JP2000224114A - Optical amplifier for amplifying multiple wavelengths - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical amplifier for amplifying multiple wavelengths that monitors an input output signal light for each wavelength. SOLUTION: An optical branch section 20 branches an input light to an optical amplifier section 30 to extract an optical signal with a wavelength, in response to temperature and light receiving units 25-1-25-n receive lights of each wavelength. An input level monitor circuit 26 generates a signal reflecting a power level of the input light to the optical amplifier section 30 from the signal received from the light receiving units and an A/D converter circuit 27 applies A/D conversion to the signal. Similarly, a signal reflecting a power level of an output light of the optical amplifier section 30 is obtained by a circuit block, consisting of an optical branching section 40 to an A/D conversion circuit 47. Temperature control circuits 24, 44 change each element temperature of arrayed waveguide gratings(AWG) 21, 41 to control the wavelength of a transmission light of each AWG to acquire the power levels of a signal component and a noise component. A processing circuit 60 calculates the gain and noise figure of the optical amplifier section 30 from each acquired power level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-wavelength amplification optical amplifier for relaying multi-wavelength optical signals transmitted on an optical transmission line.

[0002]

2. Description of the Related Art Generally, in an optical communication system, a plurality of signal lights having different wavelengths are multiplexed in order to increase a transmission capacity per one optical fiber transmission line (hereinafter simply referred to as [optical transmission line]). In this case, a method of transmitting the light as wavelength multiplexed light is used. Further, in such an optical communication system, a multi-wavelength amplification optical amplifier for amplifying the wavelength multiplexed light as it is is used in order to compensate for the loss of the wavelength multiplexed light on the optical transmission line and extend the transmission distance. It is inserted in the middle of the transmission path. When the multi-wavelength amplification optical amplifier is inserted into the optical transmission line in this way, the operation state of each multi-wavelength amplification optical amplifier must be controlled in order to manage the transmission characteristics of the entire optical transmission line including the multi-wavelength amplification optical amplifier. It is desirable to monitor as closely as possible.

[0003]

By the way, in monitoring the operation state of the multi-wavelength amplification optical amplifier, a gain indicating the operation state of the multi-wavelength amplification optical amplifier itself and a noise indicating the transmission quality of the optical transmission line are used. The index is an important monitor item, and characteristics relating to these items can be obtained by monitoring the input / output signal light of the multi-wavelength amplification optical amplifier. However, the conventional multi-wavelength amplification amplifier merely amplifies the wavelength multiplexed light as it is, and cannot monitor the input / output signal light for each wavelength.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-wavelength amplification amplifier that can monitor input / output signal light for each wavelength.

[0005]

In order to solve the above-mentioned problems, the present invention has the following arrangement. That is, the present invention relates to a multi-wavelength amplification optical amplifier for relaying a multi-wavelength optical signal that is multiplexed and transmitted on an optical transmission line. Input light monitoring means (for example, an optical branching unit 20, an AWG 21, and a light receiver 25-1 to be described later) for extracting a first electric signal reflecting the power level of the input light from the light signal.
25-n, corresponding to the input level monitor circuit 26 and the A / D conversion circuit 27), and a part of the output light is branched to extract an optical signal having a wavelength corresponding to the temperature, and the output light is extracted from the optical signal. Output light monitoring means (for example, an optical branching unit 40, AWG described later) for generating a second electric signal reflecting the power level of
41, the photodetectors 45-1 to 45-n, the output level monitor circuit 46, and the A / D conversion circuit 47) and the characteristics of the multi-wavelength amplification optical amplifier based on the first and second electric signals. Exponent calculation means (e.g., equivalent to a processing circuit 60 described later) for calculating an exponent for performing the operation, and temperature setting means (e.g., temperature detection described later) for setting respective temperatures to the input light monitoring means and the output light monitoring means. Element 2
2, 42, electronic coolers 23, 43, temperature control circuit 24,
44, corresponding to some functions of the processing circuit 60).

