Tunable laser

Abstract

The present invention provides a tunable laser, comprising an amplifier and an FP optical filter, wherein the amplifier is provided with an amplifier output end, a signal output end and a signal input end, the FP optical filter is provided with a filter input end and a filter output end, the filter input end is connected to the amplifier output end through a first optical fiber, the filter output end is connected to the signal input end through a second optical fiber, the amplifier is further provided with a first amplifier optical path, an output optical path, a transflective element and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifier output end are arranged along the first amplifier optical path, the transflective element is arranged on the first amplifier optical path, the transflective element is located at the front stage or the rear stage of the first semiconductor optical amplifier, and the transflective element and the signal output end are arranged along the output optical path. The amplifier, the first optical fiber, the FP optical filter and the second optical fiber constitute a closed annular cavity, and the necessary components are arranged in an integrated manner, which can not only shorten the length of the annular cavity, but also ensure the stability of the entire annular cavity.

Description

Technical Field

[0001] The invention relates to the field of optical devices, and in particular to a tunable laser. Background Art

[0002] Single-frequency tunable lasers and high-speed wavelength swept lasers are widely used in many fields, such as optical coherence tomography (OCT), biochemical spectroscopy, fiber optic sensing applications, and optical communications. In order to achieve widespread commercial applications, compact and stable tunable laser sources are essential.

[0003] In actual use, the various components of the ring cavity, including semiconductor optical amplifiers, optical isolators, couplers, and optical filters, are generally connected by fiber fusion splicing, which makes it difficult to produce a shorter ring cavity, which is the basis for discrete single-frequency tuning and fast frequency sweeping. In addition, when the cavity length is long, the connection of many components will lead to a more complex laser layout structure, which is not conducive to the design trend of miniaturization. Summary of the invention

[0004] The object of the present invention is to provide a tunable laser with an integrated arrangement and a short cavity length.

[0005] In order to achieve the purpose of the present invention, the present invention provides a tunable laser, including an amplifier and an FP optical filter device, the amplifier is provided with an amplifier output end, a signal output end and a signal input end, the FP optical filter device is provided with a filter input end and a filter output end, the filter input end is connected to the amplifier output end through a first optical fiber, and the filter output end is connected to the signal input end through a second optical fiber, the amplifier is also provided with a first amplifier optical path, an output optical path, a transflective element and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifier output end are arranged along the first amplifier optical path, the transflective element is arranged on the first amplifier optical path, the transflective element is located at the front stage or the rear stage of the first semiconductor optical amplifier, and the transflective element and the signal output end are arranged along the output optical path.

[0006] As can be seen from the above scheme, by connecting the filter input end and the amplifier output end through the first optical fiber, connecting the filter output end and the signal input end through the second optical fiber, and arranging the signal input end, the first semiconductor optical amplifier and the amplifier output end along the first amplifier optical path, the signal obtained by the FP optical filter device filtering process is input to the first semiconductor optical amplifier for amplification, and the transflective element is arranged at the front stage or the rear stage of the first semiconductor optical amplifier, so that the amplification before or after the amplification is output through the signal output end, and the necessary components of the tunable laser are arranged in an integrated manner, the cavity length of the ring cavity can be greatly reduced, thereby effectively realizing discrete single-frequency laser tuning and supporting higher-speed swept-frequency lasers. In the entire ring cavity, one-way transmission of light is achieved by connecting two optical isolators before and after the SOA chip.

[0007] A further solution is that the amplifier device is also provided with a first reflector, the first reflector is arranged on the output light path, the first reflector is located between the signal output end and the transflective element, and the signal output end and the amplifier output end or the signal input end are located on the same side.

[0008] A further solution is that the first reflective element is located on the reflective side of the transflective element.

[0009] As can be seen from the above, by adjusting the optical path through the arrangement of the reflector, the amplifier output end and the signal output end or the signal input end can be located on the same side, thereby optimizing the port arrangement, facilitating fiber winding, facilitating miniaturized arrangement, and improving stability.

[0010] A further solution is that the amplifying device is further provided with a second semiconductor optical amplifier, the second semiconductor optical amplifier is arranged on the output optical path, and the second semiconductor optical amplifier is located between the amplifying output end and the first transflective element.

[0011] It can be seen from the above that after the signal is output from the transflective element, it can be amplified by the second semiconductor optical amplifier and then output.

