Multimode laser, pump laser, optical amplifier and communication system
By integrating a multimode laser design, the problem of limited output power of single-mode pump lasers was solved, achieving a compact structure and increased power, and enhancing the communication performance of the optical amplifier.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUAWEI TECH CO LTD
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
Smart Images
Figure CN122118511A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optoelectronic communication, and in particular to multimode lasers, pump lasers, optical amplifiers and communication systems. Background Technology
[0002] An optical amplifier is an electronic device used in communication systems to amplify signal light.
[0003] Among related technologies, an erbium-doped fiber amplifier (EDBFA) has been widely used due to its excellent performance and mature technology, becoming a preferred choice in optical repeater amplification technology. This optical amplifier offers two selectable pump bands: 980nm and 1480nm. The 980nm pump, used in a three-level system, achieves a high population inversion rate, resulting in excellent noise figure performance and thus widespread adoption. This optical amplifier includes a pump laser, which provides pump light energy to the amplifier. The use of a 980nm single-mode pump laser enables low noise figure and high power conversion efficiency, making the 980nm single-mode pump laser the mainstream pump laser.
[0004] However, in related technologies, single-mode pump lasers maintain single-mode output, and the chip's structure and size limit the pump laser's output power to around 1W. This restricts the maximum pump power that can be coupled into the final stage of the optical amplifier's amplification erbium fiber, thus limiting the maximum output power of the optical amplifier. Summary of the Invention
[0005] This application provides a multimode laser, a pump laser, an optical amplifier, and a communication system to solve the problem of limited maximum output power of optical amplifiers. The technical solution is as follows:
[0006] In a first aspect, a multimode laser is provided, comprising a housing, a laser unit, a first collimating component, a wavelength selective reflection component, a second collimating component, and an output pigtail. The laser unit, the first collimating component, the wavelength selective reflection component, the second collimating component, and the output pigtail are all located within the housing, thereby effectively ensuring the integration of the multimode laser and making its structure compact. The laser unit outputs pump light of a first wavelength, which can propagate along a first path or a second path. When the pump light propagates along the first path, it sequentially passes through the first collimating component, the wavelength selective reflection component, the second collimating component, and the inner cladding of the output pigtail. During the propagation of the pump light, it is collimated by the first collimating component, then transmitted through the wavelength selective reflection component, then focused by the second collimating component, and finally coupled into the inner cladding of the output pigtail. When the pump light propagates along the second path, it sequentially passes through the first collimating component, the second collimating component, the wavelength selective reflection component, and the inner cladding of the output pigtail. During the propagation of the pump light, it is collimated by the first collimating component, then focused by the second collimating component, then transmitted through the wavelength selective reflection component, and finally coupled into the inner cladding of the output pigtail. That is, the pump light can propagate to the inner cladding of the output pigtail along either the first path or the second path. Additionally, the wavelength selective reflection component also reflects a second wavelength signal light output from the core of the output pigtail, the second wavelength being greater than the first wavelength, and this signal light is generated by the pump light gain.
[0007] The multimode laser provided in this application embodiment has at least the following effects:
[0008] The laser unit, the first collimation component, the wavelength selective reflection component, the second collimation component, and the output pigtail of the multimode laser are all integrated into the housing of the multimode laser, thereby effectively ensuring the integration of the multimode laser, making the structure of the multimode laser compact, and thus reducing the number of components in the pump laser configured with the multimode laser.
[0009] In one implementation of this application, when the pump light is transmitted along the first path, the wavelength-selective reflection component and the second collimation component are an integral structural component.
[0010] This design, which assembles the wavelength selective reflection component and the second collimation component into a whole, can improve the structural compactness of the multimode laser. On the other hand, after assembling the wavelength selective reflection component and the second collimation component into a whole, it is only necessary to couple it with the first collimation component and the fiber core of the output pigtail, which effectively reduces the assembly difficulty and improves the assembly efficiency.
[0011] In one implementation of this application, the wavelength selective reflection component includes a first volume Bragg grating. The first volume Bragg grating is located between the first collimating component and the second collimating component. On one hand, the first volume Bragg grating can transmit the collimated pump light output from the first collimating component to the second collimating component. On the other hand, the signal light output in reverse from the core of the output pigtail is focused by the second collimating component and transmitted to the first volume Bragg grating, and then reflected back to the second collimating component. The second collimating component further couples the collimated signal light back to the core of the output pigtail.
[0012] This design allows for the transmission of the pump light and the reflection of the signal light solely through the first body Bragg grating, which improves the integration of the multimode laser and makes its structure more compact.
[0013] In one implementation of this application, the wavelength-selective reflection component includes a dichroic mirror and a first reflector. The combination of the dichroic mirror and the first reflector achieves the same effect as the first volume Bragg grating, namely, transmitting the pump light and reflecting the signal light. The dichroic mirror is located between the first collimating component and the second collimating component. On one hand, the dichroic mirror transmits the collimated pump light output from the first collimating component to the second collimating component. On the other hand, the signal light output from the core of the output pigtail is focused by the second collimating component and transmitted to the dichroic mirror, and then reflected back to the first reflector. The first reflector then reflects the optical signal back to the second collimating component, which further couples the collimated signal light back to the core of the output pigtail.
[0014] Although this design increases the number of components compared to a wavelength selective reflection assembly that only includes the first volume Bragg grating, it effectively reduces manufacturing difficulty and cost.
[0015] In one implementation of this application, when the pump light is transmitted along the second path, the wavelength selective reflective component is located at the end of the core of the output pigtail.
[0016] This design, by directly placing the wavelength selective reflection component at the end of the output fiber core, effectively simplifies the structure of the wavelength selective reflection component and improves the structural compactness of the multimode laser. Furthermore, the assembly process for the wavelength selective reflection component is omitted during the assembly of the multimode laser, effectively reducing assembly difficulty.
