1064nm optical fiber amplifier for satellite space optical communication

Abstract

The invention relates to a 1064nm optical fiber amplifier for satellite space optical communication, and belongs to the technical field of satellite space optical communication. Comprising a first input end and a second input end which are backup for each other; the optical fiber coupler is input into the optical isolator; the first-stage optical fiber amplification part comprises a first-stage ytterbium ion optical fiber, a first-stage pump light coupler, a first-stage output isolator and a first-stage optical fiber coupler which are arranged in sequence; the second-stage optical fiber amplification part comprises a second-stage pump light coupler, a second-stage ytterbium ion optical fiber, a second-stage output isolator and a second-stage optical fiber coupler which are arranged in sequence; and the third-stage optical fiber amplification part comprises a third-stage pump light coupler, a third-stage ytterbium ion optical fiber and a pump light filter which are arranged in sequence, and the third-stage ytterbium ion optical fiber is provided with a spatial optical coupler. The light source has the advantages of being high in reliability, long in service life, resistant to radiation and the like, meets the requirement for low-power input signal light, and outputs signal power above 5W at the same time.

Description

Technical Field

[0001] The invention relates to a 1064nm optical fiber amplifier for satellite space optical communication, belonging to the technical field of satellite space optical communication. Background Art

[0002] The continuous development of satellite constellations and the need for networking have promoted the research and application of satellite space optical communication technology. With the increase in deep space exploration missions, the communication distance between the Earth and deep space probes is extremely long, and the signal attenuation is serious. Space optical communication, with its high directivity and high energy concentration, can maintain good performance in long-distance transmission.

[0003] Satellite space optical communications also face some challenges, one of which is high-power light sources and high-bitrate modulation technology. As the core component of the light source, the fiber amplifier must work without failure for more than 8 years, have a long life and high reliability, so these challenges need to be addressed urgently.

[0004] The fiber amplifier used in satellite space optical communication is in a vacuum, low pressure, and high-energy particle irradiation environment throughout its life cycle. At the same time, the heat consumption of the fiber amplifier is coupled into the satellite heat sink through the bottom surface. Since the low-orbit satellite orbits the earth once every 90 minutes, the temperature of the satellite heat sink cycles every 90 minutes. Depending on the orbit, the temperature difference of the satellite heat sink can reach 60°C when the environment is harsh.

[0005] On the basis of meeting the above working environment, the optical fiber amplifier for satellite space optical communication needs to output more than 5W signal power while meeting the low power (-8dBm) input signal light.

[0006] For example, Chinese patent announcement number CN210296856U discloses a single-frequency, single-mode, single-polarization fiber laser amplifier and laser system, which includes a seed source laser, a first-stage amplification structure, a polarization-maintaining mode matcher, an isolation filter structure, a second-stage amplification structure, and an output end. The first-stage amplification structure is used to perform single-stage double-pass gain amplification on the laser emitted by the seed source laser. The polarization-maintaining mode matcher is used to introduce the laser amplified by the first-stage amplification structure into the isolation filter structure to isolate and filter the laser. The second-stage amplification structure includes a first gain fiber, which is U-shaped and connects the isolation filter structure and the output end, and the second-stage amplification structure is used to perform single-pass gain amplification on the laser output by the isolation filter structure. However, it is still not satisfied with the above working environment. The fiber amplifier for satellite space optical communication needs to output more than 5W signal power while meeting the low-power (-8dBm) input signal light.

[0007] Therefore, in order to meet the indicators and working environment requirements of satellite space optical communications, it is necessary to propose a 1064nm optical fiber amplifier for satellite space optical communications. Summary of the invention

[0008] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a 1064nm optical fiber amplifier for satellite space optical communication, which has the characteristics of high reliability, long life, and radiation resistance, and can output a signal power of more than 5W while meeting the requirements of low-power (-8dBm) input signal light.