[0012] A further solution is that the amplifying device further comprises a first optical fiber base and a second optical fiber base, the output end of the first optical fiber is arranged on the first optical fiber base, and the input end of the second optical fiber base is arranged on the second optical fiber base.

[0013] A further solution is that the amplifying device also sets a first optical isolator and a second optical isolator at both ends of the first semiconductor optical amplifier on the first amplified optical path, the first optical isolator is located at the front end of the first semiconductor optical amplifier, and the second optical isolator is located at the rear end of the first semiconductor optical amplifier.

[0014] A further solution is that the first optical isolator is an optical isolator with a collimating lens, and the second optical isolator is an optical isolator with a focusing lens and a collimating lens.

[0015] As can be seen from the above, the optical fiber is directly positioned through the optical fiber base, the one-way light transmission effect of the optical isolator is coordinated, and the coupling efficiency and overall output quality are improved through the collimating lens and focusing lens.

[0016] A further solution is that the first optical fiber and / or the second optical fiber is a polarization-maintaining optical fiber.

[0017] As can be seen from the above, the polarization direction can be maintained in the annular cavity by using a sufficiently short length of the optical fiber pigtail. When a long cavity length is required, a polarization-maintaining fiber can be used for connection.

[0018] A further solution is that the amplifying device is further provided with a bearing base and a semiconductor refrigerator, the bearing base is arranged on the first heat conduction end of the semiconductor refrigerator, and the first semiconductor optical amplifier is arranged on the bearing base.

[0019] A further solution is that the amplifying device also includes a packaging shell, which encloses a closed accommodating cavity, in which the transflective element, the first semiconductor optical amplifier, the supporting base and the semiconductor refrigerator are arranged, and the second heat conduction end of the semiconductor refrigerator is connected to the packaging shell.

[0020] As can be seen from the above, through the closed design of the packaging shell, the semiconductor refrigerator can control the temperature inside the packaging shell, as well as the temperature of the semiconductor optical amplifier. When the temperature is too high, the semiconductor optical amplifier is cooled down, and when the temperature is too low, the semiconductor optical amplifier is heated. In this way, the semiconductor optical amplifier is always kept at the optimal operating temperature, thereby improving the stability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the first embodiment of the tunable laser of the present invention.

[0022] Figure 2 It is a schematic diagram of the structure of the amplifying device in the first embodiment of the tunable laser of the present invention.

[0023] Figure 3 It is a cross-sectional view of the amplifying device in the first embodiment of the tunable laser of the present invention.

[0024] Figure 4 It is a transmission schematic diagram of the tunable laser embodiment of the present invention in single-frequency mode.

[0025] Figure 5 It is a transmission schematic diagram of the tunable laser embodiment of the present invention in a multi-frequency mode.

[0026] Figure 6 It is a schematic diagram of the structure of the amplifying device in the second embodiment of the tunable laser of the present invention.

[0027] Figure 7 It is a schematic diagram of the structure of the amplifying device in the third embodiment of the tunable laser of the present invention.

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0029] The first embodiment of tunable laser:

[0030] Reference Figure 1 Medium to Figure 3The tunable laser comprises a housing 11, an amplifier 2 and a FP optical filter 3, the amplifier 2 and the FP optical filter 3 are placed in the housing 11, the FP optical filter 3 comprises a package shell and a FP filter device combination arranged in the package shell, the specific structure of the FP optical filter 3 can refer to the invention patent application with publication number CN109557617A and the name of "tunable filter" applied by the applicant, and can also refer to the invention patent application with publication number CN109491018A and the name of "fast tunable filter", both of which disclose the detailed structure of the FP optical filter device in detail, through the relative arrangement of the output ends of the two optical fiber ferrules, and the combination of one or two piezoelectric ceramics, not only can slow large-range frequency tuning be achieved, but also fast tuning and frequency scanning can be achieved by using high-frequency vibration. The FP optical filter 3 is provided with a filter input end 32 and a filter output end 31 at the opposite ends of the package shell.

[0031] The amplifying device 2 includes a packaging shell 21, which includes a base and a cover. The base and the cover form a closed accommodating cavity. The packaging shell 21 is provided with an amplifying output terminal 222, a signal output terminal 223 and a signal input terminal 221 on the side wall. In this embodiment, the signal output terminal 223 and the signal input terminal 221 are located on the same side, and the signal input terminal 221 and the amplifying output terminal 222 are located on the opposite side. Protective tubes are provided on the input terminal and the output terminal, and a through hole is provided through the protective tube.

