WO2023226752A1 - Dual-wavelength laser and relay amplifier - Google Patents

Abstract

A dual-wavelength laser and a relay amplifier, belonging to the technical field of optical fiber communications. The dual-wavelength laser comprises a three-level laser module (1), a four-level laser module (2), and a first pumping source (3). The gain mediums of the three-level laser module (1) and the four-level laser module (2) are both optical fibers at least doped with ytterbium ions. The first pumping source (3) outputs to the three-level laser module (1) a pumped light of a first wavelength; the three-level laser module (1) absorbs the pumped light of the first wavelength, radiates light of a second wavelength, and outputs to the four-level laser module (2) the unused first pumped light among pumped light of the first wavelength. The four-level laser module (2) absorbs the first pumped light and radiates light of a third wavelength. Thus, laser having two different wavelengths can be output by using one dual-wavelength laser.

Description

Dual wavelength lasers and relay amplifiers

This application claims priority to the Chinese patent application with application number 202210571261.3 and the invention name "Dual-Wavelength Laser and Relay Amplifier" submitted on May 24, 2022, the entire content of which is incorporated into this application by reference.

Technical field

This application relates to the field of optical fiber communication technology, and in particular to a dual-wavelength laser and relay amplifier.

Background technique

In single-mode optical fiber communication, when transmitting over long distances, the signal light intensity in the optical fiber will continue to be lost as the transmission distance continues to increase. The lower signal-to-noise ratio will make the signal quality worse, and even the signal will eventually be submerged. In the noise, therefore, a relay amplifier is needed to amplify the signal light.

In related technologies, when signal light of multiple bands is transmitted in a single-mode optical fiber, the signal light of multiple bands requires a relay amplifier for amplification. Relay amplifiers all require pump sources to provide pump light. Signal light in different wavelength bands may require different pump lights, so pump sources of multiple wavelengths are needed. For example, single-mode optical fiber transmits short (S) band, conventional (C) band and long (L) band signal light. The S-band signal light uses a 1050nm pump source, and the C-band signal The light needs to use a 980nm pump source, and the L-band signal light needs to use a 980nm pump source. In this way, when transmitting signal light of multiple bands in a single-mode fiber, lasers of multiple wavelengths need to be used simultaneously to provide pump light.

Contents of the invention

This application provides a dual-wavelength laser and a relay amplifier. The dual-wavelength laser can output two different wavelengths of light, so that one laser can provide two different wavelengths of light.

In a first aspect, this application provides a dual-wavelength laser. The dual-wavelength laser includes a three-level laser module, a four-level laser module and a first pump source; the gain medium of the three-level laser module is at least doped An optical fiber with ytterbium ions, the gain medium of the four-level laser module is an optical fiber doped with at least ytterbium ions; the first pump source is used to output pump light of a first wavelength to the three-level laser module; The three-level laser module is used to absorb the pump light of the first wavelength, radiate the light of the second wavelength, and output the unused first pump of the pump light of the first wavelength to the four-level laser module. pump light; the four-level laser module is used to absorb the first pump light and radiate light of the third wavelength.

In the solution shown in this application, the dual-wavelength laser includes a three-level laser module, a four-level laser module and a first pump source. The three-level laser module generates light of the second wavelength using a three-level system. The four-level laser module The laser module generates the third wavelength of light using a four-level system. By cascading the four-level laser module after the three-level laser module, the remaining pump light of the three-level laser module is provided to the four-level laser module, thereby improving the pump light utilization rate.

In an example, the three-level laser module includes a first gain medium, a first wavelength division multiplexer (WDM) and a first reflection unit, the first gain medium is located between the first WDM and the first reflection unit. between the first reflection units; the first WDM is used to output the pump light of the first wavelength to the first gain medium; the first gain medium is used to absorb the pump light of the first wavelength and output it in both directions. The light of the second wavelength is transmitted to the first reflection unit. Output the unused first pump light in the pump light of the first wavelength; the first reflection unit is used to reflect and output the light of the second wavelength to the first gain medium, and transmit the first pump light to The four-level laser module; the first WDM is also used to output the light of the second wavelength output by the first gain medium.

In the solution shown in this application, the three-level laser module includes a first gain medium, a first WDM and a first reflection unit. The three-level laser module includes few devices and has a simple structure.

In one example, the three-level laser module further includes a second reflective unit, the reflectivity of the second reflective unit for the light of the second wavelength is lower than the reflection of the first reflective unit for the light of the second wavelength. rate, the transmittance of the second reflective unit for the light of the second wavelength is higher than the reflectivity of the light of the second wavelength; the first WDM is located between the first gain medium and the second reflective unit; The first WDM is also used to output the light of the second wavelength to the second reflection unit; the second reflection unit is used to combine the first gain medium and the first reflection unit with the light of the second wavelength. Selected resonant cavity.

In the solution shown in this application, in the three-level laser module, a resonant cavity is composed of a high-reflection device, a low-reflection device and a first gain medium. The resonant cavity can select the light of the second wavelength, and The light of the second wavelength can be made to travel back and forth into the resonant cavity multiple times, so that the power of the light of the second wavelength is relatively high.

In one example, the four-level laser module includes a third reflection unit and a second gain medium; the third reflection unit is used to transmit and output the first output of the three-level laser module to the second gain medium. Pump light; the second gain medium is used to absorb the first pump light and bidirectionally output light of the third wavelength; the third reflection unit is also used to reflect the light of the third wavelength.

In the solution shown in this application, the four-level laser module includes a third reflection unit and a second gain medium. The four-level laser module includes few devices and has a simple structure.

In an example, the dual-wavelength laser further includes a second pump source, and the four-level laser module further includes a second WDM; the second gain medium is located between the third reflection unit and the second WDM; The second pump source is used to output the pump light of the fourth wavelength to the second WDM; the second WDM is used to output the pump light of the fourth wavelength to the second gain medium; the second gain medium is used to absorb the first pump light and the pump light of the fourth wavelength, and bidirectionally output the light of the third wavelength; the second WDM is also used to output the third wavelength of light output by the second gain medium. Light.

In the solution shown in this application, the dual-wavelength laser includes a first pump source and a second pump source. The first pump source directly provides pump light to the three-energy level laser module, and the second pump source directly provides pump light to the four-energy level laser module. The laser module provides pump light and adopts a bidirectional pumping method. By adjusting the power of the first pump source and the second pump source, the power of the dual-wavelength laser output laser can be flexibly adjusted.

In an example, the four-level laser module includes a third reflective unit, a second gain medium and a second WDM; the second gain medium is located between the third reflective unit and the second WDM; the second WDM Used to output the first pump light output by the three-level laser module to the second gain medium; the second gain medium is used to absorb the first pump light and bidirectionally output light of the third wavelength; The third reflection unit is configured to reflect the light of the third wavelength; the second WDM is further configured to output the light of the third wavelength output by the second gain medium.

In an example, the dual-wavelength laser further includes a first isolation module; the first isolation module is located between the three-level laser module and the four-level laser module; the first isolation module is used to make the third Pump light of one wavelength passes through, and the light generated by the three-level laser module and the light generated by the four-level laser module are prevented from passing through.

In the solution shown in this application, by arranging the first isolation module, the three-level laser module and the four-level laser module will not affect each other.

In one example, the dual-wavelength laser includes a second pump source; the second pump source is used to output pump light of a fourth wavelength to the second WDM; and the second gain medium is used to absorb the The first pump light and the pump light of the fourth wavelength bidirectionally output the light of the third wavelength, and output the unused second pump light of the pump light of the fourth wavelength to the third reflection unit; The third reflection unit is also used to output the second pump light to the three-level laser module.