[0009] The 1064nm optical fiber amplifier for satellite space optical communication of the present invention comprises:

[0010] Input part: including the first input end and the second input end which are backup for each other; optical fiber coupler and input optical isolator;

[0011] The first-stage optical fiber amplification part includes a first-stage ytterbium ion optical fiber, a first-stage pump optical coupler, a first-stage output isolator and a first-stage optical fiber coupler which are arranged in sequence;

[0012] The second-stage optical fiber amplification part includes a second-stage pump optical coupler, a second-stage ytterbium ion optical fiber, a second-stage output isolator and a second-stage optical fiber coupler which are arranged in sequence;

[0013] The third-stage optical fiber amplification part comprises a third-stage pump optical coupler, a third-stage ytterbium ion optical fiber and a pump optical filter which are arranged in sequence, and a spatial optical coupler is installed on the third-stage ytterbium ion optical fiber.

[0014] The high-gain amplification of low input optical signals is achieved through the first-stage ytterbium ion fiber, and power amplification is achieved through the second-stage ytterbium ion fiber and the third-stage ytterbium ion fiber to meet the power required for satellite space optical communication. The pump laser backup and photodetector backup of the first-stage pump optical coupler, the second-stage pump optical coupler and the third-stage pump optical coupler are used to increase the trouble-free working time of the optical fiber amplifier. The return light monitoring of the first-stage optical fiber coupler and the second-stage optical fiber coupler protects the preceding optical fiber device, which ultimately greatly improves the long-life reliability of the optical fiber amplifier.

[0015] Preferably, the first-stage pump light coupler is connected to a polarization-maintaining combiner, the polarization-maintaining combiner is connected to two pump lasers, the pump lights output by the two pump lasers are coupled into an optical fiber through the polarization-maintaining combiner, and then coupled into the first-stage ytterbium ion optical fiber by the first-stage pump light coupler.

[0016] The first-stage pump optical coupler is connected to a polarization-maintaining beam combiner, and the polarization-maintaining beam combiner is connected to two pump lasers to realize backup of the pump lasers.

[0017] Preferably, the first-stage ytterbium ion optical fiber is a radiation-resistant optical fiber.

[0018] Preferably, the output power monitoring and return light monitoring of the output end of the first-stage output isolator are realized through a 2*2 first-stage optical fiber coupler, the monitoring end of the 2*2 first-stage optical fiber coupler is connected to a 1*2 first-stage optical fiber coupler 1 and a first-stage optical fiber coupler 2, the two output ends of the first-stage optical fiber coupler 1 and the first-stage optical fiber coupler 2 are respectively connected to a first-stage photodetector 1, a first-stage photodetector 2 and a first-stage photodetector 3, and a first-stage photodetector 4, the first-stage photodetector 1 and the first-stage photodetector 2, the first-stage photodetector 3 and the first-stage photodetector 4 are backed up for each other.

[0019] Here, the splitting ratio of the first-stage optical fiber coupler is 1:99, and the splitting ratio of the first-stage optical fiber coupler 1 and the first-stage optical fiber coupler 2 is 50:50.

[0020] Preferably, the second-stage pump optical coupler is connected to two pump lasers, which serve as backup for each other. The two pump lasers are multi-mode 915nm pump lasers.

[0021] Preferably, the output power monitoring and return light monitoring at the output end of the second-stage output isolator are realized through a 2*2 second-stage optical fiber coupler, the monitoring end of the 2*2 second-stage optical fiber coupler is connected to a 1*2 second-stage optical fiber coupler one and a second-stage optical fiber coupler two, the two output ends of the second-stage optical fiber coupler one and the second-stage optical fiber coupler two are respectively connected to a second-stage photodetector one, a second-stage photodetector two, a second-stage photodetector three, and a second-stage photodetector four, the second-stage photodetector one and the second-stage photodetector two, the second-stage photodetector three and the second-stage photodetector four are backed up for each other.

[0022] Preferably, the second-stage ytterbium ion optical fiber is a radiation-resistant double-clad optical fiber.

[0023] Preferably, the third-stage pump optical coupler is connected to six pump lasers, and the six pump lasers are divided into two groups of three, and the two groups of pump lasers serve as backup for each other. The six pump lasers are multi-mode 915nm pump lasers.