[0017] In one implementation of this application, the wavelength selective reflection component includes a dielectric film. The dielectric film is located at the end of the output pigtail. The dielectric film can transmit the collimated pump light output from the second collimation component to the inner cladding of the output pigtail, and can also reflect the signal light output from the core of the output pigtail back to the core of the output pigtail.
[0018] This design allows for the transmission of the pump light and the reflection of the signal light solely through the dielectric film, which improves the integration of the multimode laser and makes its structure more compact.
[0019] In one implementation of this application, there are multiple laser units arranged sequentially. Each first collimating component corresponds to one of the laser units, and the arrangement direction of each first collimating component is consistent with the arrangement direction of each laser unit. In this way, the pump light output from each laser unit can be transmitted to the corresponding first collimating component and thus collimated by it. Furthermore, the multimode laser also includes second mirrors, each corresponding to one of the first collimating components, and the arrangement direction of each second mirror is consistent with the arrangement direction of each first collimating component.
[0020] In this way, each of the second reflectors can combine the collimated pump light output from each of the first collimating components into a single beam, thus completing the spatial beam combining of the pump light. The pump light after spatial beam combining will couple to the wavelength-selective reflector if it propagates along the first path, and to the second collimating component if it propagates along the second path.
[0021] Secondly, a pump laser is provided, comprising a multimode laser, a gain fiber, and a partial optical reflector. The multimode laser is the same as described in the first aspect. One end of the gain fiber is connected to the output pigtail, such that the core of the gain fiber is connected to the core of the output pigtail, and the inner cladding of the gain fiber is connected to the inner cladding of the output pigtail. In this way, the pump light of the first wavelength in the inner cladding of the output pigtail can be transmitted to the inner cladding of the gain fiber, resulting in a significant gain in the core of the gain fiber and generating a signal light of the second wavelength. Furthermore, since the partial optical reflector is connected to the other end of the gain fiber, it can transmit the first portion of the signal light and reflect the second portion of the signal light. Therefore, the first portion of the signal light is output normally, while the second portion of the signal light is output in the reverse direction along the core of the gain fiber to the wavelength selective reflection component, and resonance occurs between the partial optical reflector and the wavelength selective reflection component, thereby generating quasi-single-mode stimulated emission of the second wavelength.
[0022] The pump laser provided in this application embodiment has at least the following effects:
[0023] The system includes a multimode laser as described in the first aspect, which has a compact structure and a large maximum output power, thus facilitating the improvement of the maximum output power of the pump laser. The gain fiber includes a core and an inner cladding. The pump light of the first wavelength output by the multimode laser propagates through the inner cladding of the gain fiber, resulting in a significant gain in the core of the gain fiber and generating a signal light of the second wavelength. Furthermore, under the action of the partial optical reflector, the signal light in the core of the gain fiber resonates between the partial optical reflector and the wavelength selective reflection component, thereby generating quasi-single-mode stimulated emission of the second wavelength.
[0024] In one implementation of this application, when the first wavelength is 930nm to 950nm and the second wavelength is 972nm to 982nm, the core of the gain fiber is made of germanium-doped silica glass, the inner cladding of the gain fiber is made of germanium-doped silica glass, and the refractive index of the core of the gain fiber is higher than the refractive index of the inner cladding of the gain fiber.
[0025] The design of the core and cladding material of the gain fiber in this way enables a significant gain to be generated in the core of the gain fiber and to generate signal light of the second wavelength.
[0026] In one implementation of this application, the core of the gain fiber has a radius of 5 μm to 10 μm and a numerical aperture greater than 0.05. The inner cladding of the gain fiber has a radius of 17 μm to 30 μm and a numerical aperture greater than 0.38.
[0027] By designing the parameters of the core and inner cladding of the gain fiber in this way, the overall conversion efficiency of the gain fiber can be effectively improved.
[0028] In one implementation of this application, when the first wavelength is 905nm to 925nm and the second wavelength is 972nm to 982nm, the core material of the gain fiber is ytterbium-doped silica glass and the inner cladding material of the gain fiber is germanium-doped silica glass.
[0029] The design of the core and cladding material of the gain fiber in this way enables a significant gain to be generated in the core of the gain fiber and to generate signal light of the second wavelength.
[0030] In one implementation of this application, the core of the gain fiber has a radius of 5 μm to 10 μm and a numerical aperture greater than 0.05. The inner cladding of the gain fiber has a radius of 17 μm to 30 μm and a numerical aperture greater than 0.45.
[0031] By designing the parameters of the core and inner cladding of the gain fiber in this way, the overall conversion efficiency of the gain fiber can be effectively improved.
[0032] Thirdly, an optical amplifier is provided, the optical amplifier comprising the pump laser described in the second aspect.
[0033] The optical amplifier provided in this application embodiment has at least the following effects:
[0034] The system includes the pump laser described in the second aspect, which has a compact structure and a large maximum output power, thus contributing to the improvement of the maximum output power of the optical amplifier.
[0035] Fourthly, a communication system is provided, the communication system comprising the optical amplifier described in the third aspect.
[0036] The communication system provided in this application embodiment has at least the following effects:
[0037] The optical amplifier described in the third aspect has a large maximum output power, which is beneficial to improving the communication capacity and communication distance of the communication system. Attached Figure Description
[0038] Figure 1 A frame diagram of a multimode laser provided in an embodiment of this application;
[0039] Figure 2 A frame diagram of a multimode laser provided in an embodiment of this application;
[0040] Figure 3 This is a schematic diagram of the structure of a multimode laser provided in an embodiment of this application;
[0041] Figure 4 This is a schematic diagram of the structure of a multimode laser provided in an embodiment of this application;
[0042] Figure 5 This is a schematic diagram of the structure of a multimode laser provided in an embodiment of this application;
[0043] Figure 6 This is a schematic diagram of the structure of a multimode laser provided in an embodiment of this application;
[0044] Figure 7 A frame diagram of a pump laser provided in an embodiment of this application;
[0045] Figure 8 A cross-sectional view of the gain fiber provided in an embodiment of this application;
[0046] Figure 9 This is a schematic diagram of the structure of an optical amplifier provided in an embodiment of this application;
[0047] Figure 10 This is a schematic diagram of another optical amplifier provided in an embodiment of this application;
[0048] Figure 11 This is a schematic diagram of the structure of another optical amplifier provided in an embodiment of this application.