In the solution shown in this application, the dual-wavelength laser also includes a second pump source. The second pump source directly provides pump light to the four-level laser module. The four-level laser module can also convert the second pump source into The unused second pump light is provided to the three-level laser module, so that the power of the pump light can be increased as much as possible, and the high-power pump light is prevented from being completely absorbed in a short distance, maximizing the pump improvement. Light utilization.

In an example, the dual-wavelength laser further includes a second isolation module and a third isolation module; the second isolation module is located between the second WDM and the three-level laser module, and the second isolation module is used to, The pump light of the first wavelength and the pump light of the fourth wavelength are allowed to pass, and the light generated by the three-level laser module and the light generated by the four-level laser module are prevented from passing; the third isolation module is located on the Between the three-level laser module and the third reflection unit, the third isolation module is used to allow the pump light of the first wavelength and the pump light of the fourth wavelength to pass through, and prevent the three-level laser module. The generated light passes through the light generated by the four-level laser module.

In the solution shown in this application, by arranging the second isolation module and the third isolation module, the three-energy level laser module and the four-energy laser module will not affect each other.

In one example, the four-level laser module further includes a fourth reflective unit, the reflectivity of the fourth reflective unit for the light of the third wavelength is lower than the reflection of the third reflective unit for the light of the third wavelength. rate, the transmittance of the fourth reflective unit to the light of the third wavelength is higher than the reflectivity of the light of the third wavelength; the second WDM is located between the second gain medium and the fourth reflective unit; The fourth reflection unit is used to form a resonant cavity that selects the light of the third wavelength with the third reflection unit and the second gain medium.

In the solution shown in this application, in the four-level laser module, a resonant cavity is composed of a high-reflection device, a low-reflection device and a second gain medium. The resonant cavity can select the light of the third wavelength, and The light of the third wavelength can be caused to travel back and forth into the resonant cavity multiple times, so that the power of the light of the third wavelength is relatively high.

In an example, the pump light of the first wavelength is multi-mode pump light.

In an example, the fourth wavelength of pump light is multi-mode pump light.

In an example, the first wavelength is 915nm or 975nm, the second wavelength ranges from 970nm to 980nm, and the third wavelength ranges from 1030nm to 1100nm.

In an example, both the first reflection unit and the second reflection unit are reflective fiber Bragg gratings.

In an example, both the third reflection unit and the fourth reflection unit are reflective fiber Bragg gratings.

In a second aspect, the present application provides a relay amplifier, which includes a third WDM, a third gain medium, a fourth WDM, a fourth gain medium, and any possible implementation method as in the first aspect or any one thereof. The dual-wavelength laser described in; the third WDM is used to couple the light of the second wavelength to the third gain medium; the third gain medium is used to absorb the light of the second wavelength and pass through the relay amplifier Amplify the signal light of the first wavelength band; the fourth WDM is used to couple the light of the third wavelength to the fourth gain medium; the fourth gain medium is used to absorb the light of the third wavelength, and The signal light of the second band is amplified following the amplifier.

In the solution shown in this application, when the relay amplifier amplifies signal light of two different wavelengths, a dual-wavelength laser can be used as a pump source, which reduces the implementation complexity of the relay amplifier.

Description of the drawings

Figure 1 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 2 is a schematic diagram of the working energy level of a ytterbium ion-doped laser provided by an exemplary embodiment of the present application;

Figure 3 is an absorption and radiation spectrum diagram of ytterbium ions provided by an exemplary embodiment of the present application;

Figure 4 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 5 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 6 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 7 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 8 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 9 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 10 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 11 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 12 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 13 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 14 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 15 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 16 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 17 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 18 is a schematic structural diagram of a dual-wavelength laser provided by an exemplary embodiment of the present application;

Figure 19 is a schematic structural diagram of a relay amplifier provided by an exemplary embodiment of the present application;

Figure 20 is a schematic structural diagram of a relay amplifier provided by an exemplary embodiment of the present application;

Figure 21 is a schematic structural diagram of a relay amplifier provided by an exemplary embodiment of the present application;

Figure 22 is a schematic structural diagram of a relay amplifier provided by an exemplary embodiment of the present application.

Illustration
1. Three-level laser module; 2. Four-level laser module; 3. First pump source; 4. Second pump source;
5. The first isolation module; 6. The second isolation module; 7. The third isolation module;
11. The first gain medium; 12. The first WDM; 13. The first reflection unit; 14. The second reflection unit;
21. The third reflection unit; 22. The second gain medium; 23. The second WDM; 24. The fourth reflection unit;
31. The first pump unit; 32. The second pump unit; 41. The third pump unit; 42. The fourth pump unit;
01. The third WDM; 02. The third gain medium; 03. The fourth WDM; 04. The fourth gain medium; 05. Power splitter; 06. The fifth WDM; 07. The fifth gain medium; 08. The sixth WDM ;09. The seventh WDM.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

Some terms and concepts involved in the embodiments of this application are explained below.

1. Double-clad fiber consists of core, inner cladding, outer cladding and protective layer. Among them, the fiber core serves as the laser transmission channel, and the inner cladding serves as the pump light channel, which is multi-mode for the pump light. The outer cladding is made of polymer with a refractive index smaller than that of the inner cladding. It is made of physical materials. In this way, an optical waveguide with large cross-section and large numerical aperture is formed between the inner cladding and the outer cladding, which can allow large numerical aperture, large cross-section and multi-mode high-power pump light to be coupled into the optical fiber. The protective layer Can be hard plastic, used to protect optical fibers.

2. A three-energy level system, including the ground state E ₀ , the metastable state E ₁ and the high energy level E ₂ . The lower energy level is the ground state E ₀ and the upper energy level is the metastable state E ₁ . The luminescence process is: under the action of the pump source, the particles in the ground state E ₀ are pumped to the high energy level E _2. At the high energy level E ₂ , the particles make a non-radiative transition to the metastable state E ₁ , and the particles accumulate in the metastable state E 1. In state E ₁ , when the difference between the number of particles in the metastable state E ₁ and the number of particles in the ground state E ₀ meets the threshold condition, the particles in the metastable state E ₁ transition to the ground state E ₀ and emit light. During the luminescence process of the three-level system, a considerable number of particles in the ground state E ₀ are always preserved.

3. Four-level system, including ground state E ₀ , excited state E ₁ , metastable state E ₂ and high energy level E ₂ . The lower energy level is the excited state E ₁ and the upper energy level is the metastable state E ₂ . The luminescence process is: under the action of the pump source, the particles in the ground state E ₀ are pumped to the high energy level E ₃ , the particles transition to the metastable state E ₂ without radiation, and the particles accumulate in the metastable state E _2. When the substable state E 2 When the difference between the number of particles in the stable state E ₂ and the number of particles in the excited state E ₁ meets the threshold condition, the particles in the metastable state E ₂ transition to the excited state E ₁ and emit light.

The background of the embodiments of the present application is described below.

In single-mode optical fiber communication, when transmitting over long distances, the signal strength in the optical fiber will continue to lose as the transmission distance continues to increase. A too low signal-to-noise ratio will make the signal quality worse, and even cause the signal to eventually be submerged. In noise, therefore, a relay amplifier is needed to amplify the signal strength.

In related technologies, when signal light of multiple bands is transmitted in a single-mode optical fiber, the signal light of multiple bands requires a relay amplifier for amplification. Relay amplifiers all require pump sources to provide pump light. Signal light in different wavelength bands may require different pump lights, so pump sources of multiple wavelengths are needed. For example, to transmit S-band, C-band and L-band signal light in single-mode fiber, the S-band signal light needs to use a 1050nm pump source, the C-band signal light needs to use a 980nm pump source, and the L-band signal light needs to use a 980nm pump source. A 980nm pump source is required.

The embodiment of the present application provides a dual-wavelength laser. The dual-wavelength capable laser can output two different wavelengths of light. The two different wavelengths of light can be used as pump light. In this way, when two different wavelengths of pump light are required, When priming the source, only one dual-wavelength laser is used.