[0024] Preferably, the third-stage ytterbium ion optical fiber is a double-clad optical fiber with a core diameter of 10 μm and a cladding diameter of 125 μm.

[0025] Preferably, the spatial optical coupler is mounted on the third-stage ytterbium ion optical fiber, and two photodetectors are mounted on the spatial optical coupler. The two photodetectors monitor the brightness of the core light of the third-stage ytterbium ion optical fiber and serve as backup for each other.

[0026] Furthermore, the trouble-free working time of the optical fiber amplifier is increased by using a photodetector backup.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The 1064nm optical fiber amplifier for satellite space optical communication provided by the present invention realizes high-gain amplification of low input optical signals through the first-stage ytterbium ion optical fiber, realizes power amplification through the second and third-stage ytterbium ion optical fibers, meets the power required for satellite space optical communication, increases the trouble-free working time of the optical fiber amplifier through pump laser backup and photodetector backup, protects the front-stage optical fiber device through return light monitoring, and ultimately greatly improves the long-life reliability of the optical fiber amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic structural diagram of a 1064nm optical fiber amplifier for satellite space optical communication.

[0030] Wherein: 1, first input end; 2, second input end; 3, fiber coupler; 4, input optical isolator; 5, first-stage ytterbium ion fiber; 6, first-stage pump optical coupler; 61, polarization-maintaining combiner; 611, first-stage pump laser one; 612, first-stage pump laser two; 7, first-stage output isolator; 8, first-stage fiber coupler; 81, first-stage fiber coupler one; 82, first-stage fiber coupler two; 811, first-stage photodetector one; 812, first-stage photodetector two; 821, first-stage photodetector three; 822, first-stage photodetector four; 9, second-stage pump optical coupler; 91, second-stage pump laser one; 92, second-stage pump laser two; 10, second-stage ytterbium ion fiber; 11, second-stage Output isolator; 12, second-stage fiber coupler; 121, second-stage fiber coupler one; 122, second-stage fiber coupler two; 1211, second-stage photodetector one; 1212, second-stage photodetector two; 1221, second-stage photodetector three; 1222, second-stage photodetector four; 13, third-stage pump optical coupler; 131, third-stage pump laser one; 132, third-stage pump laser two; 133, third-stage pump laser three; 134, third-stage pump laser four; 135, third-stage pump laser five; 136, third-stage pump laser six; 14, third-stage ytterbium ion fiber; 15, pump light filter; 16, spatial optical coupler; 161, photodetector one; 162, photodetector two. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below.

[0032] Example 1

[0033] like Figure 1As shown, this embodiment 1 discloses a 1064nm optical fiber amplifier for satellite space optical communication, comprising:

[0034] Input part: including a first input terminal 1 and a second input terminal 2 which are backed up to each other; a fiber coupler 3 and an input optical isolator 4;

[0035] The first-stage optical fiber amplification part: the first-stage ytterbium ion optical fiber 5, the first-stage pump optical coupler 6, the first-stage output isolator 7 and the first-stage optical fiber coupler 8 are arranged in sequence;

[0036] The second-stage optical fiber amplification part: a second-stage pump optical coupler 9, a second-stage ytterbium ion optical fiber 10, a second-stage output isolator 11 and a second-stage optical fiber coupler 12 arranged in sequence;

[0037] The third-stage optical fiber amplification part includes a third-stage pump light coupler 13 , a third-stage ytterbium ion optical fiber 14 and a pump light filter 15 arranged in sequence, and a spatial optical coupler 16 is installed on the third-stage ytterbium ion optical fiber 14 .