Further, the input light monitoring means includes, for example,
A branching unit (for example, corresponding to an optical branching unit 20 described later) for branching a part of the input light, and an extracting unit (for example, described later) for extracting an optical signal having a wavelength corresponding to a temperature from the optical signal branched by the branching unit. AWG 21), and light receiving means (e.g., corresponding to light receiving units 25-1 to 25-n described later) which receive the optical signal extracted by the extracting means and obtain an electric signal corresponding to the amount of received light. A / D conversion means (for example, an A / D conversion circuit 2 described later) for A / D converting the electric signal obtained by the light receiving means to obtain the first electric signal.
7)).

The output light monitoring means may be, for example,
A branching unit (for example, corresponding to an optical branching unit 40 described later) for branching a part of the output light, and an extracting unit (for example, described later) for extracting an optical signal having a wavelength according to a temperature from the optical signal branched by the branching unit. AWG 41) and light receiving means (e.g., corresponding to light receiving units 45-1 to 45-n described later) which receive the optical signal extracted by the extracting means and obtain an electric signal corresponding to the amount of received light. A / D conversion means for A / D converting the electric signal obtained by the light receiving means to obtain the second electric signal (for example, A / D conversion circuit 4 described later)
7)).

[0008] Further, the extraction means may be, for example, an arrayed waveguide grating that changes a transmission wavelength according to the element temperature.
g).

Further, the arrayed waveguide
The grating alternately extracts signal light and noise light from the optical signal branched by the branching unit under element temperature control by the temperature setting unit.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an optical amplifier for multi-wavelength amplification according to an embodiment of the present invention. In the optical amplifier for multi-wavelength amplification shown in the figure, an optical amplifier 30 having an optical amplifying function has an optical transmission line 10 through connectors 10 and 50.
It is interposed between 0A (input side) and 100B (output side) to form a series of transmission paths.

An optical branching unit 20 is provided between the connector 10 and the optical input unit of the optical amplifying unit 30 for branching a part of the input light transmitted through the optical transmission line 100A on the input side. An optical branching unit 40 for branching a part of the output light of the optical amplification unit 30 is provided between the optical output unit of the amplification unit 30 and the connector 50.
Is provided. That is, a part of the input light and a part of the output light of the optical amplifying unit 30 are respectively branched by the optical branching units 20 and 40 and extracted from the transmission path. The optical amplification unit 30 is configured by an optical fiber amplifier using a rare earth-doped fiber such as an Er-doped optical fiber as an amplification medium.

In the branch path of the optical branching section 20, an arrayed waveguide grating that changes the transmission wavelength according to the element temperature is provided.
(Hereinafter referred to as “AWG”) 21 and the AW
The G21 has n output ports for outputting n (n is a natural number) optical signals having different wavelengths.

The AWG 21 includes the AWG 2
1 is mounted with a temperature detecting element 22 such as a thermistor for detecting the element temperature and an electronic cooler 23 such as a Peltier cooler for cooling the AWG 21. The temperature detecting element 22 and the electronic cooler 23 It is connected to the control circuit 24. That is, the temperature control circuit 24
The element temperature of the WG 21 is configured to be arbitrarily set.

The n output ports of the AWG 21 are connected to light receivers 25-1 to 25-n for receiving the output light (transmitted light) of the AWG 21, respectively. The signal is input to the input level monitor circuit 26. This input level monitor circuit 26
From the output signals of 5-1 to 25-n, a signal (first electric signal) representing the power level (input level) of the input light of the optical amplifier 30 is output.

On the other hand, elements corresponding to the respective elements provided on the optical input section side of the optical amplifier section 30 are also provided on the optical output section side of the optical amplifier section 30. That is, the optical amplifier 30
An AWG 41 that changes a transmission wavelength according to the element temperature is provided in a branch path of the optical branching unit 40 provided between the optical input unit and the connector 50.
Like the AWG 21, it has n output ports for outputting n (n is a natural number) optical signals having different wavelengths.

The AWG 41 has a temperature detecting element 42 such as a thermistor and an electronic cooler 43 such as a Peltier cooler. The temperature detecting element 42 and the electronic cooler 43 are connected to a temperature control circuit 44. You. That is, the element temperature of the AWG 41 can be arbitrarily set by the temperature control circuit 44.

A light receiving device 4 for receiving the output light of the AWG 41 is connected to n output ports of the AWG 41.
5-1 to 45-n are respectively connected, and respective output signals of these photodetectors are input to an output level monitor circuit 46.
The output level monitor circuit 46 includes the photodetectors 45-1 to 45-4.
A signal (second electrical signal) representing the power level (output level) of the output light of the optical amplifier 30 is output from the 5-n output signal.