[0049] Legend:
[0050] 10. Shell;
[0051] 20. Laser unit;
[0052] 30. First collimation component;
[0053] 310. Fast-axis collimating lens;
[0054] 320. Slow-axis collimating lens;
[0055] 330. Second-body Bragg grating;
[0056] 40. Wavelength-selective reflection component;
[0057] 410. First-body Bragg grating;
[0058] 420. Dimorphic mirror;
[0059] 430. First reflecting mirror;
[0060] 440. Dielectric membrane;
[0061] 50. Second collimation component;
[0062] 60. Output fiber optic pigtail;
[0063] 70. Second reflecting mirror;
[0064] 100. Multimode laser;
[0065] 200. Gain fiber;
[0066] 201. Core; 202. Inner cladding; 203. Outer cladding;
[0067] 300. Partial light reflector;
[0068] 11(12), First optical isolator; 21(22), Pump multiplexer; 31(32), Erbium-doped fiber; 41(42), Second optical isolator; 52, First band multiplexer / demultiplexer; 62, Second band multiplexer / demultiplexer.
[0069] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation
[0070] The terminology used in the implementation section of this application is for the purpose of explaining the embodiments of this application only, and is not intended to limit this application.
[0071] With the continuous technological advancements in optical fiber communication systems, the spectrum supported by dense wavelength division multiplexing (DWDM) systems has expanded from the early C-band 4THz to C-band 6THz. Currently, there is further development towards C-band 6THz + L-band 6THz, and the transmission fiber is evolving from G.652D standard single-mode fiber to G.654E ultra-large effective area ultra-low loss fiber. In the future, parallel amplification or high-power optical amplification combined with hollow fiber with low nonlinear characteristics may emerge to further improve communication capacity and distance.
[0072] The aforementioned evolution process is inseparable from the continuous improvement of the total output power of the optical amplifier in the communication system, which means that the pump laser in the optical amplifier needs to provide higher pump power.
[0073] Erbium-doped fiber amplifiers (EDFAs), with their excellent performance and mature technology, have been widely used and have become the preferred choice for optical repeater amplification technology. These amplifiers offer two selectable pump bands: 980nm and 1480nm. The 980nm pump, used in a three-level system, achieves a high population inversion rate, resulting in excellent noise figure performance and thus widespread adoption. In related technologies, this optical amplifier includes a pump laser, which provides pump light energy to the amplifier. The use of a 980nm single-mode pump laser enables low noise figure and high power conversion efficiency, making the 980nm single-mode pump laser the mainstream pump laser.
[0074] However, in related technologies, single-mode pump lasers maintain single-mode output, and the chip's structure and size limit the pump laser's output power to around 1W. This restricts the maximum pump power that can be coupled into the final stage of the optical amplifier's amplification erbium fiber, thus limiting the maximum output power of the optical amplifier.
[0075] To address the aforementioned technical problems, this application provides a multimode laser 100. Figure 1 For a frame diagram of the multimode laser 100, see [link / reference]. Figure 1 In this embodiment, the multimode laser 100 includes a housing 10, and a laser unit 20, a first collimation component 30, a wavelength selective reflection component 40, a second collimation component 50, and an output pigtail 60 located within the housing 10.
[0076] The laser unit 20 outputs pump light of a first wavelength, which can be transmitted along either a first path or a second path. The first path consists of a first collimation component 30, a wavelength selective reflection component 40, a second collimation component 50, and the inner cladding of the output pigtail 60. The second path also consists of the first collimation component 30, the second collimation component 50, the wavelength selective reflection component 40, and the inner cladding of the output pigtail 60. The wavelength selective reflection component 40 reflects the signal light of a second wavelength, which is longer than the first wavelength, output from the core of the output pigtail 60.
[0077] Since the laser unit 20, the first collimation component 30, the wavelength selective reflection component 40, the second collimation component 50 and the output pigtail 60 are all located inside the housing 10, the integration of the multimode laser 100 is effectively guaranteed, making the structure of the multimode laser 100 compact.
[0078] In this embodiment, the output pigtail 60 is a double-clad optical fiber, comprising a core, an inner cladding, and an outer cladding. The inner cladding wraps around the core, and the outer cladding wraps around the inner cladding. An acrylic coating is provided on the outer surface of the outer cladding to protect the output pigtail 60 and improve its reliability.
[0079] During the operation of the multimode laser 100, the laser unit 20 is used to output pump light of a first wavelength, which can travel along a first path (see...). Figure 1 ) or the second path (see Figure 2 )transmission.
[0080] In some examples, as the pump light propagates along the first path, it sequentially passes through the first collimating component 30, the wavelength-selective reflector 40, the second collimating component 50, and the inner cladding of the output pigtail 60. During the propagation of the pump light, it is collimated by the first collimating component 30, then transmitted through the wavelength-selective reflector 40, then collimated by the second collimating component 50, and finally coupled into the inner cladding of the output pigtail 60.
[0081] In other examples, as the pump light propagates along the second path, it sequentially passes through the first collimating component 30, the second collimating component 50, the wavelength-selective reflector 40, and the inner cladding of the output pigtail 60. During the propagation of the pump light, it is collimated by the first collimating component 30, then by the second collimating component 50, then transmitted through the wavelength-selective reflector 40, and finally coupled into the inner cladding of the output pigtail 60.
[0082] In other words, the pump light can be transmitted to the inner cladding of the output pigtail 60 along the first path or along the second path. Additionally, the wavelength-selective reflector 40 is also used to reflect a second wavelength signal light output from the core of the output pigtail 60. This second wavelength is longer than the first wavelength, and the signal light is generated by the pump light gain.