[0038] High-gain amplification of low input optical signals is achieved through the first-stage ytterbium ion fiber 5, and power amplification is achieved through the second-stage ytterbium ion fiber 10 and the third-stage ytterbium ion fiber 14 to meet the power required for satellite space optical communication. The pump laser backup and photodetector backup of the first-stage pump optical coupler 6, the second-stage pump optical coupler 9 and the third-stage pump optical coupler 13 increase the trouble-free working time of the optical fiber amplifier, and the return light monitoring of the first-stage optical fiber coupler 8 and the second-stage optical fiber coupler 12 protects the front-stage optical fiber device, which ultimately greatly improves the long-life reliability of the optical fiber amplifier.

[0039] The first-stage pump light coupler 6 is connected to a polarization-maintaining combiner 61, and the polarization-maintaining combiner 61 is connected to two pump lasers. The pump lights output by the two pump lasers are coupled into an optical fiber through the polarization-maintaining combiner 61, and then coupled into the first-stage ytterbium ion optical fiber 5 by the first-stage pump light coupler 6.

[0040] Here, the two pump lasers are respectively the first-stage pump laser 1 611 and the first-stage pump laser 2 612. The polarization-maintaining combiner 61 is connected to the two first-stage pump lasers 1 611 and the first-stage pump laser 2 612 to realize the backup of the pump lasers. The pump light output by the first-stage pump laser 1 611 and the first-stage pump laser 2 612 is coupled into an optical fiber through the polarization-maintaining combiner 61, and then coupled into the first-stage ytterbium ion optical fiber 5 by the first-stage pump light coupler 6.

[0041] Specifically, the first-stage pump laser 1 611 and the first-stage pump laser 2 612 are wide-temperature polarization-maintaining 980nm pump lasers.

[0042] The first-stage ytterbium ion optical fiber 5 is a radiation-resistant optical fiber.

[0043] The output power monitoring and return light monitoring of the output end of the first-stage output isolator 7 are realized through the 2*2 first-stage optical fiber coupler 8. The monitoring end of the 2*2 first-stage optical fiber coupler 8 is connected to the 1*2 first-stage optical fiber coupler 1 81 and the first-stage optical fiber coupler 2 82. The two output ends of the first-stage optical fiber coupler 1 81 and the first-stage optical fiber coupler 2 82 are respectively connected to the first-stage photodetector 1 811, the first-stage photodetector 2 812 and the first-stage photodetector 3 821, the first-stage photodetector 4 822. The first-stage photodetector 1 811 and the first-stage photodetector 2 812, the first-stage photodetector 3 821 and the first-stage photodetector 4 822 are backed up for each other.

[0044] Here, the splitting ratio of the first-stage optical fiber coupler 8 is 1:99, and the splitting ratios of the first-stage optical fiber coupler 1 81 and the first-stage optical fiber coupler 2 82 are 50:50.

[0045] The second-stage pump optical coupler 9 is connected to two pump lasers, which serve as backup for each other. The two pump lasers are multi-mode 915nm pump lasers.

[0046] Here, the two pump lasers are the second-stage pump laser 1 91 and the second-stage pump laser 2 92. The second-stage pump optical coupler 9 is connected to the second-stage pump laser 1 91 and the second-stage pump laser 2 92 to couple the pump laser into the second-stage ytterbium ion optical fiber 10.

[0047] The output power monitoring and return light monitoring of the output end of the second-stage output isolator 11 are realized through a 2*2 second-stage optical fiber coupler 12. The monitoring end of the 2*2 second-stage optical fiber coupler 12 is connected to a 1*2 second-stage optical fiber coupler 1121 and a second-stage optical fiber coupler 122. The two output ends of the second-stage optical fiber coupler 1121 and the second-stage optical fiber coupler 122 are respectively connected to a second-stage photodetector 1211, a second-stage photodetector 2 1212, a second-stage photodetector 3 1221, and a second-stage photodetector 4 1222. The second-stage photodetector 1211 and the second-stage photodetector 2 1212, the second-stage photodetector 3 1221 and the second-stage photodetector 4 1222 are backed up for each other.

[0048] The second-stage ytterbium ion optical fiber 10 is a radiation-resistant double-clad optical fiber.