The respective signals output from the A / D conversion circuits 27 and 47 are input to a processing circuit 60 and subjected to predetermined arithmetic processing to calculate various indices indicating the operation state of the optical amplifier 30. Is done. Further, the processing circuit 60 gives an instruction necessary for executing the processing to the temperature control circuits 24 and 44.

Next, the operation of the multi-wavelength amplification optical amplifier according to this embodiment will be described for the case where the gain of the amplifier and various noise factors are monitored. The optical amplifier for multi-wavelength amplification monitors the power levels of the input light and the output light of the optical amplifier 30 and calculates the gain and noise figure of the optical amplifier 30. Is controlled, so that a power level for each wavelength can be obtained.

Hereinafter, the operation will be described in detail. AWG21
When wavelength-multiplexed light (branched light) is input from the optical branching unit 20, the light is decomposed for each wavelength component and output to n output ports. The light receivers 25-1 to 25-n are AWG
The optical signal of each wavelength component output from each output port 21 is received. As a result, the power level for each wavelength of the wavelength multiplexed light is output from the input level monitor circuit 26,
The power level converted into digital data is output from the D conversion circuit 27.

Here, the AWG2 is controlled by the temperature control circuit 24.
When the element temperature is changed, the wavelength of the light output from the output port (the transmitted light of the AWG) shifts substantially in proportion to the temperature difference. For example, when the wavelength of the light output from each output port of the AWG 21 at a certain temperature T0 is λ1... Λn, when the temperature changes to T0 + ΔT, the wavelength of the output light of the AWG21 becomes λ1 + Δλ,. . . . . , Λn + Δλ.

Therefore, the wavelength λ 1. . . .lambda.n is set in the optical transmission lines 100A and 100A.
If the temperature of the AWG 21 is set so as to coincide with the wavelength of each signal component of the wavelength-division multiplexed light transmitted through B, the optical amplifier 30
The power levels Psi1 to Psin for each wavelength of the signal component of the wavelength multiplexed light input to the AWG 21 are obtained from each output port of the AWG 21. Also, the wavelength of the light output from the AWG 21 is
When the temperature of the AWG 21 is set so as to be the light wavelength close to the signal light wavelength, the light output from the AWG 21 becomes noise light at a wavelength close to the signal light, and is included in the wavelength multiplexed light input to the optical amplifier 30. Power levels Pni1 to Pnin for each wavelength of the noise component to be obtained.

On the other hand, on the optical output side of the optical amplifying unit 30, the power level of the output light is similarly monitored for each wavelength. That is, when the wavelength-multiplexed branch light is input from the optical branching unit 40, the AWG 41 decomposes the split light for each wavelength component and outputs it to n output ports. The output light from each output port is received by each of the light receivers 45-1 to 45-n. As a result, the A / D conversion circuit 47 outputs the power level for each wavelength of the wavelength multiplexed light output from the optical amplifier 30. Is output. Here, by controlling the element temperature of the AWG 41, the wavelength of the light passing through the AWG 41 is shifted, so that the power levels Pso1 to Pson of the wavelength of the signal component of the wavelength multiplexed light output from the optical amplifying unit 30 for each wavelength and noise Power levels Pno1 to Pnon for each component wavelength are obtained.

The processing circuit 60 includes A / D conversion circuits 27 and 4
Based on the output signal from 7, various indices indicating the operation state of the optical amplifier 30 are calculated. For example, the optical amplifier 30
By calculating the ratio between the power levels Psi1 to Psin of the signal components of the input light and the power levels Pso1 to Pson of the output light, the gain for each wavelength in the optical amplifier 30 is calculated. Also, the power levels Psi1 to Psin and the power levels Pni1 to
By taking the ratio with Pnin, the input light SN ratio (SNi1 ~
SNin). Also, the power levels Pso1 to Pson
Then, the output light SN ratio (SNo1 to SNon) is calculated by taking the ratio between the power levels Pno1 to Pnon. Further, power levels SNi1 to SNin and power levels SNo1 to SN
The noise figure for each wavelength of the optical amplification unit 30 is calculated by taking the ratio with on. As described above, the gain of the optical amplifier 30 and various noise factors are calculated.