[0032] The filter input end 32 is connected to the amplifier output end 222 through the first optical fiber 132, and the filter output end 31 is connected to the signal input end 221 through the second optical fiber 131. Since the amplifier 2 and the FP optical filter device 3 are arranged close to each other in the same housing 11, the length of the second optical fiber 131 of the first optical fiber 132 can not only be accurately controlled, but also the length of the optical fiber can be effectively shortened, thereby shortening the cavity length of the laser. In addition, the first optical fiber 132 and / or the second optical fiber 131 can be connected using a polarization-maintaining optical fiber.

[0033] The amplifying device 2 in the embodiment 1 is further provided with a first amplifying optical path, an output optical path, a transflective element 251, a first semiconductor optical amplifier 261, a first reflecting element 27, a combined glass 25, an optical isolator 241, a lens 242, an optical isolator 243, a lens 244, an optical fiber base 271, an optical fiber base 272, an optical fiber base 273, a supporting base 231 and a semiconductor refrigerator 232. The signal input terminal 221, the optical isolator 241, the transflective element 251, the lens 242, the first semiconductor optical amplifier 261, the optical isolator 243 and the amplifying output terminal 222 are sequentially arranged along the first amplifying optical path. Then the transflective element 251 is located at the front stage of the first semiconductor optical amplifier 261. The optical fiber base 271, the optical isolator 241, the transflective element 251 and the first semiconductor optical amplifier 261 are arranged in sequence. The reflective element 251, the combined glass 25, the lens 242, the first semiconductor optical amplifier 261, the optical isolator 243 and the optical fiber base 272 are arranged on the supporting base 231, the first optical fiber 132 penetrates into the signal input end 221, the optical fiber base 271 fixes the output end of the first optical fiber 132 by glue, and the optical fiber base 272 fixes the input end of the second optical fiber 132 by glue. The combined glass 25 is bonded by two right-angle prisms, specifically, the inclined surface of one right-angle prism is connected to the right-angle surface of the other right-angle prism, and a transflective element 251 is arranged between the inclined surface and the right-angle surface. The transflective element 251 adopts a transflective film with a preset transflective ratio, the transmittance is T, the reflectance is R, and the transflective element 251 is arranged at an angle of 45° with the first amplifying optical path. The lens 242 and the lens 244 adopt focusing lenses, the optical isolator 241 is an optical isolator with a collimating lens, and the optical isolator 243 is an optical isolator with a focusing lens and a collimating lens.

[0034] The first reflector 27 is a reflective film, which is arranged on the right angle surface of the combined glass 25 on the other side opposite to the transflective member 251. The first reflector 27 is perpendicular to the transflective member 251, and is located on the reflection side of the transflective member 251. The lens 242 is located on the transmission side of the transflective member 251. The transflective member 251, the first reflector 27 and the signal output end 223 are arranged in sequence along the output optical path. By adjusting the direction of the optical path by the first reflector 27, the amplified output end 222 and the signal input end 221 are located on the same side. The signal input end 221 is provided with an output optical fiber 133, the input end of the output optical fiber 133 is fixed by a fiber base 273 through glue, and the output end of the output optical fiber 133 is provided with a connector 12.

[0035] The semiconductor cooler 232 is located in the accommodating cavity and is arranged on the bottom wall of the packaging shell 21. The supporting base 231 is arranged on the first heat conduction end of the semiconductor cooler 232. The second heat conduction end of the semiconductor cooler 232 is connected to the bottom wall of the packaging shell 21. Since the first semiconductor optical amplifier 261 is arranged on the supporting base 231, heat conduction between the semiconductor optical amplifier and the supporting base can be realized. The side wall of the packaging shell 21 is provided with a connecting pin 211.

[0036] Reference Figure 4 and Figure 5 , and combined with Figures 1 to 3 , Figure 4 This is a schematic diagram of the transmission of a tunable laser in single-frequency mode. Figure 5 This is a schematic diagram of the transmission of a tunable laser in multi-frequency mode.