[0049] The third-stage pump optical coupler 13 is connected to six pump lasers, and the six pump lasers are divided into two groups of three, and the two groups of pump lasers serve as backup for each other. The six pump lasers are multi-mode 915nm pump lasers.

[0050] Here, the six pump lasers are respectively a third-stage pump laser 1 131, a third-stage pump laser 2 132, a third-stage pump laser 3 133, a third-stage pump laser 4 134, a third-stage pump laser 5 135, and a third-stage pump laser 6 136. The third-stage pump optical coupler 13 is connected to the six pump lasers (the third-stage pump laser 1 131, the third-stage pump laser 2 132, the third-stage pump laser 3 133, the third-stage pump laser 4 134, the third-stage pump laser 5 135, and the third-stage pump laser 6 136) to couple the pump laser into the third-stage ytterbium ion fiber 14. The six pump lasers are divided into two groups of three, the third-stage pump laser one 131, the third-stage pump laser two 132, and the third-stage pump laser three 133 are one group, and the third-stage pump laser four 134, the third-stage pump laser five 135, and the third-stage pump laser six 136 are another group, which backup each other.

[0051] The third-stage ytterbium ion optical fiber 14 is a double-clad optical fiber with a core diameter of 10 μm and a cladding diameter of 125 μm.

[0052] The pump light filter 15 is prepared by microstructurally processing the cladding of the third-stage ytterbium ion optical fiber 14 , and is disposed on the third-stage ytterbium ion optical fiber 14 .

[0053] The spatial optical coupler 16 is installed on the third-stage ytterbium ion optical fiber 14 . Two photodetectors are installed on the spatial optical coupler 16 . The two photodetectors monitor the core light brightness of the third-stage ytterbium ion optical fiber 14 and serve as backup for each other.

[0054] Here, the two photodetectors are photodetector 1 161 and photodetector 2 162 , which monitor the core light brightness of the third-stage ytterbium ion optical fiber 14 and serve as backup for each other.

[0055] In spatial layout, the second-stage pump laser 1 91 and the second-stage pump laser 2 92 are regarded as one body, the third-stage pump laser 1 131 and the third-stage pump laser 4 134 are regarded as one body, the third-stage pump laser 2 132 and the third-stage pump laser 5 135 are regarded as one body, the third-stage pump laser 3 133 and the third-stage pump laser 6 136 are regarded as one body, and the four groups are evenly distributed on the bottom surface.

[0056] The second-stage ytterbium ion optical fiber 10 and the third-stage ytterbium ion optical fiber 14 are bonded to the bottom surface of the optical amplifier by means of thermal conductive adhesive.

[0057] All optical fiber devices used are industrial-grade devices that have been irradiated and vacuum-verified.

[0058] In order to explain the technical solution of the present invention more clearly, the following is a detailed description of its working process:

[0059] Regarding the first stage amplification, in order to meet the input optical power as low as -8dBm, the first stage ytterbium ion fiber 5 uses 6 meters and provides at least 25dB of gain. The rated operating current of the first stage pump laser 1 611 and the first stage pump laser 2 612 is 1A, and the output optical power is 600mW; according to the derating requirements, the first stage pump laser 1 611 and the first stage pump laser 2 612 are in operation with an operating current of 500mW. The isolation of the 980nm channel of the first stage pump optical coupler 6 to the 1064nm wavelength is ≥20dB. The isolation of the polarization-maintaining combiner 61 to the 1064nm wavelength is ≥20dB.

[0060] Regarding the second stage amplification, the second stage ytterbium ion fiber 10 has a core diameter of 10 μm and a length of 8 meters. The second stage pump laser 1 91 and the second stage pump laser 2 92 are 10W, 915nm multi-mode pump lasers. The second stage output isolator 11 has a rated working power of 3W.

[0061] Regarding the third-stage amplification, the third-stage ytterbium ion fiber 10 has a core diameter of 10 μm and a length of 4 meters. The third-stage pump optical coupler 13 is a (6+1)*1 pump signal combiner with the ability of forward pumping and reverse pumping. A microstructure is machined on the cladding of the third-stage ytterbium ion fiber 10 using a femtosecond laser to make a pump light filter 15.

