising: Coupling the first continuous light and the second continuous light to generate first multiplexed continuous light and second multiplexed continuous light, wherein a wavelength of the first continuous light is different from a wavelength of the second continuous light The first multiplexed continuous light includes a component of the first continuous light and a component of the second continuous light, and the second multiplexed continuous light includes a component and a portion of the first continuous light Describe the component of the second continuous light; And modulating the same data signal by the component of the first continuous light and the component of the second continuous light in the first multiplexed continuous light to generate a loaded optical signal; Selecting one of the second multiplexed continuous lights to phase shift by π/2 according to the wavelength, and phasing one phase of the continuous light in the second multiplexed continuous light and the other without phase shifting Continuous light output as a phase shifted optical signal; Combining the loaded optical signal and the phase shifted optical signal to generate an outgoing optical signal, wherein the outgoing optical signal includes a first outgoing optical signal and a second outgoing optical signal, the first outgoing optical signal light The wavelength of the carrier wave is different from the wavelength of the optical carrier of the second outgoing optical signal, and the data signal carried by the first outgoing optical signal is different from the phase of the data signal carried by the second outgoing optical signal by π/2. The first outgoing optical signal is used for conversion by the optical signal receiver into a first outgoing electrical signal R _I , and the second outgoing optical signal is used for conversion from the optical signal receiver to a second outgoing electrical signal R _Q , An outgoing radio signal R _I and the second outgoing electrical signal R _{Q are} used to obtain the data signal modulated in the outgoing optical signal by performing digital signal processing on R _I +j*R _Q . The method of claim 9 wherein: The electromagnetic field of the first continuous light is represented by E ₁ , and the electromagnetic field of the second continuous light is represented by E ₂ . The electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

or, The electromagnetic field representation of the first multiplexed continuous light is

The electromagnetic field representation of the second multiplexed continuous light is

among them,

For the component of the first continuous light,

Is the component of the second continuous light. An optical signal transmission method, comprising: Receiving an outgoing optical signal and decomposing therefrom a first outgoing optical signal and a second outgoing optical signal, the wavelength of the optical carrier of the first outgoing optical signal being different from the wavelength of the optical carrier of the second outgoing optical signal, The data signal carried by an outgoing optical signal is phase-shifted by π/2 from the data signal carried by the second outgoing optical signal; Converting the first outgoing optical signal into a first outgoing electrical signal R _I ; Converting the second outgoing optical signal into a second outgoing electrical signal R _Q , wherein the first outgoing electrical signal R _I and the second outgoing electrical signal R _{Q are} used to pass R _I +j*R _Q After the digital signal processing DSP is performed, the data signal modulated in the outgoing optical signal is obtained. A direct detection system comprising the optical signal transmitter of any of claims 1-7 and the optical signal receiver of claim 8.

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