WO2020155249A1 - Dual-frequency light source - Google Patents

Abstract

A dual-frequency light source, comprising a pump unit (10), a first resonant cavity, and a second resonant cavity, the first resonant cavity comprising a gain medium (20), a common reflection filter unit (30), and a first reflection filter unit (40), and the second resonant cavity comprising the gain medium (20), the common reflection filter unit (30), and a second reflection filter unit (60), and further comprising a tuning unit configured to tune a center wavelength and/or bandwidth of the first reflection filter unit (40) and/or to tune a center wavelength and/or bandwidth of the second reflection filter unit (60), so as to obtain tunable first single-frequency laser light and tunable second single-frequency laser light. Extremely narrow linewidth single-frequency laser output is achieved on the basis of bias filtering, tunable dual-frequency laser light is obtained by the tuning unit, and the output laser light is stable and simple to tune; the dual-frequency light source has a large tuning range and has a greater potential to be a detection light source.

Description

A dual-frequency light source

This application is required to be submitted to the Chinese Patent Office on January 31, 2019, the application number is 201910099908.5, the title of the invention is "a dual-frequency light source", and it is submitted to the China Patent Office on January 31, 2019, the application number is 201920179007.2, the name of the invention The priority of the Chinese patent application for "a dual-frequency light source", the entire content of which is incorporated in this application by reference.

Technical field

This application belongs to the field of optical technology, and particularly relates to a dual-frequency light source.

Background technique

The development of laser technology has strongly promoted the development of optical communications, nonlinear optics, high-resolution optics and other fields, especially in the field of precision interferometry. Precision interferometry mainly uses laser wavelength as a "ruler", and uses the principle of interference to measure various parameters, such as acceleration, displacement, angular displacement, and so on. Since the wavelength of light is on the order of nm, its resolution accuracy is unmatched by electrical and magnetic components. The laser interferometer has been widely used in the field of precision and ultra-precision length measurement due to its unique advantages of large measurement range, high resolution and high measurement accuracy. The lasers mainly used in laser interference are single-frequency lasers and dual-frequency lasers. The laser measuring instrument used earlier is a single-frequency interferometer based on a single-frequency laser, but the interferometer is more severely affected by environmental factors, especially when the measurement environment is harsh and the measurement distance is long. The main reason is that it generates a direct current signal. When measuring at a large distance, the attenuation of light energy, the existence of air turbulence, the change of background light intensity and other interference to the laser beam will cause the beam to shift, which inevitably makes the laser beam intensity Changes occur, resulting in a drift of DC light intensity and level. Because the single-frequency interferometer is largely limited by the drift of the DC amplifier, the sensitivity of the optical receiver and the fluctuation of the laser power during measurement, the single-frequency laser interferometer is difficult to use in high-precision measurement.

The dual-frequency laser interferometer developed on the basis of the single-frequency laser interferometer is a heterodyne interferometer. Its most notable feature is the use of carrier technology to convert the measured physical quantity information into a frequency modulation or amplitude modulation signal, which overcomes the common The single-frequency interferometer measures the DC drift of the signal. It has many advantages such as low signal noise, resistance to environmental interference, and allows multi-channel multiplexing of light sources. It is widely used in advanced manufacturing and nanotechnology fields as distance measurement, speed measurement, and vibration measurement. , Shape measurement, real-time position measurement and control, etc.

The dual-frequency lasers currently in use mainly include Zeeman dual-frequency lasers, dual-longitudinal-mode dual-frequency lasers, and the birefringent dual-frequency laser proposed by the research group of Professor Zhang Shulian of Tsinghua University. Zeeman dual-frequency lasers use the Zeeman effect, which refers to a phenomenon in which the spectral lines emitted by the light source will split if the light source is placed in a magnetic field. Zeeman dual-frequency laser output frequency difference is generally below 1MHz, generally not used for high-speed precision laser heterodyne interferometry. Dual longitudinal mode lasers can output lasers with two longitudinal mode frequencies in a laser resonator by controlling the cavity length of the laser. The longitudinal mode frequency difference can reach 600MHz-1GHz (the corresponding laser tube length is 150mm-250mm). The birefringent dual-frequency laser is a single longitudinal mode laser resonator, inserting a birefringent optical element such as quartz crystal, calcite, etc., so that the laser in the cavity is split into o light and e with different optical cavity lengths Light, the output of the two orthogonal linearly polarized dual-frequency laser oscillations, the frequency difference is between 3-40MHz, and the required frequency difference can be obtained by adjusting the stress of the birefringent crystal.