The structure of the dual-wavelength laser in the embodiment of the present application is described below.

Figure 1 exemplarily provides a schematic structural diagram of a dual-wavelength laser. Referring to Figure 1, the dual-wavelength laser includes a three-level laser module 1, a four-level laser module 2 and a first pump source 3.

In the three-level laser module 1, the particle number inversion to generate laser is realized through a three-level system. The gain medium of the three-level laser module 1 is an optical fiber doped with at least ytterbium ions.

The realization of particle number inversion to generate laser in the four-level laser module 2 is achieved through a four-level system. The gain medium of the four-level laser module 2 is an optical fiber doped with at least ytterbium ions.

The first pump source 3 can output the pump light of the first wavelength, and inputs the pump light of the first wavelength to the three-level laser module 1 . The three-level laser module 1 can absorb the pump light of the first wavelength, radiate the light of the second wavelength, the light of the second wavelength is a single-mode laser, and output the pump light of the first wavelength to the four-level laser module 2 The unused pump light is called the first pump light. The four-level laser module 2 absorbs the first pump light and radiates light of a third wavelength, and the light of the third wavelength is a single-mode laser. In this way, the dual-wavelength laser can radiate light of the second wavelength and light of the third wavelength.

It should be noted that the three-level laser module 1 generates laser through a three-level system. The three-level system requires a high particle number inversion, and there will be more pump light remaining. The cascaded four-level laser module 2 generates laser light through a four-level system. Now, the four-level system requires less particle number inversion than the three-level system, so the four-level laser module 2 can use the remaining pump light of the three-level laser module 1 to improve pump utilization.

Figure 2 provides a schematic diagram of the operating energy levels of a laser doped with ytterbium ions. Referring to Figure 2, there are 7 energy levels in ytterbium ions, and the 7 energy levels are a to g energy levels from low to high. Among them, when the first wavelength, the second wavelength and the third wavelength are 915nm, 977nm and greater than 1000nm and less than 2000nm respectively, when the 915nm pump light pumps the 977nm light lasing, the participating energy levels are g, e and a, when the 915nm pump light pumps the light greater than 1000nm and less than 2000nm, there are a total of 4 energy levels involved. For example, the energy levels corresponding to 1069nm are g, e, d and a.

Figure 3 provides ytterbium ion absorption and radiation spectra. In Figure 3, the absorption peaks of ytterbium ions are at 915nm and 975nm, and the radiation peaks are at 976nm and 1025nm. In Figure 3, at the 976nm position, the absorption and emission line segments overlap.

Referring to Figure 3, in an example, the first wavelength is 915nm or 975nm, the second wavelength ranges from 970nm to 980nm, and the third wavelength ranges from 1030nm to 1100nm. For example, the second wavelength is 976nm and the third wavelength is 1050nm.

In an example, the pump light of the first wavelength is a multi-mode pump light, the multi-mode pump light is a single longitudinal mode, and the transverse multi-mode pump light is a pump light.

In the embodiment of the present application, in the dual-wavelength laser shown above, the second wavelength light generated by the three-level laser module 1 may be output to the four-level laser module 2, affecting the four-level laser module 2. , the third wavelength light generated by the four-level laser module 2 may also be output to the three-level laser module 1, affecting the three-level laser module 1.

In order to reduce the influence between the three-level laser module 1 and the four-level laser module 2, an isolation module can be provided between the three-level laser module 1 and the four-level laser module 2. Specifically, referring to the dual-wavelength laser shown in FIG. 4 , a first isolation module 5 is provided between the three-level laser module 1 and the four-level laser module 2 . The first isolation module 5 can allow the pump light of the first wavelength to pass through, and can prevent at least the light of the third wavelength from passing through.

Optionally, the first isolation module 5 is a two-port device, which includes an input port and an output port.

In one example, the first isolation module 5 may be an isolator, realizing one-way transmission of broad-spectrum optical signals. For example, the optical fiber used in the isolator is a multi-mode optical fiber with a numerical aperture (NA) of 105/125um = 0.22, and a magneto-optical crystal is used to realize one-way transmission of a wide-spectrum optical signal. In the embodiment of the present application, the wide-spectrum The wavelength range of the optical signal can be 950~1100nm, "105" means the core diameter is 105μm, and "125" means the cladding diameter of the fiber is 125μm. Specifically, the direction of the isolator is set to transmit light in the direction from the three-level laser module 1 to the four-level laser module 2 and prevent the light in the direction from the four-level laser module 2 to the three-level laser module 1 from passing through. In this way, when the first isolation module 5 uses an isolator, the light of the third wavelength generated by the four-level laser module 2 will not be output to the three-level laser module 1 and will not affect the three-level laser module 1 .

In another example, the first isolation module 5 may be a filter. For example, the filter can realize light intensity scattering in a certain band. When the first wavelength, second wavelength and third wavelength are 915nm, 976nm and 1050nm respectively, the band can be 950~1100nm. The filter adopts The fiber is a 105/125um multi-mode fiber with NA=0.22. On the multi-mode fiber, long period fiber grating is used to write to achieve light intensity scattering of 950~1100nm. In this way, when the first isolation module 5 uses a filter, the light of the second wavelength generated by the three-level laser module 1 will not be output to the four-level laser module 2 and will not affect the four-level laser module 2 and the four-level laser module 2. The light of the third wavelength generated by the laser module 2 will not be output to the three-level laser module 1 and will not affect the three-level laser module 1 .

In the embodiment of the present application, the three-level laser module 1 has multiple structures, and two possible structures are provided as follows.

In an example, in a dual-wavelength laser, the three-level laser module 1 includes a first gain medium 11, a first WDM 12, and a first reflection unit 13. Figure 5 exemplarily provides a schematic structural diagram of a dual-wavelength laser. Referring to Figure 5, the first gain medium 11 is located between the first WDM 12 and the first reflection unit 13. The first gain medium 11 is an optical fiber doped with at least ytterbium ions. When the first gain medium 11 is doped with ytterbium ions, , it may also be doped with other ions, which is not limited in the embodiments of this application.

The first WDM 12 is connected to the first pump source 3 , and the pump light of the first wavelength is input to the first gain medium 11 through the first WDM 12 . The first gain medium 11 absorbs the pump light of the first wavelength, outputs the light of the second wavelength bidirectionally, and outputs the first pump light of the pump light of the first wavelength to the first reflection unit 13, here “bidirectional output” It means that the first gain medium 11 outputs the light of the second wavelength to the first WDM 12 and outputs the light of the second wavelength to the first reflection unit 13 . The first WDM 12 may also output the received light of the second wavelength.

The first reflective unit 13 transmits the pump light of the first wavelength, reflects the light of the second wavelength, and has a relatively high reflectivity of the light of the second wavelength, and is a highly reflective device. The first reflection unit 13 transmits the first pump light to the four-level laser module 2 . The four-level laser module 2 absorbs the first pump light and radiates light of the third wavelength. The first reflection unit 13 can also reflect and output the light of the second wavelength to the first gain medium 11 .

In another example, in a dual-wavelength laser, a resonant cavity is formed by a high-reflection device and a low-reflection device in the three-level laser module 1 to complete the screening of light of the second wavelength. Figure 6 exemplarily provides a dual-wavelength laser. Structural diagram. Referring to Figure 6, the three-level laser module 1 includes a first gain medium 11, a first WDM 12, a first reflection unit 13 and a second reflection unit 14. The first reflection unit 13 has a higher reflectivity for light of the second wavelength than the first reflection unit 13. The reflectivity of the second reflective unit 14 to the light of the second wavelength and the transmittance of the second reflective unit 14 to the light of the second wavelength are higher than the reflectivity of the second reflective unit 14 to the light of the second wavelength. The first reflective unit 13 is a high-reflective device, and the second reflective unit 14 is a low-reflective device. The first WDM 12 and the second reflection unit 14 are connected through optical fibers.