As described above, according to this embodiment, it is possible to monitor the gain and noise figure of the multi-wavelength amplification optical amplifier for each signal light wavelength of the multi-wavelength signal.
Further, it becomes possible to monitor the signal light and the noise light alternately by changing the transmission wavelength by changing the element temperature of an AWG (Arrayed Waveguide Grating).

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and the present invention is applicable to any design change or the like without departing from the gist of the present invention. included. For example, in the above-described embodiment, the wavelengths output from the respective output ports are simultaneously shifted by changing the temperatures of the AWGs 21 and 41. However, the AWGs are independently provided for each wavelength, and the temperature of each AWG is changed. May be set independently. This allows
It is possible to simultaneously acquire the power levels of the signal component and the noise component.

[0027]

As described above, according to the present invention, a part of the input light and the output light is branched to extract an optical signal having a wavelength corresponding to the temperature, and the input light and the output light are extracted from the optical signal. An index for evaluating the characteristics of a multi-wavelength amplification optical amplifier by acquiring the optical power level is calculated, realizing a multi-wavelength amplification optical amplifier that can monitor input and output signal light for each wavelength. Therefore, the gain of the optical amplifier for directly amplifying the wavelength multiplexed light and the SN of the input / output
The ratio or noise figure can be monitored for each signal light wavelength.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical amplifier for multi-wavelength amplification according to an embodiment of the present invention.

[Explanation of symbols]

10, 50 ... connector, 20, 40 ... optical branching part, 21,
41 ... Arrayed waveguide grating (A
WG: Arrayed Waveguide Grating, 22, 42 temperature detecting element, 23, 43 electronic cooler, 24, 44 temperature control circuit, 25-1 to 25-n, 45-1 to 45-n
... receiver, 26 ... input level monitor circuit, 27, 47 ...
A / D conversion circuit, 46 ... output level monitor circuit, 60 ...
Processing circuit, 100A, 100B ... optical transmission path.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04J 14/02

Claims (5)

[Claims] An optical amplifier for multi-wavelength amplification for relaying a multi-wavelength optical signal multiplexed and transmitted on an optical transmission line, wherein a part of the input light is branched to a wavelength corresponding to a temperature. An input light monitoring means for extracting an optical signal and generating a first electric signal reflecting the power level of the input light from the optical signal; a light having a wavelength corresponding to the temperature by branching a part of the output light; Output light monitoring means for extracting a signal and generating a second electric signal reflecting the power level of the output light from the optical signal; and an optical amplifier for multi-wavelength amplification based on the first and second electric signals An index calculating means for calculating an index for evaluating the characteristic of: and a temperature setting means for setting respective temperatures for the input light monitoring means and the output light monitoring means; Optical amplifier for amplification. 2. The input light monitoring means comprises: a branching means for branching a part of the input light; an extracting means for extracting an optical signal having a wavelength according to a temperature from the optical signal branched by the branching means; A light receiving unit that receives the optical signal extracted by the extracting unit and obtains an electric signal corresponding to the amount of the received light; an A / D conversion of the electric signal obtained by the light receiving unit and the first electric signal 2. An optical amplifier for multi-wavelength amplification according to claim 1, comprising: A / D conversion means for obtaining: 3. The output light monitoring unit includes: a branching unit that branches a part of the output light; an extraction unit that extracts an optical signal having a wavelength according to a temperature from the optical signal branched by the branching unit; A light receiving unit that receives the optical signal extracted by the extracting unit and obtains an electric signal corresponding to the amount of the received light; an A / D conversion of the electric signal obtained by the light receiving unit and the second electric signal 2. An optical amplifier for multi-wavelength amplification according to claim 1, comprising: A / D conversion means for obtaining: 4. The apparatus according to claim 2, wherein said extracting means comprises an arrayed waveguide grating which changes a transmission wavelength according to the element temperature. Optical amplifier for multi-wavelength amplification. 5. The arrayed waveguide grating alternately extracts signal light and noise light from the optical signal branched by the branching unit under element temperature control by the temperature setting unit. The optical amplifier for multi-wavelength amplification according to claim 4.