[0037] After the light is emitted from the second optical fiber 131, it passes through the optical isolator 241 with a collimating lens, and then is emitted to the combined glass 25 containing the transflective element 251 and the first reflective element 27. After the light beam passes through the front end face of the combined glass with the anti-reflection film, it reaches the transflective element 251, where the reflected light will be reflected by the first reflective element 27, and then the lens 244 focuses the light beam to the end face of the output optical fiber 133, thereby coupling back to the optical fiber and outputting it, while the transmitted light passes through the lens 242 and is focused to the front end face of the first semiconductor optical amplifier 261. After the light beam passes through the first semiconductor optical amplifier 261, the light intensity is amplified. Since the light beam emitted from the rear end face of the first semiconductor optical amplifier 261 is a divergent light beam, the front end of the optical isolator 243 has a collimating lens, and the rear end of the optical isolator 243 has a focusing lens. The focusing lens focuses the light beam to the first optical fiber 132, thereby coupling it back to the optical fiber output.

[0038] The amplifier 2 and the FP filter 3 are connected by optical fiber to form a ring cavity, and under the action of two optical isolators, light can only pass through the optical amplifier in one direction, as shown in the figure, from left to right. At the beginning of the ring cavity startup, the light spontaneously radiated by the first semiconductor optical amplifier 261 passes through the optical isolator 243 and then reaches the FP filter 3. The narrow linewidth spectrum selected by the filter will pass through the filter, continue to be transmitted and emitted through the second optical fiber 131, and then pass through the optical isolator 241, the reflective element 251, the lens 242, the first semiconductor optical amplifier 261 and the optical isolator 243 in sequence. The first semiconductor optical amplifier 261 amplifies the light intensity of the spectrum, and the amplified light passes through the filter back to the optical amplifier to achieve re-amplification, and this cycle continues until the loss of the ring cavity is equal to the gain of the optical amplifier. The loss of the ring cavity includes the coupling loss of the light beam and the ratio of the emitted light. The filter is driven to scan the frequency selection, and the ring cavity can output a swept frequency optical signal. Embodiment 1 is a pre-output type, and its characteristic is that when the ring cavity is constructed, the output spectrum does not contain the spontaneous emission spectrum of the optical amplifier.

[0039] The second embodiment of the tunable laser:

[0040] Reference Figure 6 Based on the same principle as the first embodiment, the second embodiment of the tunable laser adopts a signal amplification post-output, that is, the signal input terminal 221, the optical isolator 243, the first semiconductor optical amplifier 261, the lens 242, the transflective element 251, the optical isolator 241 and the amplified output terminal 222 are arranged in sequence along the first amplified optical path, and then the transflective element 251 is located at the rear stage of the first semiconductor optical amplifier 261, and the transflective element 251, the first reflective element 27, the lens 244 and the signal output terminal 223 are arranged in sequence along the output optical path. After the signal is amplified, it is reflected by the transflective element 251 and the optical path is adjusted by the first reflective element 27, and then output from the signal output terminal 223, and the signal output terminal 223 and the amplified output terminal 222 of the second embodiment are located on the same side. Embodiment 2 is a post-output type, which is characterized in that when the ring cavity is built, the output spectrum contains the spontaneous emission spectrum of the optical amplifier.

[0041] The third embodiment of the tunable laser:

[0042] Reference Figure 7Based on the same principle as the first embodiment, the third embodiment of the tunable laser adopts signal amplification output. The amplifying device 2 is also provided with a second semiconductor optical amplifier 262, a lens 246 and a lens 245 in the output optical path, that is, the signal input end 221, the optical isolator 241, the transflective element 251, the lens 242, the first semiconductor optical amplifier 261, the optical isolator 243 and the amplified output end 222 are arranged in sequence along the first amplified optical path, and the transflective element 251, the first reflector 27, the lens 246, the second semiconductor optical amplifier 262, the optical isolator 245 and the signal output end 223 are arranged in sequence along the output optical path, so that after the signal is reflected and output by the transflective element 251, it can be output from the signal output end 223 after being amplified by the light intensity of the second semiconductor optical amplifier 262 again. Among them, the optical isolator 246 is an optical isolator with a focusing lens and a collimating lens, and the lens 246 adopts a focusing lens. Embodiment 3 is a pre-output type and is matched with a post-secondary amplification output.