The first WDM 12 outputs light of the second wavelength to the second reflective unit 14. The second reflective unit 14 transmits most of the received light of the second wavelength and reflects a small part of the light of the second wavelength to the first gain. Medium 11. The first reflective unit 13 forms a resonant cavity with the first gain medium 11 and the second reflective unit 14, and the resonant cavity can realize the selection of light of the second wavelength.

In the dual-wavelength laser shown in Figure 6, since there is a resonant cavity in the three-level laser module 1, the light of the second wavelength passes through the first gain medium 11 multiple times, so the power of the light of the second wavelength can be made higher.

In one example, the first gain medium 11 can be an optical fiber doped with ytterbium ions, and can be connected with 6/125DCF low loss to realize the transmission of single-mode signals in the fiber core and multi-mode signals in the inner cladding. Low-loss connection, multi-mode signal refers to the pump optical signal.

In one example, the first WDM 12 may be a three-port device, specifically a three-port optical fiber combiner of pump light and signal light, which includes a pump light input port, a signal light transmission port, and A common transmission port for signal light and pump light. When the first WDM 12 is a three-port device, it means that there is one pump source, that is to say, the first pump source 3 outputs one pump light to the three-level laser module 1 . For example, the first pump source 3 is a 915 nm multi-mode pump laser (laser diode, LD), or a 975 nm multi-mode pump laser.

In another example, the first WDM 12 may also be a four-port device, specifically a (2+1)x1 pump light/signal optical fiber combiner, which includes two pump light input ports and one signal An optical transmission port and a common transmission port for signal light and pump light. When the first WDM12 is a four-port device, it means that there are two pump sources. That is to say, the first pump source 3 outputs two pump lights to the three-level laser module 1. The two pump lights form the components described above. the first wavelength of The wavelength of the two pump lights is the first wavelength, and the power of the two pump lights may be equal or unequal. For example, the first pump source 3 includes a first pump unit 31 and a second pump unit 32. The first pump unit 31 and the second pump unit 32 are both 915 nm multi-mode pump lasers. Both the pump unit 31 and the second pump unit 32 are connected to the first WDM 12, or the first pump source 3 includes the first pump unit 31 and the second pump unit 32, and the first pump unit 31 and the second pump unit 32 are connected to the first WDM 12. The pump units 32 are both 975nm multi-mode pump lasers. The first pump unit 31 and the second pump unit 32 are both connected to the first WDM 12. See the dual-wavelength laser shown in Figure 7.

In the port of the first WDM12, the pump light input port can be a 105/125 μm, NA=0.22 multi-mode optical fiber. “105” indicates that the core diameter is 105 μm, and “125” indicates that the cladding diameter of the optical fiber is 125 μm. The signal light transmission port can be a 6/125μm double cladding fiber (DCF), and the common transmission port for the signal light and pump light can be a 20/125 DCF. "6" means the core diameter is 6μm, "125" means the outer cladding diameter of the fiber is 125μm, the typical inner cladding diameter is 105μm, and "20" means the core diameter is 20μm.

Optionally, the first reflection unit 13 is a reflective fiber Bragg grating (fiber bragg grating, FBG), and is an FBG with high reflectivity. The first reflection unit 13 may be obtained by writing in a single-mode optical fiber, and the embodiment of the present application does not limit the type of single-mode optical fiber.

The second reflective unit 14 is also a reflective FBG, and is a low reflectivity FBG. The second reflective unit 14 may be obtained by writing in DCF.

In the embodiment of the present application, the four-level laser module 2 has multiple structures, and multiple possible structures are provided as follows.

In an example, in a dual-wavelength laser, the four-level laser module 2 includes a third reflection unit 21 and a second gain medium 22. Figure 8 exemplarily provides a schematic structural diagram of the dual-wavelength laser. Referring to FIG. 8 , the third reflective unit 21 transmits the pump light of the first wavelength and reflects the light of the third wavelength. The reflectivity of the light of the third wavelength is relatively high, and it is a highly reflective device. The third reflection unit 21 is connected to the three-level laser module 1. Specifically, the third reflection unit 21 is connected to the first reflection unit 13 of the three-level laser module 1 through an optical fiber. The third reflection unit 21 is also connected to the second gain medium 22 , and the second gain medium 22 is connected to the output port of the third wavelength light in the dual-wavelength laser.

The three-level laser module 1 outputs unused first pump light. The first pump light is incident on the third reflection unit 21 , and the third reflection unit 21 transmits the first pump light and inputs the first pump light into the second gain medium 22 . The second gain medium 22 absorbs the first pump light and radiates light of the third wavelength. The light of the third wavelength is bidirectionally output. Here, the “bidirectional output” points to the third reflection unit 21 to output the light of the third wavelength, and to The output port of the dual-wavelength laser outputs the third wavelength of light. After receiving the light of the third wavelength, the third reflection unit 21 reflects the light of the third wavelength, and inputs the light of the third wavelength into the second gain medium 22 again, thereby amplifying the light of the third wavelength again. The output port of the dual-wavelength laser outputs light of a third wavelength, and the light of the third wavelength can be used as a pump source of the relay amplifier. The embodiments of this application do not limit the use of light of the third wavelength.

In another example, pump light can also be directly provided to the four-level laser module 2 . Referring to the dual-wavelength laser shown in FIG. 9 , the dual-wavelength laser also includes a second pump source 4 , and the four-level laser module 2 includes a third reflection unit 21 , a second gain medium 22 and a second WDM 23 . The second gain medium 22 is located between the third reflection unit 21 and the second WDM 23 . The second WDM 23 is located between the second gain medium 22 and the second pump source 4 .

The second pump source 4 may output pump light of a fourth wavelength, and the fourth wavelength may be the same as the first wavelength, or may be different from the first wavelength. The second pump source 4 outputs the pump light of the fourth wavelength to the second WDM 23 . The second gain medium 22 absorbs the first pump light and the pump light of the fourth wavelength, and radiates light of the third wavelength. The light of the third wavelength is bidirectionally output, where the “bidirectional output” is directed to the output of the third reflection unit 21 The light of the third wavelength is output to the second WDM 23 . The light of the third wavelength will be incident on the third reflection unit 21 and the second WDM 23 , and the third reflection unit 21 receives the third wavelength After receiving the light, the light of the third wavelength is reflected, and the light of the third wavelength is input into the second gain medium 22 again, thereby amplifying the light of the third wavelength again. The second WDM 23 also outputs a third wavelength of light as the third wavelength of light output by the dual wavelength laser.

In the dual-wavelength laser shown in Figure 9, the presence of the second pump source 4 can make the power of the pump light used by the four-level laser module 2 relatively high, thereby making the power of the third wavelength light relatively high. Moreover, by adopting the bidirectional pumping mode, the output power of the light of the second wavelength and the light of the third wavelength can be flexibly adjusted by adjusting the power of the first pump source 3 and the second pump source 4 .

In another example, in a dual-wavelength laser, a resonant cavity is formed by a high-reflection device and a low-reflection device in the four-level laser module 2 to complete the screening of light of the third wavelength. Figure 10 provides an exemplary dual-wavelength laser. Structural diagram. Referring to FIG. 10 , the four-level laser module 2 includes a third reflection unit 21 , a second gain medium 22 and a fourth reflection unit 24 . The reflectivity of the third reflective unit 21 to the light of the third wavelength is higher than the reflectivity of the fourth reflective unit 24 to the light of the third wavelength. The transmittance of the fourth reflective unit 24 to the light of the third wavelength is higher than that of the fourth reflective unit 24 to the light of the third wavelength. Reflectivity of wavelength of light. The third reflective unit 21 is a high-reflective device, and the fourth reflective unit 24 is a low-reflective device. The second gain medium 22 is located between the third reflective unit 21 and the fourth reflective unit 24 . The third reflection unit 21 is connected to the three-level laser module 1, and the fourth reflection unit 24 is connected to the output port of the dual-wavelength laser.