Among the above three dual-frequency lasers, the common feature is that the laser frequency is more difficult to tune, and the frequency difference adjustment range is relatively limited. For example, the frequency difference of Zeeman can only be adjusted in a relatively small range. It can only be adjusted in a relatively large range, while the birefringence can only be adjusted in a certain range in the middle. The effect is not ideal, and the light of two frequencies is orthogonally polarized, and the polarization state needs to be corrected before it can be used for interference. Therefore, it is necessary to develop a dual-frequency light source with a simpler tuning method and a larger tuning range.

technical problem

The purpose of this application is to provide a dual-frequency light source, including but not limited to solving the technical problem of a small tuning range of a traditional dual-frequency light source.

Technical solutions

To solve the above technical problems, the technical solution adopted in this application is: a dual-frequency light source, including

Pump unit for outputting pump light;

The first resonant cavity is used to generate a tunable first single-frequency laser;

The second resonant cavity is used to generate a tunable second single frequency laser;

The first resonant cavity includes:

Gain medium, used to generate excitation light by pump light excitation;

The common reflection filtering unit and the first reflection filtering unit are used to reflect and filter the excitation light, and the filtering ranges of the common reflection filtering unit and the first reflection filtering unit partially overlap to realize narrowband filtering. Obtain the first single-frequency laser;

The second resonant cavity includes:

The gain medium is used to generate excitation light through pump light excitation;

The common reflection filtering unit and the second reflection filtering unit are used to reflect and filter the excitation light, and the filtering ranges of the common reflection filtering unit and the second reflection filtering unit partially overlap to achieve narrowband filtering, Used to obtain the second single frequency laser.

Beneficial effect

The dual-frequency light source provided by the present application has the following beneficial effects: through the common reflection filter unit and the first reflection filter unit, an extremely narrow linewidth single-frequency laser output is realized based on deviation filtering, and the common reflection filter unit and the second reflection filter unit are based on Deviation filtering realizes extremely narrow linewidth single-frequency laser output, and obtains the first single-frequency laser and the second single-frequency laser. Furthermore, dual-frequency output is realized on the basis of obtaining extremely narrow linewidth laser by deviation filtering.

Description of the drawings

In order to more clearly explain the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings needed in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only of the present invention. For some embodiments, for those of ordinary skill in the art, other drawings may be obtained based on these drawings without creative work.

FIG. 1 is a single longitudinal mode operation principle diagram of a first resonant cavity and a second resonant cavity of a dual-frequency light source provided by an embodiment of the present application;

FIG. 2 is a principle diagram of adjusting the center wavelength of the first single-frequency laser of the dual-frequency light source according to an embodiment of the present application;

FIG. 3 is a schematic diagram of bandwidth adjustment of a first single-frequency laser of a dual-frequency light source provided by an embodiment of the present application;

4 is a structural diagram of a dual-frequency light source provided by the first embodiment of the present application;

FIG. 5 is a structural diagram of another dual-frequency light source provided by the first embodiment of the present application;

6 is a structural diagram of a dual-frequency light source provided by a second embodiment of the present application;

Fig. 7 is a structural diagram of a dual-frequency light source provided by a third embodiment of the present application;

FIG. 8 is a structural diagram of a dual-frequency light source provided by the fourth embodiment and the eighth embodiment of the present application;

FIG. 9 is a structural diagram of a dual-frequency light source provided by a fifth embodiment of the present application;

10 is a structural diagram of a dual-frequency light source provided by a sixth embodiment of the present application;

FIG. 11 is a structural diagram of a dual-frequency light source provided by a seventh embodiment of the present application;

FIG. 12 is a structural diagram of a common reflection filtering unit, a first reflection filtering unit, and a second reflection filtering unit of a dual-frequency light source according to an embodiment of the present application;

FIG. 13 is another structural diagram of the common reflection filter unit, the first reflection filter unit, and the second reflection filter unit of the dual-frequency light source provided by an embodiment of the present application.

Embodiments of the invention

In order to make the objectives, technical solutions, and advantages of this application clearer, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the application, and not used to limit the application.

It should be noted that when a component is referred to as being "fixed to" or "installed on" another component, it can be directly or indirectly located on the other component. When a component is said to be "connected" to another component, it can be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. The indicated orientation or position is based on the orientation or position shown in the drawings, which is only for the convenience of description and cannot be understood as a limitation of the technical solution. The terms "first" and "second" are only used for ease of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. The meaning of "plurality" means two or more than two, unless otherwise specifically defined.