[0083] The multimode laser 100 provided in this application embodiment has at least the following effects:
[0084] The laser unit 20, the first collimation component 30, the wavelength selective reflection component 40, the second collimation component 50, and the output pigtail 60 of the multimode laser 100 are all integrated within the housing 10 of the multimode laser 100, thereby effectively ensuring the integration of the multimode laser 100, making the structure of the multimode laser 100 compact, and thus reducing the number of components in the pump laser configured with the multimode laser.
[0085] As mentioned above, there are two transmission paths for the pump light: the first path and the second path. The following sections will explain the pump light along the first and second paths, respectively.
[0086] Combination Figure 1 In this embodiment, when the pump light is transmitted along the first path, the wavelength selection reflection component 40 and the second collimation component 50 are integrated structural components.
[0087] In the above implementation, assembling the wavelength selective reflection component 40 and the second collimation component 50 into a whole can, on the one hand, improve the structural compactness of the multimode laser 100, and on the other hand, after assembling the wavelength selective reflection component 40 and the second collimation component 50 into a whole, it is only necessary to couple it with the fiber core of the first collimation component 30 and the output pigtail 60, which effectively reduces the assembly difficulty.
[0088] Figure 3 This is a schematic diagram of the structure of a multimode laser 100. In some examples, the wavelength selective reflective component 40 includes a dichroic mirror 420 and a first reflector 430.
[0089] A dichroic mirror 420 is located between the first collimating component 30 and the second collimating component 50. The dichroic mirror 420 transmits pump light to the second collimating component 50 and reflects signal light to the first reflecting mirror 430. The first reflecting mirror 430 is located on one side of the dichroic mirror 420 and reflects signal light to the second collimating component 50.
[0090] The combination of the dichroic mirror 420 and the first reflecting mirror 430 enables the transmission of pump light and the reflection of signal light. The dichroic mirror 420 is located between the first collimating component 30 and the second collimating component 50. On one hand, the dichroic mirror 420 transmits the collimated pump light output from the first collimating component 30 to the second collimating component 50. On the other hand, the signal light output from the core of the output pigtail 60 is focused by the second collimating component 50 and transmitted to the dichroic mirror 420, where it is then reflected back to the first reflecting mirror 430. The first reflecting mirror 430 then reflects the optical signal back to the second collimating component 50, which further couples the collimated signal light back to the core of the output pigtail 60.
[0091] For example, the wavelength-selective reflection component 40 highly reflects the signal light of the second wavelength output from the fiber core of the output pigtail 60, and calibrates the signal light with the highest fiber core coupling efficiency when the fiber core fundamental mode is reflected back to the fiber core.
[0092] Figure 4 This is a schematic diagram of the structure of the multimode laser 100. Figure 4 and Figure 3The difference lies in the structure of the wavelength-selective reflective component 40. (Combined) Figure 4 In other examples, the wavelength-selective reflection component 40 includes a first volume Bragg grating 410. The first volume Bragg grating 410 is located between the first collimation component 30 and the second collimation component 50, and is used to transmit pump light to the second collimation component 50 and reflect signal light to the second collimation component 50.
[0093] The first-volume Bragg grating 410 transmits the collimated pump light output from the first collimating component 30 to the second collimating component 50. Simultaneously, the signal light output from the core of the output pigtail 60 is focused by the second collimating component 50 and transmitted to the first-volume Bragg grating 410, then reflected back to the second collimating component 50. The second collimating component 50 further couples the collimated signal light back to the core of the output pigtail 60. This design achieves both pump light transmission and signal light reflection using only the first-volume Bragg grating 410, improving the integration of the multimode laser 100 and making its structure more compact.
[0094] In this embodiment, the wavelength-selective reflection component 40 highly reflects the signal light of the second wavelength output from the output pigtail 60, and calibrates the fiber core coupling efficiency based on the reflection of the fiber core fundamental mode back to the fiber core.
[0095] See you again Figure 2 In this embodiment, when the pump light is transmitted along the second path, the wavelength selective reflection component 40 is located at the end of the core of the output pigtail 60.
[0096] In the above implementation, the wavelength reflection component is directly placed at the end of the fiber core of the output pigtail 60, which effectively simplifies the structure of the wavelength selective reflection component 40 and helps to improve the structural compactness of the multimode laser 100. Furthermore, the assembly process of the wavelength selective reflection component 40 is omitted during the assembly of the multimode laser 100, effectively reducing the assembly difficulty.
[0097] Figure 5 This is a schematic diagram of the structure of the multimode laser 100. Figure 5 and Figure 3 The difference lies in the structure of the wavelength selective reflective component 40 and the location of the wavelength selective reflective component 40. Combined with... Figure 5 For example, the wavelength selective reflection component 40 includes a dielectric film 440. The dielectric film 440 is located at the end of the output pigtail 60 and is used to transmit pump light to the inner cladding of the output pigtail 60 and reflect signal light to the core of the output pigtail 60.
[0098] In the above implementation, the dielectric film 440 can transmit the collimated pump light output from the second collimating component 50 to the inner cladding of the output pigtail 60, and can also reflect the signal light output from the core of the output pigtail 60 back to the core of the output pigtail 60. This design allows for both the transmission of pump light and the reflection of signal light solely through the dielectric film 440, which improves the integration of the multimode laser 100 and makes its structure more compact.
[0099] The structure and position of the wavelength selective reflection component 40 have been described above. The first collimation component 30 will be described below.
[0100] See you again Figure 3 In this embodiment, the first collimating assembly 30 includes a fast-axis collimating lens 310 (fac) and a slow-axis collimating lens 320 (sac). The fast-axis collimating lens 310 and the slow-axis collimating lens 320 are opposite to each other, with the fast-axis collimating lens 310 being closer to the laser unit 20 and opposite to the output port of the laser unit 20.