The three-level laser module 1 outputs unused first pump light. The first pump light is incident on the third reflection unit 21 , and the third reflection unit 21 transmits the first pump light and inputs the first pump light into the second gain medium 22 . The second gain medium 22 absorbs the first pump light and radiates light of the third wavelength. The light of the third wavelength is bidirectionally output. Here, the “bidirectional output” points to the third reflection unit 21 to output the light of the third wavelength, and to The fourth reflection unit 24 outputs light of the third wavelength. After receiving the light of the third wavelength, the third reflection unit 21 reflects the light of the third wavelength, and inputs the light of the third wavelength into the second gain medium 22 again, thereby amplifying the light of the third wavelength again. The light of the third wavelength is incident on the fourth reflection unit 24, and the fourth reflection unit 24 transmits most of the light of the third wavelength, so that the light of the third wavelength is output from the output port of the dual-wavelength laser. The fourth reflective unit 24 reflects a small portion of the light of the third wavelength to the second gain medium 22 . The fourth reflective unit 24 , the second gain medium 22 and the third reflective unit 21 form a resonant cavity. The resonant cavity makes the light of the third wavelength The light travels back and forth multiple times, which not only makes the dual-wavelength laser output a relatively high power of the third wavelength of light, but also selects the accurate third wavelength of light.

In another example, in a dual-wavelength laser, a resonant cavity is formed in the four-level laser module 2 by a high-reflection device and a low-reflection device to complete the screening of light of the third wavelength, and the four-level laser module 2 corresponds to Direct pump light, Figure 11 exemplarily provides a schematic structural diagram of the dual-wavelength laser. Referring to FIG. 11 , the dual-wavelength laser also includes a second pump source 4 , and the four-level laser module 2 includes a third reflection unit 21 , a second gain medium 22 , a second WDM 23 and a fourth reflection unit 24 .

Corresponding to the light of the third wavelength, the third reflective unit 21 is a high-reflective device, and the fourth reflective unit 24 is a low-reflective device. The second gain medium 22 is located between the third reflective unit 21 and the second WDM 23 , the second WDM 23 is located between the second gain medium 22 and the fourth reflective unit 24 , and is located between the second gain medium 22 and the second pump source 4 between. The third reflection unit 21 is connected to the three-level laser module 1, and the fourth reflection unit 24 is connected to the output port of the dual-wavelength laser.

The three-level laser module 1 outputs unused first pump light. The first pump light is incident on the third reflection unit 21 , and the third reflection unit 21 transmits the first pump light and inputs the first pump light into the second gain medium 22 . The second gain medium 22 absorbs the first pump light and radiates light of the third wavelength. The light of the third wavelength is bidirectionally output. Here, the “bidirectional output” points to the third reflection unit 21 to output the light of the third wavelength, and to The second WDM 23 outputs light of the third wavelength. After receiving the light of the third wavelength, the third reflection unit 21 reflects the light of the third wavelength, and inputs the light of the third wavelength into the second gain medium 22 again, thereby amplifying the light of the third wavelength again. The light of the third wavelength is incident on the second WDM23, and the second WDM23 outputs the third wave The long light reaches the fourth reflection unit 24 . The fourth reflection unit 24 transmits most of the light of the third wavelength, so that the light of the third wavelength is output from the output port of the dual-wavelength laser. The fourth reflective unit 24 reflects a small part of the light of the third wavelength, and the small part of the light of the third wavelength is input to the second gain medium 22 through the second WDM 23 . The fourth reflective unit 24 and the third reflective unit 21 and the second The gain medium 22 forms a resonant cavity, which allows the light of the third wavelength to travel back and forth multiple times, which not only allows the dual-wavelength laser to output a relatively high power of the light of the third wavelength, but also selects the accurate light of the third wavelength.

In another example, in a dual-wavelength laser, the third reflection unit 21 in the four-level laser module 2 is located at an end away from the three-level laser module 1. Figure 12 exemplarily provides a schematic structural diagram of the dual-wavelength laser. . Referring to Figure 12, the four-level laser module 2 includes a third reflection unit 21, a second gain medium 22 and a second WDM 23. The second WDM 23 is a three-port device, see the description below. The second gain medium 22 is located between the third reflection unit 21 and the second WDM 23 . The second WDM 23 is connected to the three-level laser module 1 , specifically, the second WDM 23 is connected to the first reflection unit 13 .

The three-level laser module 1 outputs the first pump light to the second WDM 23 , and the second WDM 23 outputs the first pump light to the second gain medium 22 . The second gain medium 22 absorbs the first pump light and radiates light of the third wavelength. The light of the third wavelength is bidirectionally output. Here, the “bidirectional output” points to the third reflection unit 21 to output the light of the third wavelength, and to The second WDM 23 outputs light of the third wavelength. After receiving the light of the third wavelength, the third reflection unit 21 reflects the light of the third wavelength, and inputs the light of the third wavelength into the second gain medium 22 again, thereby amplifying the light of the third wavelength again. The second WDM 23 outputs the light of the third wavelength to the output port of the dual-wavelength laser, and the light of the third wavelength can be used as a pump source of the relay amplifier.

In another example, in a dual-wavelength laser, the third reflection unit 21 in the four-level laser module 2 is located at an end far away from the three-level laser module 1, and the four-level laser module 2 uses a high-reflection device and a low-reflection device. The anti-device forms a resonant cavity to complete the screening of the light of the third wavelength. Figure 13 exemplarily provides a schematic structural diagram of the dual-wavelength laser. Referring to FIG. 13 , the four-level laser module 2 includes a third reflection unit 21 , a second gain medium 22 , a second WDM 23 and a fourth reflection unit 24 . The second WDM23 is a three-port device, see the description below. The second gain medium 22 is located between the third reflection unit 21 and the second WDM 23 . The second WDM 23 is connected to the three-level laser module 1 , specifically the second WDM 23 is connected to the first reflection unit 13 , and the second WDM 23 is located between the second gain medium 22 and the fourth reflection unit 24 .

Corresponding to the light of the third wavelength, the third reflective unit 21 is a high-reflective device, and the fourth reflective unit 24 is a low-reflective device. The three-level laser module 1 outputs the first pump light to the second WDM 23 , and the second WDM 23 outputs the first pump light to the second gain medium 22 . The second gain medium 22 absorbs the first pump light and radiates light of the third wavelength. The light of the third wavelength is bidirectionally output. Here, the “bidirectional output” points to the third reflection unit 21 to output the light of the third wavelength, and to The second WDM 23 outputs light of the third wavelength. After receiving the light of the third wavelength, the third reflection unit 21 reflects the light of the third wavelength, and inputs the light of the third wavelength into the second gain medium 22 again, thereby amplifying the light of the third wavelength again. The second WDM 23 outputs the light of the third wavelength to the fourth reflection unit 24 , the fourth reflection unit 24 reflects a small portion of the light of the third wavelength, and the small portion of the light of the third wavelength is input to the second gain medium through the second WDM 23 22. The fourth reflection unit 24, the second gain medium 22 and the third reflection unit 21 form a resonant cavity. The resonant cavity allows the light of the third wavelength to travel back and forth multiple times, which not only makes the dual-wavelength laser output the power of the light of the third wavelength. High, and the accurate third wavelength of light is selected. The third wavelength of light can be used as a pump source for the relay amplifier.

In another example, in the dual-wavelength laser shown in FIG. 12 , the four-level laser module 2 can also be directly provided with the pump light of the fourth wavelength, and the unused second pump light in the pump light can be directly provided. The pumped light is sent to the three-level laser module 1 for use, see Figure 14.