In order to illustrate the technical solutions described in this application, detailed descriptions are given below in conjunction with specific drawings and embodiments.

4 and 5, an embodiment of the present application provides a dual-frequency light source, including a pumping unit 10 for outputting pump light; a first resonant cavity for generating a tunable first single-frequency laser; Two resonant cavities, used to generate tunable second single frequency laser. Specifically, the first resonant cavity includes: a gain medium 20 for generating excitation light after being excited by pump light; a common reflection filtering unit 30 and a first reflection filtering unit 40 for reflecting and filtering laser light, and common reflection filtering The filtering ranges of the unit 30 and the first reflection filtering unit 40 partially overlap to achieve ultra-narrowband filtering, thereby obtaining the first single-frequency laser; the second resonant cavity includes: the gain medium 20, which is used to generate laser light after excitation by the pump light; The reflection filtering unit 30 and the second reflection filtering unit 60 are used to reflect and filter the laser light. The filtering ranges of the common reflection filtering unit 30 and the second reflection filtering unit 60 partially overlap to achieve ultra-narrowband filtering, thereby obtaining the second single Frequency laser. In this embodiment, the “reflection” refers to the reflection of light intensity, and the “filtering” refers to the filtering of frequency.

Specifically, in the dual-frequency laser light source, the common reflection filter unit 30 and the first reflection filter unit 40 form two ends of the first resonant cavity, and the common reflection filter unit 30 and the second reflection filter unit 60 form the second resonant cavity. At both ends of, the common reflection filter unit 30 is a common part of the first resonant cavity and the second resonant cavity, and the gain medium 20 is also a common part of the first resonant cavity and the second resonant cavity. In the first resonant cavity, the common reflection filter unit 30 can reflect the light intensity and filter the laser frequency, and the first reflection filter unit 40 can reflect the light intensity and filter the laser frequency. 1, the first reflection filter unit 40 and the common reflection filter unit 30 have filter bandwidths L1 and L0, respectively, and the filter bandwidths L1 and L0 have an overlapping frequency band L10. The overlapping frequency band L10 has a smaller bandwidth and can be based on the The deviation filter obtains the single longitudinal mode resonance, and obtains the first single frequency laser. The second reflection filter unit 60 and the common reflection filter unit 30 have filter bandwidths L2 and L0, respectively. The filter bandwidths L2 and L0 have an overlapping frequency band L20, which has a smaller bandwidth, and thus can obtain single longitudinal mode resonance. Obtain the second single-frequency laser.

The dual-frequency light source provided by the embodiment of the present application uses the common reflection filter unit 30 and the first reflection filter unit 40 to achieve extremely narrow linewidth single-frequency laser output based on deviation filtering, the first single-frequency laser and the second single-frequency laser, and then Based on the deviation filtering to obtain the extremely narrow linewidth laser, the dual-frequency output is realized, and the output laser is stable.

Further, the dual-frequency light source further includes a tuning unit. Specifically, the tuning unit (the first tuning unit 50) is connected to the first reflection filter unit 40 for adjusting the center wavelength and/or bandwidth of the first reflection filter unit 40 , To obtain the tunable first single frequency laser. It may also be that the tuning unit (the second tuning unit 70) is connected to the second reflection filter unit 60 and is used to adjust the center wavelength and/or bandwidth of the second reflection filter unit 60 to obtain a tunable second single frequency laser. It may also be that the tuning unit (the third tuning unit 33) is connected to the common reflection filter unit for obtaining the tunable first single-frequency laser and the tunable second single-frequency laser simultaneously. The tuning unit may alternatively be connected to the first reflection filtering unit 40, the second reflection filtering unit 60, and the common reflection filtering unit 30, or may be connected to two filtering units or to three filtering units at the same time.

Further referring to FIG. 2, the center wavelength λ1 of the first reflection filter unit 40 is adjusted by the first tuning unit 50, while the center wavelength λ0 of the common reflection filter unit 30 is kept unchanged, the center of the first single-frequency laser obtained The wavelength is shifted from λ101 to λ102. 3, the first tuning unit 50 is used to adjust the filter bandwidth L1 of the first reflection filter unit 40, and the third tuning unit 33 is used to adjust the filter bandwidth L0 of the common reflection filter unit 30, the bandwidth of the first single-frequency laser Change from L101 to L102. In other embodiments, adjusting the first tuning unit 50 while keeping the common reflection filter unit 30 unchanged can also obtain the tunable first single-frequency laser. Of course, adjusting the center wavelength λ0 and the filter bandwidth L0 of the common reflection filter unit 30 at the same time can make the adjustment of the center wavelength and bandwidth of the first single-frequency laser more flexible and with a larger adjustable range. Similarly, by adjusting the center wavelength and bandwidth of the second reflection filter unit 60 through the second tuning unit 70, or further adjust the common reflection filter unit 30 at the same time, the center wavelength and bandwidth of the second single-frequency laser can be adjusted.