[0043] As can be seen from the above, the filter input end is connected to the amplifier output end through the first optical fiber, and the filter output end is connected to the signal input end through the second optical fiber. The signal input end, the first semiconductor optical amplifier and the amplifier output end are arranged along the first amplifier optical path, so that the signal obtained by the FP optical filter device filtering process is input to the first semiconductor optical amplifier for amplification processing, and the transflective element is located in the front stage or the rear stage of the first semiconductor optical amplifier, so that the light before or after amplification is output through the signal output end. By arranging the necessary components of the tunable laser in an integrated manner, the cavity length of the ring cavity can be greatly reduced, thereby effectively realizing discrete single-frequency laser tuning and supporting higher-speed swept-frequency lasers. On the other hand, a shorter cavity length also improves the stability of the entire optical path. In the entire ring cavity, one-way transmission of light is achieved by connecting two optical isolators before and after the SOA chip.

[0044] The amplification device, the first optical fiber, the FP optical filter device and the second optical fiber form a closed annular cavity. The integrated arrangement of the necessary components can not only shorten the length of the annular cavity, but also ensure the stability of the entire annular cavity. The entire annular cavity, including the FP optical filter device, uses single-mode optical fiber. The FP optical filter device based on single-mode optical fiber has three important functions: first, it can obtain a low-loss, clean-line transmission spectrum; second, it can avoid the existence of irrelevant transverse modes in the annular cavity; finally, within the limits of the mechanical dynamics of the FP optical filter device and the longitudinal modes allowed by the annular cavity, it can achieve tuning of any wavelength and frequency scanning at any speed.

Claims

1. A tunable laser, characterized in that: It comprises an amplifying device and an FP optical filtering device, wherein the amplifying device is provided with an amplifying output end, a signal output end and a signal input end, and the FP optical filtering device is provided with a filtering input end and a filtering output end, wherein the filtering input end is connected to the amplifying output end through a first optical fiber, and the filtering output end is connected to the signal input end through a second optical fiber; The amplifying device is further provided with a first amplifying optical path, an output optical path, a transflective element and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifying output end are arranged along the first amplifying optical path, the transflective element is arranged on the first amplifying optical path, the transflective element is located at the front stage of the first semiconductor optical amplifier, and the transflective element and the signal output end are arranged along the output optical path; The amplifying device is further provided with a first reflecting member, which is arranged on the output optical path, located between the signal output end and the transflective member, and located on the reflecting side of the transflective member, the signal output end and the signal input end are located on the same side, and the signal input end and the amplified output end are located on opposite sides; The amplifying device is also provided with a bearing base and a semiconductor refrigerator, wherein the bearing base is provided on the first heat conduction end of the semiconductor refrigerator, and the first semiconductor optical amplifier is provided on the bearing base; The amplifying device further comprises a packaging shell, which encloses a sealed accommodating cavity, wherein the transflective element, the first semiconductor optical amplifier, the supporting base and the semiconductor refrigerator are arranged in the accommodating cavity, and the second heat conduction end of the semiconductor refrigerator is connected to the packaging shell.

2. The tunable laser according to claim 1, characterized in that: The amplifying device further comprises a first optical fiber base and a second optical fiber base, the output end of the first optical fiber is arranged on the first optical fiber base, and the input end of the second optical fiber base is arranged on the second optical fiber base.

3. The tunable laser according to claim 1, characterized in that: The amplifying device also sets a first optical isolator and a second optical isolator at both ends of the first semiconductor optical amplifier on the first amplifying optical path, the first optical isolator is located at the front end of the first semiconductor optical amplifier, and the second optical isolator is located at the rear end of the first semiconductor optical amplifier.

4. The tunable laser according to claim 3, characterized in that: The first optical isolator is an optical isolator with a collimating lens, and the second optical isolator is an optical isolator with a focusing lens and a collimating lens.

5. The tunable laser according to claim 1, characterized in that: The first optical fiber and / or the second optical fiber are single-mode optical fiber or polarization-maintaining optical fiber.

6. Tunable laser, characterized in that, It comprises an amplifying device and an FP optical filtering device, wherein the amplifying device is provided with an amplifying output end, a signal output end and a signal input end, and the FP optical filtering device is provided with a filtering input end and a filtering output end, wherein the filtering input end is connected to the amplifying output end through a first optical fiber, and the filtering output end is connected to the signal input end through a second optical fiber; The amplifying device is further provided with a first amplifying optical path, an output optical path, a transflective element and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifying output end are arranged along the first amplifying optical path, the transflective element is arranged on the first amplifying optical path, the transflective element is located at the front stage of the first semiconductor optical amplifier, and the transflective element and the signal output end are arranged along the output optical path; The amplifying device is further provided with a first reflecting member, the first reflecting member is provided on the output optical path, the first reflecting member is located between the signal output end and the transflective member, and the first reflecting member is located on the reflecting side of the transflective member; The signal output terminal and the amplifying output terminal are located on the same side, and the signal input terminal and the amplifying output terminal are located on the opposite side; The amplifying device is also provided with a bearing base and a semiconductor refrigerator, wherein the bearing base is provided on the first heat conduction end of the semiconductor refrigerator, and the first semiconductor optical amplifier is provided on the bearing base; The amplifying device further comprises a packaging shell, which encloses a sealed accommodating cavity, wherein the transflective element, the first semiconductor optical amplifier, the supporting base and the semiconductor refrigerator are arranged in the accommodating cavity, and the second heat conduction end of the semiconductor refrigerator is connected to the packaging shell.