Specifically, see the dual-wavelength laser shown in Figure 15. The dual-wavelength laser also includes a second pump source 4. Four-level excitement The optical module 2 includes a third reflective unit 21, a second gain medium 22 and a second WDM 23. The second gain medium 22 is located between the third reflection unit 21 and the second WDM 23 . The second WDM 23 is connected to the three-level laser module 1 , specifically, the second WDM 23 is connected to the first reflection unit 13 . The second WDM 23 is also connected to the second pump source 4 . The third reflection unit 21 is also connected to the three-level laser module 1 , specifically, the third reflection unit 21 is also connected to the first WDM 12 .

The first reflection unit 13 in the three-level laser module 1 outputs the first pump light to the second WDM 23. The second pump source 4 may output pump light of a fourth wavelength, and the fourth wavelength may be the same as the first wavelength, or may be different from the first wavelength. The second pump source 4 outputs the pump light of the fourth wavelength to the second WDM 23 . The second gain medium 22 absorbs the first pump light and the pump light of the fourth wavelength, and radiates light of the third wavelength. The light of the third wavelength is output bidirectionally. The light of the third wavelength will be incident on the third reflection unit 21 and the second WDM 23. After receiving the light of the third wavelength, the third reflection unit 21 reflects the light of the third wavelength and inputs the light of the third wavelength into the second gain again. The medium 22 realizes the re-amplification of the light of the third wavelength. The second WDM 23 also outputs a third wavelength of light as the third wavelength of light output by the dual wavelength laser.

Due to the pump conversion efficiency of the pump light, it is impossible to 100% convert it into the required laser light. Therefore, the second gain medium 22 can transmit the unused second pump light in the fourth wavelength pump light to the third reflection. Unit 21. The third reflection unit 21 transmits the second pump light to the first WDM 12, and the first WDM 12 inputs the second pump light to the first gain medium 11. The first gain medium 11 can also absorb the second pump light and radiate the second pump light. Two wavelengths of light.

In the dual-wavelength laser shown in Figure 15, since there is also a second pump source 4, the restriction on the power of the pump light can be relaxed, the power of the pump light can be increased as much as possible, and a higher power laser can be obtained. output, and can prevent high-power pump light from being completely absorbed within a short distance, improving pump light utilization.

Moreover, by adjusting the power of the first pump source 3 and the second pump source 4, the two wavelengths of light output by the dual-wavelength laser can be freely adjusted within a certain range.

In another example, in a dual-wavelength laser, a resonant cavity is formed by a high-reflection device and a low-reflection device in the four-level laser module 2 to complete wavelength screening. In the dual-wavelength laser shown in Figure 15, the four-level laser module 2 also includes a fourth reflection unit 24. Referring to the dual-wavelength laser shown in Figure 16, the four-level laser module 2 includes a third reflection unit 21, a second reflection unit 24, and a second reflection unit 24. Gain medium 22 and fourth reflective unit 24 . Corresponding to the light of the third wavelength, the third reflective unit 21 is a high-reflective device, and the fourth reflective unit 24 is a low-reflective device. The second gain medium 22 is located between the third reflection unit 21 and the second WDM 23 . The third reflection unit 21 is connected to the first WDM 12 , the first reflection unit 13 is connected to the second WDM 23 , the second WDM 23 is connected to the fourth reflection unit 24 , and the second gain medium 22 is located between the second WDM 23 and the third reflection unit 21 .

The fourth reflective unit 24, the third reflective unit 21 and the second gain medium 22 form a resonant cavity. The resonant cavity allows the light of the third wavelength to travel back and forth multiple times, which not only makes the dual-wavelength laser output the light of the third wavelength relatively high, but also And select the accurate third wavelength of light.

In the dual-wavelength laser shown in Figures 15 and 16, there is a second pump source 4, which can make the power of the pump light used by the four-level laser module 2 relatively high, so that the power of the light of the third wavelength is relatively high. high.

In the dual-wavelength laser shown in FIG. 15 and FIG. 16 , the three-level laser module 1 may or may not include the second reflection unit 14 .

In another example, in the dual-wavelength laser shown in Figures 15 and 16, in order to prevent the light of the second wavelength and the light of the third wavelength from affecting each other, the three-level laser module 1 and the four-level laser module 1 can be An isolation module is provided between the laser modules 2. Specifically, the dual-wavelength laser also includes a second isolation module 6 and a third isolation module 7. See the dual-wavelength laser shown in Figure 17.

The second isolation module 6 is located between the second WDM 23 and the three-level laser module 1 . The second isolation module 6 enables The pump light of the first wavelength and the pump light of the fourth wavelength pass, and the light of the second wavelength and the light of the third wavelength are blocked from passing.

The third isolation module 7 is located between the three-level laser module 1 and the third reflection unit 21 . The third isolation module 7 can allow the pump light of the first wavelength and the pump light of the fourth wavelength to pass through, and prevent the light of the second wavelength and the light of the third wavelength from passing through.

In the dual-wavelength laser shown in Figure 17, the light of the second wavelength will not be input to the four-level laser module 2, and the light of the third wavelength will not be input to the three-energy laser module 1, so the three-level laser module 1 can be made It will not interact with the four-level laser module 2.

In an example, the second isolation module 6 and the third isolation module 7 may be the filters mentioned above, etc.

In another example, the second isolation module 6 and the third isolation module 7 can be the isolators mentioned above. The second isolation module 6 cannot prevent the light of the second wavelength from entering the four-level laser module 2. The isolation module 7 cannot prevent the light of the third wavelength from entering the three-level laser module 1 .

In an example, in the dual-wavelength laser shown in FIG. 15 , the third reflection unit 21 can also output the unused pump light of the first pump light to the three-level laser module 1 . Specifically, the third reflection unit 21 outputs the unused pump light to the first WDM 12 . The first WDM 12 outputs the unused pump light to the first gain medium 11. The first gain medium 11 can also absorb the unused pump light and radiate light of the second wavelength. In this way, the pump light of the first wavelength can be recycled and the conversion efficiency of the pump light can be improved.

In one example, the pump light of the fourth wavelength is multi-mode pump light.

In one example, the second gain medium 22 can be an optical fiber doped with ytterbium ions, and can be connected with 6/125DCF low loss to realize the connection between the single-mode signal in the fiber core and the multi-mode signal in the inner cladding. Low-loss connection, multi-mode signal refers to the pump optical signal.

In one example, the third WDM 23 may be a three-port device, specifically a three-port optical fiber combiner for pump light and signal light, which includes a pump light input port, a signal light transmission port, and A common transmission port for signal light and pump light. When the third WDM 23 is a three-port device, it means that there is one pump source, that is to say, the second pump source 4 outputs one pump light to the four-level laser module 2 . For example, the second pump source 4 is a 915 nm multi-mode pump laser, or a 975 nm multi-mode pump laser.

In another example, the third WDM 23 can also be a four-port device, specifically a (2+1)x1 pump light/signal fiber combiner, which includes two pump light input ports and one signal light transmission port and a common transmission port for signal light and pump light. When the third WDM23 is a four-port device, it means that there are two pump sources. That is to say, the second pump source 4 outputs two pump lights to the four-level laser module 2. The two pump lights form the components described above. The pump light of the fourth wavelength, the wavelength of the two pump lights is the fourth wavelength, and the power of the two pump lights may be equal or unequal. For example, the second pump source 4 includes a third pump unit 41 and a fourth pump unit 42. Both the third pump unit 41 and the fourth pump unit 42 are 915 nm multi-mode pump lasers. Both the pump unit 41 and the fourth pump unit 42 are connected to the second WDM 23, or the second pump source 4 includes a third pump unit 41 and a fourth pump unit 42, and the third pump unit 41 and the fourth pump unit 42 are connected to the second WDM 23. The pump units 42 are both 975nm multi-mode pump lasers. The third pump unit 41 and the fourth pump unit 42 are both connected to the second WDM 23. See the dual-wavelength laser shown in Figure 18.