Furthermore, the dual-frequency light source provided by the embodiment of the present application further has the following effects:

Through the common reflection filter unit 30 and the first reflection filter unit 40, a very narrow linewidth single-frequency laser output is realized based on deviation filtering, and the first reflection filter unit 40 is adjusted by the first tuning unit 50 to obtain a tunable first single frequency laser output. Frequency laser, through the common reflection filter unit 30 and the second reflection filter unit 60, based on deviation filtering to achieve a very narrow linewidth single-frequency laser output, through the second tuning unit 70 to adjust the second reflection filter unit 60 to obtain a tunable The second single-frequency laser realizes dual-frequency output based on the deviation filtering to obtain extremely narrow linewidth laser, and the output laser is stable and easy to tune; and the theoretical frequency difference of the dual-frequency light source is the entire common reflection filter unit The spectrum of 30 can reach more than tens of MHz, with a large tuning range, and has a stronger potential as a detection light source.

The deviation filtering method used in the embodiments of the present application to obtain the first single-frequency laser and the second single-frequency laser has the following effects: Compared with the traditional single-frequency light source using narrow-band fiber grating and broadband fiber grating as the cavity mirror, one On the other hand, there is no need to set up extremely narrow-band fiber gratings that are extremely difficult to manufacture, and the bandwidth requirements of the common reflection filter unit 30, the first reflection filter unit 40, and the second reflection filter unit 60 are not high. The narrow filtering range is limited by the requirements, and it can be composed of gratings with lower parameters, which greatly reduces the process difficulty.

On the other hand, in order to obtain a single-frequency laser from a traditional single-frequency light source, the reflection bandwidth of the narrow-band grating must be smaller than the longitudinal mode interval. The shorter the cavity length, the greater the longitudinal mode interval, and the lower the requirement for narrow-band gratings. However, the cavity length is shorter. The output power will be lost, and the traditional single-frequency light source has the mutual restriction of narrow-band grating performance and output power. However, this embodiment does not completely rely on the filtering performance of either end filter unit, that is, it is not necessary to make any filter bandwidth smaller than the longitudinal mode interval. Therefore, the restriction on the cavity length is lifted, and the filtering performance and output power of each reflection filter unit are prevented from mutually restricting each other, and the selection of each reflection filter unit and the design of the resonant cavity are more flexible.

Based on the above design, the following embodiments 1 to 3 provide several dual-frequency light sources with a straight cavity structure.

Example one:

4, the dual-frequency light source of the straight cavity structure includes the above-mentioned pump unit 10, gain medium 20, common reflection filter unit 30, first reflection filter unit 40, first tuning unit 50, and second reflection filter unit. 60. The second tuning unit 70. Among them, the common reflection filter unit 30, the first reflection filter unit 40 and the second reflection filter unit 60 are arranged in a straight line, the gain medium 20 is arranged between the common reflection filter unit 30 and the first reflection filter unit 40; the common reflection filter unit 30 and the first reflection filter unit 40 constitute both ends of the first resonant cavity, the common reflection filter unit 30 and the second reflection filter unit 60 constitute both ends of the second resonant cavity, the first resonant cavity and the second resonant cavity have a common section , That is, the part between the common reflection filtering unit 30 and the first reflection filtering unit 40. In order to realize the laser transmission in the second resonant cavity, the first reflection filter unit 40 includes a first reflection filter waveband region 41 and a first transmission waveband region 42. A part of the energy of the laser light is totally reflected or high in the first reflection filter waveband region 41. Reflection and filtering are used to form a tunable first single-frequency laser. Another part of the energy of the laser is transmitted from the first transmission band region 42 to the second reflection filter unit 60, and is totally reflected by the second reflection filter unit 60 and then again by The first transmission band region 42 transmits to the common reflection filter unit 30 for forming a tunable second single-frequency laser.

As shown in Fig. 5, as another dual-frequency light source structure, a third tuning unit 33 can be provided, connected to the common reflection filter unit 30, and a tunable first single-frequency laser and a tunable second single-frequency laser can be simultaneously obtained.