[0101] In the above implementation, the fast-axis collimating lens 310 and the slow-axis collimating lens 320 work together to effectively collimate the pump light of the first wavelength.
[0102] Figure 6 This is a schematic diagram of the structure of the multimode laser 100. Figure 6 and Figure 3 The difference lies in the structure of the first collimation component 30. For example, the first collimation component 30 also includes a second volume Bragg grating 330. The second volume Bragg grating 330 is located between the fast-axis collimating lens 310 and the slow-axis collimating lens 320.
[0103] In the above implementation, a second body Bragg grating 330 is also provided between the fast-axis collimating lens 310 and the slow-axis collimating lens 320. The second body Bragg grating 330 can reflect part of the pump light of the first wavelength, thereby used for wavelength locking of the laser unit 20 to ensure that the laser unit 20 can always output the pump light of the first wavelength.
[0104] See you again Figure 3 In this embodiment, there are multiple laser units 20, and each laser unit 20 is arranged sequentially.
[0105] The first collimation component 30 corresponds one-to-one with the laser unit 20, and the arrangement direction of each first collimation component 30 is consistent with the arrangement direction of each laser unit 20.
[0106] The multimode laser 100 also includes a second reflector 70, which corresponds one-to-one with the first collimation component 30. The arrangement direction of each second reflector 70 is consistent with the arrangement direction of each first collimation component 30. Each second reflector 70 is used to combine the pump light output from each first collimation component 30 into a single beam and couple it to the wavelength-selective reflection component 40 or the second collimation component 50.
[0107] In the above implementation, since the first collimating component 30 corresponds one-to-one with the laser unit 20, the pump light output from each laser unit 20 can be transmitted to the corresponding first collimating component 30 and thus collimated by the first collimating component 30. Furthermore, since the second reflecting mirror 70 corresponds one-to-one with the first collimating component 30, each second reflecting mirror 70 can combine the collimated pump light output from each first collimating component 30 into a single beam, thus completing the spatial beam combining of the pump light beams.
[0108] After spatial beam combining, if the pump light propagates along the first path (see...) Figure 3 If the signal is transmitted along the second path, it will be coupled to the wavelength selective reflector 40; if the signal is transmitted along the second path, it will be coupled to the second collimator 50 (see [link]). Figure 4 ).
[0109] In this embodiment, the number of laser units 20 is 4 to 6. Of course, in other embodiments, the number of laser units 20 can also be adjusted according to actual needs, such as 3 or 7, etc., and this application does not limit this.
[0110] For example, the laser unit 20 is a multimode LD (laser diode) chip.
[0111] The optical path of the multimode laser 100 is described below.
[0112] For the first path:
[0113] The laser unit 20 outputs pump light of the first wavelength, which is transmitted sequentially through the inner cladding of the first collimation component 30, the second reflector 70, the wavelength selective reflection component 40, the second collimation component 50, and the output pigtail 60.
[0114] The second wavelength signal light output from the core of the output pigtail 60 is transmitted sequentially through the second collimation component 50, the wavelength selective reflection component 40, the second collimation component 50, and the core of the output pigtail 60.
[0115] For the second path:
[0116] The laser unit 20 outputs pump light of the first wavelength, which is transmitted sequentially through the inner cladding of the first collimation component 30, the second reflector 70, the second collimation component 50, the wavelength selective reflection component 40, and the output pigtail 60.
[0117] The core of the output pigtail 60 outputs a second wavelength signal light in reverse. After the second wavelength signal light is transmitted to the wavelength selective reflection component 40, it is reflected by the wavelength selective reflection component 40 and thus coupled back into the core of the output pigtail 60.
[0118] Figure 7 A frame diagram of a pump laser provided in this application embodiment, combined with Figure 7 In this embodiment, the pump laser includes Figures 1 to 6 The multimode laser 100, gain fiber 200, and partial optical reflector 300 are shown.
[0119] One end of the gain fiber 200 is connected to the output pigtail 60, and the inner cladding 202 of the gain fiber 200 is connected to the inner cladding of the output pigtail 60. The core 201 of the gain fiber 200 is connected to the core of the output pigtail 60. The core 201 of the gain fiber 200 can generate and transmit signal light of the second wavelength under the action of the pump light of the first wavelength.
[0120] Partial optical reflector 300 is connected to the other end of gain fiber 200. Partial optical reflector 300 is used to transmit the first part of the signal light and reflect the second part of the signal light, so that the second part of the signal light resonates between partial optical reflector 300 and wavelength selective reflection component 40.
[0121] The pump laser provided in this application embodiment has at least the following effects:
[0122] have Figures 1 to 6 The multimode laser 100 shown has a compact structure and, compared to the single-mode lasers mentioned in related technologies, has a larger maximum output power, which is beneficial for improving the maximum output power of the pump laser. The gain fiber 200 includes a core and an inner cladding. The pump light of the first wavelength output by the multimode laser 100 propagates through the inner cladding 202 of the gain fiber 200, resulting in a significant gain in the core 201 of the gain fiber 200 and generating a signal light of the second wavelength. Furthermore, under the action of the partial optical reflector 300, the signal light in the core 201 of the gain fiber 200 resonates between the partial optical reflector 300 and the wavelength selective reflection component 40, thereby generating quasi-single-mode stimulated emission of the second wavelength.
[0123] As mentioned above, the gain fiber 200 plays a crucial role in the gain and generation of the second wavelength signal light. The gain fiber 200 will be described below.
[0124] Figure 8 This is a cross-sectional view of the gain fiber 200, combined with... Figure 8 In this embodiment, the gain fiber 200 includes a core 201, an inner cladding 202, and an outer cladding 203. The inner cladding 202 wraps around the core 201, and the outer cladding 203 wraps around the inner cladding 202.
[0125] The type of gain fiber 200 is adjusted according to the first wavelength and the second wavelength.