In the port of the third WDM23, the pump light input port can be a 105/125 μm, NA=0.22 multi-mode optical fiber. “105” indicates that the core diameter is 105 μm, and “125” indicates that the cladding diameter of the optical fiber is 125 μm. The signal light transmission port can be 6/125μm DCF, and the common transmission port for signal light and pump light can be 20/125 DCF. "6" means the core diameter is 6μm, "125" means the outer cladding diameter of the fiber is 125μm, and the typical inner cladding diameter is 105μm. "20" means the core diameter is 20μm.

It should be noted that in the dual-wavelength lasers shown in Figures 15 to 17, the first WDM12 is a four-port device, and the first pump source 3 only provides one channel of pump light of the first wavelength, and the second WDM23 is a four-port device. port device, and the second pump source 4 only provides one pump light of the fourth wavelength. When the first pump source 3 provides two channels of pump light with the first wavelength, the first WDM 12 is a five-port device. When the second pump source 4 provides two channels of pump light with the fourth wavelength, the second WDM 23 is a five-port device.

In one example, the third reflective unit 21 is a reflective FBG, and is a high reflectivity FBG. The third reflection unit 21 may be obtained by writing in a single-mode optical fiber, and the embodiment of the present application does not limit the type of single-mode optical fiber.

The fourth reflective unit 24 is also a reflective FBG, and is a low reflectivity FBG. The fourth reflective unit 24 can be obtained by writing in DCF.

In the dual-wavelength laser shown in FIGS. 7 to 17 , the specific structure of the three-level laser module 1 can be the structure of the three-level laser module 1 shown in FIG. 5 or 6 .

In the embodiment of this application, compared with the 915nm pump light, the theoretical quantum efficiency of the three-level laser module 1 is relatively higher, which is 99%, and the theoretical quantum efficiency of the four-level laser module 2 is relatively high. is 92%, which effectively improves the utilization rate of the pump light, so the lengths of the first gain medium 11 and the second gain medium 22 can be further reduced. In addition, the pump light output by the first pump source 3 and the second pump source 4 also contains pump light that is not used by the dual-wavelength laser. This part of the pump light can be directly used for the post-amplification of the L-band. The pump light can be further fully utilized and the utilization rate of the pump light can be improved.

In the embodiment of the present application, by arranging the three-level laser module 1 and the four-level laser module 2 in cascade, the pump light of the first wavelength is converted into the light of the second wavelength and the light of the third wavelength, and the third wavelength can be fully utilized. Pump light of one wavelength improves the utilization rate of pump light.

In the embodiment of the present application, a relay amplifier is also provided. See the relay amplifier shown in Figure 19. The relay amplifier includes a third WDM01, a third gain medium 02, a fourth WDM03, a fourth gain medium 04 and The dual-wavelength laser described previously.

The third WDM01 couples the light of the second wavelength to the third gain medium 02. The third gain medium 02 absorbs the light of the second wavelength and amplifies the signal light of the first wavelength band that passes through the relay amplifier. The fourth WDM03 couples the light of the third wavelength to the fourth gain medium 04. The fourth gain medium 04 absorbs the light of the third wavelength and amplifies the signal light of the second wavelength band that passes through the relay amplifier.

For example, the second wavelength is 980nm, the first waveband is C-band, the third wavelength is 1050nm, and the second waveband is S-band.

In the embodiment of the present application, another relay amplifier is also provided. See the relay amplifier shown in Figure 20. The relay amplifier includes a third WDM01, a third gain medium 02, a fourth WDM03, and a fourth gain medium 04. , power splitter 05, fifth WDM06 and fifth gain medium 07 and the dual-wavelength laser described above.

The light of the second wavelength is input to the power splitter 05 and is divided into two beams. The third WDM01 couples a beam of light of the second wavelength to the third gain medium 02. The third gain medium 02 absorbs the light of the second wavelength. The signal light of the first band that passes through the relay amplifier is amplified. The fifth WDM06 couples a beam of light of the second wavelength to the fifth gain medium 07. The fifth gain medium 07 absorbs the light of the second wavelength and amplifies the signal light of the third waveband that passes through the relay amplifier.

The fourth WDM03 couples the light of the third wavelength to the fourth gain medium 04. The fourth gain medium 04 absorbs the light of the third wavelength and amplifies the signal light of the second wavelength band that passes through the relay amplifier.

For example, the second wavelength is 980nm, the first waveband is C-band, the third waveband is L-band, and the third wavelength is 1050nm, The second band is S-band.

In the embodiment of the present application, another relay amplifier is also provided. See the relay amplifier shown in Figure 21. The relay amplifier includes a third WDM01, a third gain medium 02, a fourth WDM03, and a fourth gain medium 04. , power splitter 05, fifth WDM06, fifth gain medium 07, sixth WDM08, seventh WDM09 and the dual-wavelength laser described above.

The signal light includes the signal light of the first wave band, the second wave band and the third wave band. The signal light is input to the sixth WDM08 of the relay amplifier. The sixth WDM08 separates the signal light of the first band, the signal light of the second band and the signal light of the third band, and then inputs them into the third WDM01 and the fifth WDM06 respectively. and fourth WDM03.

The light of the second wavelength is input to the power splitter 05 and is divided into two beams. The third WDM01 couples a beam of light of the second wavelength to the third gain medium 02. The third gain medium 02 absorbs the light of the second wavelength. The signal light of the first waveband passing through the third gain medium 02 is amplified. The fifth WDM06 couples a beam of light of the second wavelength to the fifth gain medium 07 . The fifth gain medium 07 absorbs the light of the second wavelength and amplifies the signal light of the third wavelength band that passes through the fifth gain medium 07 . After the light of the second wavelength is split into two beams by the power splitter 05, the powers are respectively the first power and the second power. The magnitudes of the first power and the second power can be set according to actual needs.

The fourth WDM03 couples the light of the third wavelength to the fourth gain medium 04 , and the fourth gain medium 04 absorbs the light of the third wavelength and amplifies the signal light of the second wavelength band that passes through the fourth gain medium 04 .

The seventh WDM09 combines the amplified signal light of the first band, the signal light of the second band and the signal light of the third band into one signal light, which is output from the relay amplifier.

For example, the second wavelength is 974nm, the first waveband is C-band, the third waveband is L-band, the third wavelength is 1050nm, and the second waveband is S-band.

In the embodiment of the present application, another relay amplifier is also provided. See the relay amplifier shown in Figure 22. The relay amplifier shown in Figure 22 is similar to the relay amplifier shown in Figure 21. The difference lies in: power splitting Device 05 divides the light of the second wavelength into three beams. The powers of the three beams are respectively the third power, the fourth power and the fifth power. The sizes of the third power, the fourth power and the fifth power can be set according to actual needs. , two of the three beams of light have the same purpose as the relay amplifier described in Figure 21. The other beam is input to the fourth WDM03 and coupled to the fourth gain medium 04 through the fourth WDM03. The fourth gain medium 04 absorbs the third The light of the wavelength and the light of the second wavelength amplify the signal light of the second wavelength band that passes through the fourth gain medium 04 .

In this application, the terms "first" and "second" are used to distinguish identical or similar items with substantially the same functions and functions. It should be understood that there is no logical or logical connection between "first" and "second". Timing dependencies do not limit the number and execution order. It should also be understood that, although the following description uses the terms first, second, etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another. For example, a first pump source may be referred to as a second pump source, and similarly, a second pump source may be referred to as a first pump source, without departing from the scope of various examples. Both the first pump source and the second pump source may be pump sources, and in some cases, may be separate and different pump sources.

The term "at least one" in this application means one or more, and the term "plurality" in this application means two or more.