In the first embodiment, the common reflection filter unit 30 adopts a partial reflection filter unit, which is used to partially reflect and filter the laser light in the cavity and output the first single frequency laser light and the second single frequency laser light. In addition, a first pump light coupling unit 81 is provided between the pump unit 10 and the common reflection filter unit 30 to couple the pump light from the common reflection filter unit 30 into the first resonant cavity and the second resonant cavity; The common reflection filter unit 30 outputs the first single-frequency laser light and the second single-frequency laser light, which are then output through the first pump light coupling unit 81.

It can be understood that when tuning is not required, the first tuning unit 50, the second tuning unit 70, and the third tuning unit 33 may not be used in this embodiment, and only a dual-frequency laser with a fixed frequency is output.

Further, the isolation unit 90 can also be provided in the direction in which the first pump light coupling unit 81 outputs the first single-frequency laser light and the second single-frequency laser light. It is also possible to provide another isolation unit between the pump unit 10 and the first pump light coupling unit 81 to avoid reflection back to the pump source and burn the pump source.

In the embodiment of the present application, between the pump unit 10 and the first pump light coupling unit 81, between the first pump light coupling unit 81 and the common reflection filter unit 30, the first pump light coupling unit 81 and the isolation The units 90 can all be connected by optical fibers to realize an all-fiber dual-frequency light source.

Alternatively, the pump unit 10 and the first pump light coupling unit 81 may be connected by an optical fiber, and the first pump light coupling unit 81 and the isolation unit 90 may be connected by an optical fiber. The first pump light coupling unit 81 and The common reflection filter unit 30 can transmit light through free space to realize a dual-frequency light source of some optical fibers.

Alternatively, the pump unit 10 and the first pump light coupling unit 81 can transmit light through free space, and the first pump light coupling unit 81 and the common reflection filter unit 30 can transmit light through an optical fiber. The coupling unit 81 and the isolation unit 90 may be connected by an optical fiber, or a dual-frequency light source of partial optical fiber may be realized.

It is also possible to use other free space and optical fiber hybrid connection methods, or adopt a full free space connection method.

Embodiment two:

Referring to FIG. 6, in the straight cavity structure provided by the second embodiment, the common reflection filter unit 30 still adopts a partial reflection filter unit, which is used to partially reflect and filter the laser light in the cavity and output the first single frequency laser and the second single frequency. laser. The difference from the first embodiment is that a second pump light coupling unit 82 is provided in the first resonant cavity or the second resonant cavity to couple the pump light into the first resonant cavity and the second resonant cavity. At this time, the pump light enters through the side of the resonator, and the tunable first single-frequency laser and the second single-frequency laser are output through the common reflection filter unit 30.

As in the first embodiment, all devices can be connected by all-optical fiber, or a combination of free-space connection and fiber-optic connection, or full-space connection, etc.

Example three:

Referring to FIG. 7, in the straight cavity structure provided in the third embodiment, the difference from the first embodiment is that the public reflection filter unit 30 adopts a total reflection filter unit for total reflection and filtering of the laser; in the first resonant cavity or A third pump light coupling unit 83 is provided in the second resonant cavity for inputting pump light through the side end of the first resonant cavity or the second resonant cavity; it is set in the common part of the first resonant cavity and the second resonant cavity The output unit 100 is used to output the first single-frequency laser and the second single-frequency laser.

As in the first embodiment, all devices can be connected by all-optical fiber, or a combination of free-space connection and fiber-optic connection, or full-space connection, etc.

The following provides a dual-frequency light source with a ring cavity structure through the fourth to eighth embodiments.

Embodiment four:

Referring to FIG. 8, in the dual-frequency light source of the ring cavity structure, the first resonant cavity and the second resonant cavity are in the ring cavity structure. The dual-frequency light source includes the above-mentioned pump unit 10, gain medium 20, common reflection filter unit 30, In addition to the first reflection filter unit 40, the first tuning unit 50, the second reflection filter unit 60, and the second tuning unit 70, it also includes a fourth pump light coupling unit 84, a first coupler 110, and a second coupler 120 The fourth pump light coupling unit 84 has three ports, the first end is connected to the pump unit 10, the second end is directly or indirectly connected to the first coupler 110, and the third end is directly or indirectly connected to the common reflection filter unit 30; The reflection filter unit 40 and the second reflection filter unit 60 are connected in parallel between the first coupler 110 and the second coupler 120, that is, one end of the first reflection filter unit 40 and one end of the second reflection filter unit 60 are directly or indirectly connected together. Connected to the first coupler 110, the other end of the first reflection filter unit 40 and the other end of the second reflection filter unit 60 are directly or indirectly connected to the second coupler 120; the common reflection filter unit 30 is connected to the second coupler 120 and Between the third ends of the fourth pump light coupling unit 84, a ring cavity is formed.