[0126] In some examples, when the first wavelength is 930nm to 950nm and the second wavelength is 972nm to 982nm, the core 201 of the gain fiber 200 is made of germanium-doped silica glass, the inner cladding 202 of the gain fiber 200 is made of germanium-doped silica glass, and the refractive index of the core 201 of the gain fiber 200 is higher than the refractive index of the inner cladding 202 of the gain fiber 200.
[0127] In the above implementation, the 972nm-982nm band is the preferred pump band for erbium-doped fiber amplifiers, as it can overlap with the erbium ion absorption band, which helps to achieve high population inversion and obtain excellent noise figure.
[0128] The design of the core 201 and inner cladding material of the gain fiber 200 enables significant gain to be generated in the core 201 of the gain fiber 200 and to generate signal light of the second wavelength.
[0129] In this embodiment, although both the core 201 and the inner cladding 202 of the gain fiber 200 are germanium-doped, their doping concentrations are different. The doping concentration of the core 201 of the gain fiber 200 is higher than that of the inner cladding 202.
[0130] In this embodiment, the first wavelength is 940nm and the second wavelength is 980nm.
[0131] In this embodiment, the refractive index of the core 201 of the gain fiber 200 is 1.503, the refractive index of the inner cladding of the gain fiber 200 is 1.501, and the refractive index of the outer cladding of the gain fiber 200 is 1.451.
[0132] Regarding the dimensions of the gain fiber 200, for the core 201 of the gain fiber 200, the radius of the core 201 is 5μm to 10μm, and the numerical aperture of the core 201 is greater than 0.05. For the inner cladding 202 of the gain fiber 200, the radius of the inner cladding 202 is 17μm to 30μm, and the numerical aperture of the inner cladding 202 is greater than 0.38.
[0133] The design of the core 201 and inner cladding parameters of the gain fiber 200 can effectively improve the overall conversion efficiency of the gain fiber 200.
[0134] In this embodiment, the core 201 of the gain fiber 200 has a radius of 8.5 μm, the inner cladding 202 of the gain fiber 200 has a radius of 25 μm, and the outer cladding 203 of the gain fiber 200 has a radius of 62.5 μm.
[0135] For example, the outer surface of the cladding 203 of the gain fiber 200 is provided with an acrylic coating layer, which can protect the gain fiber 200 and effectively improve the reliability of the gain fiber 200.
[0136] In this embodiment, the radius of the acrylate coating layer of the gain fiber 200 is 125 μm.
[0137] For example, the length of the gain fiber 200 is 25 to 100 meters. The length of the gain fiber 200 is determined based on factors such as germanium doping concentration, attenuation coefficient, and pump power, and this application does not impose any limitations on it.
[0138] In the above implementation, the gain fiber 200 is a double-clad high Raman gain fiber. The pump light of the first wavelength (940nm) is coupled to the inner cladding 202 of the gain fiber 200. Under the action of stimulated Raman scattering, the band corresponding to the second wavelength generates a significant gain and produces random spontaneous emission noise. The spontaneous emission noise resonates between the partial optical reflector 300 and the wavelength selective reflector 40, generating stimulated emission of the second wavelength. Since the cavity loss of the fundamental mode is the lowest, the Raman gain obtained is the highest, gaining a competitive advantage over other modes. The fundamental mode is selectively amplified and accounts for the highest proportion of output power, forming a quasi-single-mode output.
[0139] In other examples, when the first wavelength is 905nm to 925nm and the second wavelength is 972nm to 982nm, the core 201 of the gain fiber 200 is made of ytterbium-doped silica glass and the inner cladding 202 of the gain fiber 200 is made of germanium-doped silica glass.
[0140] In the above implementation, the 972nm-982nm band is the preferred pump band for erbium-doped fiber amplifiers, as it can overlap with the erbium ion absorption band, which helps to achieve high population inversion and obtain excellent noise figure.
[0141] The design of the core 201 and inner cladding material of the gain fiber 200 enables significant gain to be generated in the core 201 of the gain fiber 200 and to generate signal light of the second wavelength.
[0142] In this embodiment, the first wavelength is 915nm and the second wavelength is 980nm.
[0143] In this embodiment, the refractive index of the core 201 of the gain fiber 200 is 1.453, the refractive index of the inner cladding of the gain fiber 200 is 1.451, and the refractive index of the outer cladding of the gain fiber 200 is 1.380.
[0144] Regarding the dimensions of the gain fiber 200, for the core 201 of the gain fiber 200, the radius of the core 201 is 5μm to 10μm, and the numerical aperture of the core 201 is greater than 0.05. For the inner cladding 202 of the gain fiber 200, the radius of the inner cladding 202 is 17μm to 30μm, and the numerical aperture of the inner cladding 202 is greater than 0.45.
[0145] The design of the core 201 and inner cladding parameters of the gain fiber 200 can effectively improve the overall conversion efficiency of the gain fiber 200.
[0146] In this embodiment, the core 201 of the gain fiber 200 has a radius of 7.5 μm, the inner cladding 202 of the gain fiber 200 has a radius of 25 μm, and the outer cladding 203 of the gain fiber 200 has a radius of 80 μm.
[0147] For example, the length of the gain fiber 200 is 0.1 to 10 meters. The length of the gain fiber 200 is determined based on factors such as germanium doping concentration, attenuation coefficient, and reflectivity of some optical reflectors 300, and this application does not impose any limitations on this.
[0148] In the above implementation, the pump light of the first wavelength (915nm) is coupled to the inner cladding 202 of the gain fiber 200. During transmission through the inner cladding 202, it is absorbed by ytterbium ions in the core 201 of the gain fiber 200 and excited to the upper energy level. Under stimulated emission, the band corresponding to the second wavelength generates a significant gain and produces random spontaneous emission noise. The spontaneous emission noise resonates between the partial optical reflector 300 and the wavelength selective reflective component 40.