7. The tunable laser according to claim 6, characterized in that: The amplifying device further comprises a first optical fiber base and a second optical fiber base, the output end of the first optical fiber is arranged on the first optical fiber base, and the input end of the second optical fiber base is arranged on the second optical fiber base.

8. The tunable laser according to claim 6, characterized in that: The amplifying device also sets a first optical isolator and a second optical isolator at both ends of the first semiconductor optical amplifier on the first amplifying optical path, the first optical isolator is located at the front end of the first semiconductor optical amplifier, and the second optical isolator is located at the rear end of the first semiconductor optical amplifier.

9. The tunable laser according to claim 8, characterized in that: The first optical isolator is an optical isolator with a collimating lens, and the second optical isolator is an optical isolator with a focusing lens and a collimating lens.

10. The tunable laser according to claim 6, characterized in that: The first optical fiber and / or the second optical fiber are single-mode optical fiber or polarization-maintaining optical fiber.

11. A tunable laser, characterized in that: It comprises an amplifying device and an FP optical filtering device, wherein the amplifying device is provided with an amplifying output end, a signal output end and a signal input end, and the FP optical filtering device is provided with a filtering input end and a filtering output end, wherein the filtering input end is connected to the amplifying output end through a first optical fiber, and the filtering output end is connected to the signal input end through a second optical fiber; The amplifying device is further provided with a first amplifying optical path, an output optical path, a transflective element and a first semiconductor optical amplifier, the signal input end, the first semiconductor optical amplifier and the amplifying output end are arranged along the first amplifying optical path, the transflective element is arranged on the first amplifying optical path, the transflective element is located at the rear stage of the first semiconductor optical amplifier, and the transflective element and the signal output end are arranged along the output optical path; The amplifying device is further provided with a first reflecting member, the first reflecting member is provided on the output optical path, the first reflecting member is located between the signal output end and the transflective member, and the first reflecting member is located on the reflecting side of the transflective member; The signal output terminal and the amplifying output terminal are located on the same side, and the signal input terminal and the amplifying output terminal are located on the opposite side; The amplifying device is further provided with a second semiconductor optical amplifier, which is arranged on the output optical path and located between the amplifying output end and the transflective element; The amplifying device is also provided with a bearing base and a semiconductor refrigerator, wherein the bearing base is provided on the first heat conduction end of the semiconductor refrigerator, and the first semiconductor optical amplifier is provided on the bearing base; The amplifying device further comprises a packaging shell, which encloses a sealed accommodating cavity, wherein the transflective element, the first semiconductor optical amplifier, the supporting base and the semiconductor refrigerator are arranged in the accommodating cavity, and the second heat conduction end of the semiconductor refrigerator is connected to the packaging shell.

12. The tunable laser according to claim 11, characterized in that: The amplifying device further comprises a first optical fiber base and a second optical fiber base, the output end of the first optical fiber is arranged on the first optical fiber base, and the input end of the second optical fiber base is arranged on the second optical fiber base.

13. The tunable laser according to claim 11, characterized in that: The amplifying device also sets a first optical isolator and a second optical isolator at both ends of the first semiconductor optical amplifier on the first amplifying optical path, the first optical isolator is located at the front end of the first semiconductor optical amplifier, and the second optical isolator is located at the rear end of the first semiconductor optical amplifier.

14. The tunable laser according to claim 13, characterized in that: The first optical isolator is an optical isolator with a collimating lens, and the second optical isolator is an optical isolator with a focusing lens and a collimating lens.

15. The tunable laser according to claim 11, characterized in that: The first optical fiber and / or the second optical fiber are single-mode optical fiber or polarization-maintaining optical fiber.

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