In this embodiment, "directly" means that no other elements other than the light guide cable are arranged between the two, and "indirect" means that other elements other than the light guide cable are also arranged between the two.

For example, an output unit 100 is further provided between the third end of the fourth pump light coupling unit 84 and the common reflection filter unit 30. Further, an isolation unit 90 can also be provided in the output direction of the output unit 100.

A gain medium 20 is also provided between the second end of the fourth pump light coupling unit 84 and the first coupler 110. In addition, the gain medium 20 may also be arranged at other positions in the common section of the first resonant cavity and the second resonant cavity.

Other elements may be provided between one end of the first reflection filter unit 40 and one end of the second reflection filter unit 60 and the first coupler 110, the other end of the first reflection filter unit 40 and the other end of the second reflection filter unit 60 Other elements can also be arranged between the second coupler 120 and the second coupler 120, as in the eighth embodiment.

As in the first embodiment, all devices can be connected by all-optical fiber, or a combination of free-space connection and fiber-optic connection, or full-space connection, etc. When the free space connection is adopted, the light path can be deflected by the reflecting mirror to form a ring cavity structure.

In this embodiment, an isolator may be respectively provided on the two parallel branches between the first coupler 110 and the second coupler 120, and the directions of the two isolators are the same or opposite, that is, the two isolator Clockwise transmission is allowed and counterclockwise transmission is blocked; or counterclockwise transmission is allowed and clockwise transmission is blocked; or one isolator allows clockwise transmission and the other isolator allows counterclockwise transmission.

In this embodiment, an isolator may also be provided on the common section between the fourth pump light coupling unit 84 and the first coupler 110; or, on the fourth pump light coupling unit 84 and the second coupler There is an isolator on the common section between 120 to prevent the laser from being transmitted back.

Embodiment five:

Referring to Fig. 9, the fifth embodiment and the fourth embodiment have the same main structure (such as pumping unit 10, gain medium 20, common reflection filtering unit 30, first reflection filtering unit 40, first tuning unit 50, second reflection The filter unit 60, the second tuning unit 70, the fourth pump light coupling unit 84, the first coupler 110 and the second coupler 120 and their connection structure), the difference is that the output unit 100 is arranged in the second coupler 120 And the common reflection filter unit 30. Further, an isolation unit 90 can also be provided in the output direction of the output unit 100.

Embodiment 6:

10, the sixth embodiment and the fourth embodiment have the same main structure (such as the pump unit 10, the gain medium 20, the common reflection filter unit 30, the first reflection filter unit 40, the first tuning unit 50, the second reflection The filter unit 60, the second tuning unit 70, the fourth pump light coupling unit 84, the first coupler 110 and the second coupler 120 and their connection structure), the difference is that the first coupler 110 and the second coupling An output unit 100 is respectively provided on the two parallel branches between the converter 120, that is, an output unit 100 is provided close to the first reflection filter unit 40 for outputting the tunable first single-frequency laser, and is provided close to the second reflection filter unit 60 The other output unit 100 is used to output a tunable second single frequency laser. Further, an isolation unit 90 may be provided in the output path of each output unit 100.

As in the fourth embodiment, all devices can be connected by all-optical fiber, or a combination of free-space connection and fiber-optic connection, or full-space connection, etc. When the free space connection is adopted, the light path can be deflected by the reflecting mirror to form a ring cavity structure.

Embodiment Seven:

11, the seventh embodiment and the fourth embodiment have the same main structure (such as pumping unit 10, gain medium 20, common reflection filtering unit 30, first reflection filtering unit 40, first tuning unit 50, second reflection The filter unit 60, the second tuning unit 70, the fourth pump light coupling unit 84, the first coupler 110 and the second coupler 120 and their connection structure), the difference is that the common reflection filter unit 30 adopts a partial reflection filter unit , It has the function of outputting the first single-frequency laser and the second single-frequency laser and the function of reflection filtering.