[0149] In this embodiment, in order to maximize the conversion efficiency from the pump light of the first wavelength (915nm) to the quasi-single-mode signal light of the second wavelength, the wavelength selective reflector 40 and the partial reflector 300 reduce the reflectivity in the 1.0 to 1.1µm band as much as possible, so as to suppress the accumulation of ASE (amplified spontaneous emission) in this band and consume the upper-level particles to reduce the inversion rate.
[0150] In this embodiment, a portion of the optical reflector 300 is fabricated using fiber Bragg grating technology and inscribed on the core 201 of the gain fiber 200. It reflects 980nm wavelength signal light within the core, with a reflectivity of 20% and a transmittance of 80%. The transmitted signal light is the first portion of the signal light, and the reflected signal light is the second portion of the signal light.
[0151] Of course, in other embodiments, the reflectivity and transmittance of some light reflectors 300 for signal light can also be adjusted according to actual needs, and this application does not limit this.
[0152] The optical path of the pump laser is explained below.
[0153] For the first path:
[0154] The laser unit 20 outputs pump light of the first wavelength, which is transmitted sequentially through the first collimation component 30, the second reflector 70, the wavelength selective reflector 40, the second collimation component 50, the inner cladding of the output pigtail 60, the inner cladding of the gain fiber 200, and the partial light reflector 300.
[0155] Partial optical reflector 300 reflects a portion of the second wavelength signal light, which then sequentially passes through the core 201 of gain fiber 200, the core of output pigtail 60, the second collimating component 50, and the wavelength selective reflector 40. Afterward, the second wavelength signal light is reflected by the wavelength selective reflector 40, focused by the second collimating component 50, and then coupled back into the core of output pigtail 60, causing a portion of the second wavelength signal light to resonate between partial optical reflector 300 and wavelength selective reflector 40.
[0156] For the second path:
[0157] The laser unit 20 outputs pump light of the first wavelength, which is transmitted sequentially through the first collimation component 30, the second reflector 70, the second collimation component 50, the wavelength selective reflection component 40, the inner cladding of the output pigtail 60, the inner cladding of the gain fiber 200, and the partial light reflector 300.
[0158] Partial optical reflector 300 reflects a portion of the second wavelength signal light. The second wavelength signal light is transmitted sequentially through the fiber core 201 of gain fiber 200 and the fiber core of output pigtail 60. After being transmitted to wavelength selective reflection component 40, it is reflected by wavelength selective reflection component 40 and thus coupled back into the fiber core of output pigtail 60, so that part of the second wavelength signal light resonates between partial optical reflector 300 and wavelength selective reflection component 40.
[0159] Figure 9A frame diagram of an optical amplifier provided in this application embodiment, combined with Figure 9 In this embodiment, the optical amplifier includes a first optical isolator 11, a pump combiner 21, an erbium-doped fiber 31, a second optical isolator 41, and Figure 7 The pump laser shown.
[0160] The first optical isolator 11, the pump combiner 21, the erbium-doped fiber 31, and the second optical isolator 41 are connected in sequence. The partial optical reflector 300 of the pump laser is connected to the pump combiner 21, so that the amplified signal light can be transmitted to the pump combiner 21.
[0161] In the above implementation, the pump laser is connected to the optical amplifier through the pump combiner 21 and can provide a second wavelength optical signal.
[0162] Figure 10 This is a frame diagram of another optical amplifier provided in an embodiment of this application, combined with... Figure 10 , Figure 10 and Figure 9 The difference is that, Figure 10 The optical amplifier shown in the video consists of multiple Figure 9 The optical amplifiers shown are connected in parallel, forming a parallel optical amplifier.
[0163] In this embodiment, the optical amplifier includes multiple first optical isolators 11, multiple pump combiners 21, multiple erbium-doped fibers 31, multiple second optical isolators 41, and one... Figure 7 The pump laser shown.
[0164] The first optical isolator 11, the pump combiner 21, the erbium-doped fiber 31, and the second optical isolator 41 are connected in sequence. The partial optical reflectors 300 of the pump laser are connected to each pump combiner 21, so that the amplified signal light can be transmitted to each pump combiner 21.
[0165] In the above implementation, the pump laser is connected to the optical amplifier through the pump combiner 21 and can provide a second wavelength optical signal.
[0166] Figure 11 This is a frame diagram of another optical amplifier provided in an embodiment of this application, combined with... Figure 11 The optical amplifier includes a first-band sub-optical amplifier, a second-band optical amplifier, and... Figure 7 The pump laser shown.
[0167] The first-band sub-optical amplifier and the second-band optical amplifier both include a first optical isolator 12, a pump combiner 22, an erbium-doped fiber 32, and a second optical isolator 42.
[0168] In the first-band sub-optical amplifier, the first optical isolator 12, the pump combiner 22, the erbium-doped fiber 32, and the second optical isolator 42 are connected in sequence. The partial optical reflector 300 of the pump laser is connected to the pump combiner 22, so that the amplified signal light can be transmitted to the pump combiner 22.
[0169] In the second-band sub-optical amplifier, the first optical isolator 12, the pump combiner 22, the erbium-doped fiber 32, and the second optical isolator 42 are connected in one step. The partial optical reflector 300 of the pump laser is connected to the pump combiner 22, so that the amplified signal light can be transmitted to the pump combiner 22.
[0170] The optical amplifier also includes a first-band multiplexer / demultiplexer 52 and a second-band multiplexer / demultiplexer 62. The first optical isolators 12 of the first-band sub-optical amplifier and the second-band optical amplifier are connected via the first-band multiplexer / demultiplexer 52, respectively. The second optical isolators 42 of the first-band sub-optical amplifier and the second-band optical amplifier are connected via the second-band multiplexer / demultiplexer 62, respectively. A portion of the pump laser's optical reflector 300 is connected to the pump multiplexer 22 of both the first-band and second-band optical amplifiers.
[0171] In the above implementation, the optical amplifier constitutes a dual-band optical amplifier, such as a (C+L) band optical amplifier.