The above description is only an exemplary implementation of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of various equivalents within the technical scope disclosed in the present application. modifications or substitutions, these modifications or substitutions shall be covered by the protection scope of this application. Therefore, the protection scope of this application should be determined by the claims The scope of protection shall prevail.

Claims (16)

1. A dual-wavelength laser, characterized by including a three-level laser module (1), a four-level laser module (2) and a first pump source (3);

   The gain medium of the three-level laser module (1) is an optical fiber doped with at least ytterbium ions, and the gain medium of the four-level laser module (2) is an optical fiber doped with at least ytterbium ions;

   The first pump source (3) is used to output pump light of a first wavelength to the three-level laser module (1);

   The three-level laser module (1) is used to absorb the pump light of the first wavelength, radiate the light of the second wavelength, and output the first wavelength to the four-level laser module (2). The unused first pump light among the pump lights;

   The four-level laser module (2) is used to absorb the first pump light and radiate light of a third wavelength.
2. The dual-wavelength laser according to claim 1, characterized in that the three-level laser module (1) includes a first gain medium (11), a first wavelength division multiplexer WDM (12) and a first reflection unit (13), the first gain medium (11) is located between the first WDM (12) and the first reflection unit (13);

   The first WDM (12) is used to output the pump light of the first wavelength to the first gain medium (11);

   The first gain medium (11) is used to absorb the pump light of the first wavelength, bidirectionally output the light of the second wavelength, and output the first wavelength to the first reflection unit (13). The unused first pump light among the pump lights;

   The first reflection unit (13) is used to reflect and output the light of the second wavelength to the first gain medium (11), and transmit the first pump light to the four-level laser module (2 );

   The first WDM (12) is also used to output the light of the second wavelength output by the first gain medium (11).
3. The dual-wavelength laser according to claim 2, characterized in that the three-level laser module (1) further includes a second reflection unit (14), the second reflection unit (14) responds to the second wavelength The reflectivity of the light of the second reflection unit (13) is lower than the reflectance of the first reflection unit (13) for the light of the second wavelength, and the transmittance of the second reflection unit (14) for the light of the second wavelength is higher than Reflectivity to light of the second wavelength;

   The first WDM (12) is located between the first gain medium (11) and the second reflective unit (14);

   The first WDM (12) is also used to output the light of the second wavelength to the second reflection unit (14);

   The second reflection unit (14) is used to form a resonant cavity with the first gain medium (11) and the first reflection unit (13) for selecting the light of the second wavelength.
4. The dual-wavelength laser according to any one of claims 1 to 3, characterized in that the four-level laser module (2) includes a third reflection unit (21) and a second gain medium (22);

   The third reflection unit (21) is used to transmit and output the first pump light output by the three-level laser module (1) to the second gain medium (22);

   The second gain medium (22) is used to absorb the first pump light and bidirectionally output the light of the third wavelength;

   The third reflection unit (21) is also used to reflect the light of the third wavelength.
5. The dual-wavelength laser according to claim 4, wherein the dual-wavelength laser further includes a second pump Pu source (4), the four-level laser module (2) also includes a second WDM (23);

   The second gain medium (22) is located between the third reflective unit (21) and the second WDM (23);

   The second pump source (4) is used to output pump light of a fourth wavelength to the second WDM (23);

   The second WDM (23) is configured to output the pump light of the fourth wavelength to the second gain medium (22);

   The second gain medium (22) is used to absorb the first pump light and the pump light of the fourth wavelength, and bidirectionally output the light of the third wavelength;

   The second WDM (23) is also used to output the light of the third wavelength output by the second gain medium (22).
6. The dual-wavelength laser according to any one of claims 1 to 3, characterized in that the four-level laser module (2) includes a third reflection unit (21), a second gain medium (22) and a second WDM (twenty three);

   The second gain medium (22) is located between the third reflective unit (21) and the second WDM (23);

   The second WDM (23) is used to output the first pump light output by the three-level laser module (1) to the second gain medium (22);

   The second gain medium (22) is used to absorb the first pump light and bidirectionally output light of the third wavelength;

   The third reflection unit (21) is used to reflect the light of the third wavelength;

   The second WDM (23) is also used to output the light of the third wavelength output by the second gain medium (22).
7. The dual-wavelength laser according to any one of claims 1 to 6, characterized in that the dual-wavelength laser further includes a first isolation module (5);

   The first isolation module (5) is located between the three-level laser module (1) and the four-level laser module (2);

   The first isolation module (5) is used to allow the pump light of the first wavelength to pass through and prevent the light generated by the four-level laser module (2) from passing through.
8. The dual-wavelength laser according to claim 6, characterized in that the dual-wavelength laser includes a second pump source (4);

   The second pump source (4) is used to output pump light of a fourth wavelength to the second WDM (23);

   The second gain medium (22) is used to absorb the first pump light and the pump light of the fourth wavelength, bidirectionally output the light of the third wavelength, and transmit the light to the third reflection unit ( 21) Output the unused second pump light among the pump lights of the fourth wavelength;

   The third reflection unit (21) is also used to output the second pump light to the three-level laser module (1).
9. The dual-wavelength laser according to claim 8, characterized in that the dual-wavelength laser further includes a second isolation module (6) and a third isolation module (7);

   The second isolation module (6) is located between the second WDM (23) and the three-level laser module (1). The second isolation module (6) is used to make the first wavelength The pump light and the pump light of the fourth wavelength pass through, and the light generated by the three-level laser module (1) and the light generated by the four-level laser module (2) are prevented from passing;

   The third isolation module (7) is located between the three-level laser module (1) and the third reflection unit (21). The third isolation module (7) is used to make the first The pump light of the wavelength and the pump light of the fourth wavelength pass through, and the light generated by the three-level laser module (1) and the light generated by the four-level laser module (2) are prevented from passing through.
10. The dual-wavelength laser according to any one of claims 4 to 6 and 8 to 9, characterized in that the four-level laser module (2) further includes a fourth reflection unit (24), and the fourth reflection unit (24) The reflectivity of the unit (24) to the light of the third wavelength is lower than the reflectivity of the third reflection unit (21) to the light of the third wavelength, and the fourth reflection unit (24) has a reflectivity of the light of the third wavelength. The transmittance of the light of the third wavelength is higher than the reflectance of the light of the third wavelength;

    The second WDM (23) is located between the second gain medium (22) and the fourth reflective unit (24);

    The fourth reflection unit (24) is used to form a resonant cavity with the third reflection unit (21) and the second gain medium (22) for selecting the light of the third wavelength.
11. The dual-wavelength laser according to any one of claims 1 to 10, characterized in that the pump light of the first wavelength is multi-mode pump light.
12. The dual-wavelength laser according to claim 5 or 8, characterized in that the pump light of the fourth wavelength is multi-mode pump light.
13. The dual-wavelength laser according to any one of claims 1 to 12, wherein the first wavelength is 915 nm or 975 nm, the second wavelength ranges from 970 nm to 980 nm, and the third wavelength range is 1030nm～1100nm.
14. The dual-wavelength laser according to claim 2 or 3, characterized in that both the first reflection unit (13) and the second reflection unit (14) are reflective fiber Bragg gratings.
15. The dual-wavelength laser according to claim 10, characterized in that both the third reflection unit (23) and the fourth reflection unit (24) are reflective fiber Bragg gratings.
16. A relay amplifier, characterized in that it includes a third wavelength division multiplexer WDM, a third gain medium, a fourth WDM, a fourth gain medium and a dual-wavelength laser as claimed in any one of claims 1 to 15;

    The third WDM is used to couple the light of the second wavelength to the third gain medium;

    The third gain medium is used to absorb the light of the second wavelength and amplify the signal light of the first waveband passing through the relay amplifier;

    The fourth WDM is used to couple light of a third wavelength to a fourth gain medium;

    The fourth gain medium is used to absorb the light of the third wavelength and amplify the signal light of the second waveband passing through the relay amplifier.