Embodiment 8:

Referring to FIG. 8, the dual-frequency light source of the ring cavity structure has the basic mechanism described in the fourth embodiment, such as the pump unit 10, the gain medium 20, the common reflection filter unit 30, the first reflection filter unit 40, and the first tuning unit 50. , The second reflection filter unit 60, the second tuning unit 70, the fourth pump light coupling unit 84, the first coupler 110 and the second coupler 120 and their connection structure, etc., the difference is that they also include a first circulator 131, the second circulator 132 and the third circulator 133, so as to form the reflection light path of the common reflection filter unit 30, the first reflection filter unit 40, and the second reflection filter unit 60; the first end of the first circulator 131 is connected The first coupler 110, the second end of the first circulator 131 is connected to the first reflection filter unit 40, the third end of the first circulator 131 is connected to the second coupler 120; the first end of the second circulator 132 is connected to the first A coupler 110, the second end of the second circulator 132 is connected to the second reflection filter unit 60, the third end of the second circulator 132 is connected to the second coupler 120; the first end of the third circulator 133 is connected to the second In the coupler 120, the second end of the third circulator 133 is connected to the common reflection filter unit 30, and the third end of the third circulator 133 is connected to the fourth pump light coupling unit 84.

In the above embodiments, for the dual-frequency light source with straight cavity or ring cavity structure, the common reflection filter unit 30, the first reflection filter unit 40, and the second reflection filter unit 60 can all adopt two structures. The integrated structure for frequency filtering and light intensity reflection of laser light is shown in Fig. 12; secondly, a combined structure of two independent modules is adopted, as shown in Fig. 13. The first reflection filter unit 40 includes a first mirror 43 and is arranged on the The first filter module 44 in the reflection direction of a mirror 43; the second reflection filter unit 60 includes a second mirror 61 and a second filter module 62 arranged in the reflection direction of the second mirror 61; the common reflection filter unit 30 includes The common mirror 31 and the common filter module 32 arranged in the reflection direction of the common mirror 31.

It can be understood that the above-mentioned common reflection filter unit 30, first reflection filter unit 40, and second reflection filter unit 60 may adopt an integrated structure at the same time, or a combined structure at the same time, or a part of an integrated structure and a part of a combined structure.

In several embodiments of the present application, the gain medium 20 may be a gain fiber or a block-shaped gain crystal.

As a preferred solution of the embodiments of the present application, the Bragg fiber grating can be directly written on the fiber to form a grating cavity mirror, so the compatibility with the doped active fiber is very good, not only the connection loss is very small, but also the complicated optics is avoided. The structure is convenient for the integration and miniaturization of the fiber laser, so that the fiber laser has better stability and reliability, and is especially suitable for workplaces with very harsh environmental conditions. Therefore, in this embodiment, it is preferable to use an integrated grating cavity mirror formed by directly writing Bragg fiber gratings on the optical fiber as the common reflection filter unit 30, the first reflection filter unit 40 and the second reflection filter unit 60, and the structure is compact. , And for a straight cavity, the length of the entire resonant cavity is short, and the light source has a small volume; for a ring cavity, the volume can also be appropriately reduced.

The above are only preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (15)