[0172] This application provides a communication system, including... Figure 9 , Figure 10 ,or Figure 11 The optical amplifier shown.
[0173] Because the communication system includes Figure 9 , Figure 10 ,or Figure 11 The optical amplifier shown indicates that the communication system possesses... Figure 9 , Figure 10 ,or Figure 11 The full range of beneficial effects of the optical amplifier shown will not be elaborated upon here.
[0174] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.
[0175] The above specific embodiments further illustrate the purpose, technical solution and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solution of this application should be included within the scope of protection of this application.
Claims
1. A multimode laser, characterized in that, It includes a housing (10), and a laser unit (20), a first collimation component (30), a wavelength selective reflection component (40), a second collimation component (50), and an output pigtail (60) located within the housing (10); The laser unit (20) is used to output pump light of a first wavelength. The pump light can be transmitted along a first path or a second path. The first path is composed of the first collimation component (30), the wavelength selective reflection component (40), the second collimation component (50), and the inner cladding of the output pigtail (60). The second path is composed of the first collimation component (30), the second collimation component (50), the wavelength selective reflection component (40), and the inner cladding of the output pigtail (60). The wavelength selective reflector (40) is used to reflect the signal light of a second wavelength output from the core of the output pigtail (60), the second wavelength being greater than the first wavelength.
2. The multimode laser according to claim 1, characterized in that, When the pump light is transmitted along the first path, the wavelength selective reflection component (40) and the second collimation component (50) are an integral structural component.
3. The multimode laser according to claim 2, characterized in that, The wavelength selective reflection component (40) includes a first volume Bragg grating (410); The first volume Bragg grating (410) is located between the first collimation component (30) and the second collimation component (50). The first volume Bragg grating (410) is used to transmit the pump light to the second collimation component (50) and reflect the signal light to the second collimation component (50).
4. The multimode laser according to claim 2, characterized in that, The wavelength selective reflection component (40) includes a dichroic mirror (420) and a first reflector (430); The dichroic mirror (420) is located between the first collimating component (30) and the second collimating component (50). The dichroic mirror (420) is used to transmit the pump light to the second collimating component (50) and reflect the signal light to the first reflecting mirror (430). The first reflector (430) is located on one side of the dichroic mirror (420) and is used to reflect the signal light to the second collimation component (50).
5. The multimode laser according to claim 1, characterized in that, When the pump light is transmitted along the second path, the wavelength selective reflector (40) is located at the end of the core of the output pigtail (60).
6. The multimode laser according to claim 5, characterized in that, The wavelength selective reflective component (40) includes a dielectric film (440); The dielectric film (440) is located at the end of the output pigtail (60). The dielectric film (440) is used to transmit the pump light to the inner cladding of the output pigtail (60) and reflect the signal light to the core of the output pigtail (60).
7. The multimode laser according to any one of claims 1 to 6, characterized in that, The number of laser units (20) is multiple, and the laser units (20) are arranged in sequence; The first collimation component (30) corresponds one-to-one with the laser unit (20), and the arrangement direction of each first collimation component (30) is consistent with the arrangement direction of each laser unit (20); The multimode laser also includes a second mirror (70), which corresponds one-to-one with the first collimation component (30). The arrangement direction of each second mirror (70) is consistent with the arrangement direction of each first collimation component (30). Each second mirror (60) is used to combine the pump light output from each first collimation component (30) into a beam and couple it to the wavelength selective reflection component (40) or the second collimation component (50).
8. A pump laser, characterized in that, It includes a multimode laser (100), a gain fiber (200), and a partial optical reflector (300); The multimode laser (100) is the multimode laser (100) according to any one of claims 1 to 7; One end of the gain fiber (200) is connected to the output pigtail (60), and the inner cladding (202) of the gain fiber (200) is connected to the inner cladding of the output pigtail (60). The core (201) of the gain fiber (200) is connected to the core of the output pigtail (60). The core (201) of the gain fiber (200) can generate and transmit the signal light of the second wavelength under the action of the pump light of the first wavelength. The partial optical reflector (300) is connected to the other end of the gain fiber (200). The partial optical reflector (300) is used to transmit the first part of the signal light and reflect the second part of the signal light, so that the second part of the signal light resonates between the partial optical reflector (300) and the wavelength selective reflection component (40).
9. The pump laser according to claim 8, characterized in that, When the first wavelength is 930nm~950nm and the second wavelength is 972nm~982nm, the core (201) of the gain fiber (200) is made of germanium-doped silica glass, the inner cladding (202) of the gain fiber (200) is made of germanium-doped silica glass, and the refractive index of the core (201) of the gain fiber (200) is higher than the refractive index of the inner cladding (202) of the gain fiber (200).
10. The pump laser according to claim 9, characterized in that, The core (201) of the gain fiber (200) has a radius of 5μm to 10μm, and the numerical aperture of the core (201) of the gain fiber (200) is greater than 0.
05. The inner cladding (202) of the gain fiber (200) has a radius of 17μm to 30μm, and the numerical aperture of the inner cladding (202) of the gain fiber (200) is greater than 0.
38.
11. The pump laser according to claim 8, characterized in that, When the first wavelength is 905nm~925nm and the second wavelength is 972nm~982nm, the core (201) of the gain fiber (200) is made of ytterbium-doped silica glass and the inner cladding (202) of the gain fiber (200) is made of germanium-doped silica glass.
12. The pump laser according to claim 11, characterized in that, The core (201) of the gain fiber (200) has a radius of 5μm to 10μm, and the numerical aperture of the core (201) of the gain fiber (200) is greater than 0.
05. The inner cladding (202) of the gain fiber (200) has a radius of 17μm to 30μm, and the numerical aperture of the inner cladding (202) of the gain fiber (200) is greater than 0.
45.
13. An optical amplifier, characterized in that, Includes the pump laser as described in any one of claims 8 to 12.
14. A communication system, characterized in that, Includes the optical amplifier as described in claim 13.