A dual-frequency light source, characterized in that it comprises Pump unit for outputting pump light; The first resonant cavity is used to generate a tunable first single-frequency laser; The second resonant cavity is used to generate a tunable second single frequency laser; The first resonant cavity includes: Gain medium, used to generate excitation light by pump light excitation; The common reflection filtering unit and the first reflection filtering unit are used to reflect and filter the excitation light, and the filtering ranges of the common reflection filtering unit and the first reflection filtering unit partially overlap to realize narrowband filtering. Obtain the first single-frequency laser; The second resonant cavity includes: The gain medium is used to generate excitation light through pump light excitation; The common reflection filtering unit and the second reflection filtering unit are used to reflect and filter the excitation light, and the filtering ranges of the common reflection filtering unit and the second reflection filtering unit partially overlap to achieve narrowband filtering, Used to obtain the second single frequency laser. The dual-frequency light source according to claim 1, wherein the first resonant cavity and the second resonant cavity have a straight cavity structure, and the common reflection filter unit, the first reflection filter unit, and the second reflection filter The units are arranged linearly in sequence, and the gain medium is arranged between the common reflection filter unit and the first reflection filter unit; The first reflection filtering unit includes a first reflection filtering waveband area and a first transmission waveband area; A part of the energy of the laser is reflected and filtered by the first reflection filter band region, and another part of the energy of the laser is transmitted from the first transmission band region to the second reflection filter unit, and passes through the second reflection filter unit. The reflection filter unit transmits again from the first transmission band area to the common reflection filter unit after reflection. The dual-frequency light source according to claim 2, wherein the common reflection filtering unit adopts a partial reflection filtering unit for partially reflecting and filtering the laser and outputting the first single-frequency laser and the second single-frequency laser. Single frequency laser. The dual-frequency light source according to claim 3, wherein a first pump light coupling unit is provided between the pump unit and the common reflection filter unit for coupling the pump light into the The first resonant cavity and the second resonant cavity; the first single-frequency laser and the second single-frequency laser output by the common reflection filtering unit are output through the first pump light coupling unit. The dual-frequency light source according to claim 3, wherein a second pump light coupling unit is provided in the first resonant cavity or the second resonant cavity for coupling the pump light into the first resonant cavity. A resonant cavity and a second resonant cavity. The dual-frequency light source according to claim 2, wherein the dual-frequency light source further comprises a third pump light coupling unit, which is arranged in the first resonant cavity or the second resonant cavity, and is used to connect the Pump light is input through the side end of the first resonant cavity or the second resonant cavity; The dual-frequency light source further includes an output unit, which is arranged in a common part of the first resonant cavity and the second resonant cavity, and is used to output the first single-frequency laser and the second single-frequency laser. The dual-frequency light source according to claim 1, wherein the first resonant cavity and the second resonant cavity have a ring cavity structure, and the dual-frequency light source further comprises a fourth pump light coupling unit and a first coupler And the second coupler; The first end of the fourth pump light coupling unit is connected to the pump unit, the second end of the fourth pump light coupling unit is connected to the first coupler, and the fourth pump light coupling unit The third end of is connected to the common reflection filter unit; The first reflection filtering unit and the second reflection filtering unit are connected in parallel between the first coupler and the second coupler, and the common reflection filtering unit is connected to the second coupler and the fourth pump Between the third end of the Pu optical coupling unit. 8. The dual-frequency light source according to claim 7, wherein the dual-frequency light source comprises an output unit disposed between the second coupler and the common reflection filter unit; Alternatively, the dual-frequency light source includes two output units, which are respectively arranged on two parallel branches between the first coupler and the second coupler; An isolator is respectively provided on the two parallel branches between the first coupler and the second coupler, and the directions of the two isolators are the same or opposite; Alternatively, an isolator is provided on the common section between the fourth pump light coupling unit and the first coupler; Alternatively, an isolator is provided on the common section between the fourth pump light coupling unit and the second coupler. 8. The dual-frequency light source of claim 7, wherein the dual-frequency light source further comprises a first circulator, a second circulator, and a third circulator; The first end of the first circulator is connected to the first coupler, the second end of the first circulator is connected to the first reflection filter unit, and the third end of the first circulator is connected to the Second coupler The first end of the second circulator is connected to the first coupler, the second end of the second circulator is connected to the second reflection filter unit, and the third end of the second circulator is connected to the Second coupler The first end of the third circulator is connected to the second coupler, the second end of the third circulator is connected to the common reflection filter unit, and the third end of the third circulator is connected to the pump Puguang coupling unit. The dual-frequency light source according to claim 1, wherein the dual-frequency light source further comprises an isolation unit arranged on the output path of the first single-frequency laser and the second single-frequency laser. The dual-frequency light source according to claim 1, wherein the dual-frequency light source further comprises a tuning unit, and the tuning unit is connected to the first reflection filter unit for adjusting the Center wavelength and/or bandwidth to obtain a tunable first single-frequency laser; and/or The tuning unit is connected to the second reflection filter unit and is used to adjust the center wavelength and/or bandwidth of the second reflection filter unit to obtain a tunable second single-frequency laser; and/or The tuning unit is connected to the common reflection filter unit and is used to obtain the tunable first single-frequency laser and the tunable second single-frequency laser simultaneously. The dual-frequency light source according to any one of claims 1 to 11, wherein the common reflection filter unit is an integrated structure capable of filtering and reflecting the laser light. The dual-frequency light source according to any one of claims 1 to 11, wherein the common reflection filter unit comprises a common mirror, and a common filter module arranged in the reflection direction of the common mirror. The dual-frequency light source according to any one of claims 1 to 11, wherein the first reflection filtering unit is an integrated structure capable of filtering and reflecting the laser; and the second reflection filtering unit is capable of An integrated structure for filtering and reflecting the laser. The dual-frequency light source according to any one of claims 1 to 11, wherein the first reflection filtering unit comprises a first reflection mirror, and a first filtering module arranged in the reflection direction of the first reflection mirror ； The second reflection filtering unit includes a second reflection mirror, and a second filtering module arranged in a reflection direction of the second reflection mirror.