[0062] The present invention, through structural optimization and improvement, simultaneously meets the requirements of wide operating temperature, low input signal optical power, and high output signal optical power in a vacuum irradiation environment.

[0063] It should be noted that the optical fiber device in the present invention can be a polarization-maintaining optical fiber device or a non-polarization-maintaining optical fiber device, which correspond to a polarization-maintaining optical fiber amplifier and a non-polarization-maintaining optical fiber amplifier respectively.

[0064] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not restrictive. Therefore, the present invention is not limited to the embodiments described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A 1064nm optical fiber amplifier for satellite space optical communication, characterized in that: include: The input part comprises a first input end (1) and a second input end (2) which serve as backup for each other; an optical fiber coupler (3) and an input optical isolator (4); The first-stage optical fiber amplification part comprises a first-stage ytterbium ion optical fiber (5), a first-stage pump optical coupler (6), a first-stage output isolator (7) and a first-stage optical fiber coupler (8) arranged in sequence; The second-stage optical fiber amplification part comprises a second-stage pump optical coupler (9), a second-stage ytterbium ion optical fiber (10), a second-stage output isolator (11) and a second-stage optical fiber coupler (12) which are arranged in sequence; The third-stage optical fiber amplification part comprises a third-stage pump light coupler (13), a third-stage ytterbium ion optical fiber (14) and a pump light filter (15) which are arranged in sequence, and a spatial optical coupler (16) is installed on the third-stage ytterbium ion optical fiber (14).

2. A 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The first-stage pump light coupler (6) is connected to a polarization-maintaining beam combiner (61), and the polarization-maintaining beam combiner (61) is connected to two pump lasers. Pump light output by the two pump lasers is coupled into an optical fiber through the polarization-maintaining beam combiner (61), and then coupled into the first-stage ytterbium ion optical fiber (5) through the first-stage pump light coupler (6).

3. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The first-stage ytterbium ion optical fiber (5) is a radiation-resistant optical fiber.

4. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The output power monitoring and return light monitoring at the output end of the first-stage output isolator (7) are realized through the first-stage optical fiber coupler (8); the monitoring end of the first-stage optical fiber coupler (8) is connected to the first-stage optical fiber coupler 1 (81) and the first-stage optical fiber coupler 2 (82); the output end of the first-stage optical fiber coupler 1 (81) is connected to the first-stage photoelectric detector 1 (811) and the first-stage photoelectric detector 2 (812); the output end of the first-stage optical fiber coupler 2 (82) is connected to the first-stage photoelectric detector 3 (821) and the first-stage photoelectric detector 4 (822); the first-stage photoelectric detector 1 (811) and the first-stage photoelectric detector 2 (812), the first-stage photoelectric detector 3 (821) and the first-stage photoelectric detector 4 (822) are backed up for each other.

5. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The second-stage pump optical coupler (9) is connected to two pump lasers, and the two pump lasers serve as backup for each other.

6. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The output power monitoring and return light monitoring at the output end of the second-stage output isolator (11) are realized through the second-stage optical fiber coupler (12); the monitoring end of the second-stage optical fiber coupler (12) is connected to the second-stage optical fiber coupler 1 (121) and the second-stage optical fiber coupler 2 (122); the output end of the second-stage optical fiber coupler 1 (121) is connected to the second-stage photoelectric detector 1 (1211) and the second-stage photoelectric detector 2 (1212); the output end of the second-stage optical fiber coupler 2 (1222) is connected to the second-stage photoelectric detector 3 (1221) and the second-stage photoelectric detector 4 (1222); the second-stage photoelectric detector 1 (1211) and the second-stage photoelectric detector 2 (1212), the second-stage photoelectric detector 3 (1221) and the second-stage photoelectric detector 4 (1222) are backed up for each other.

7. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The second-stage ytterbium ion optical fiber (10) is a radiation-resistant double-clad optical fiber.

8. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The third-stage pump optical coupler (13) is connected to six pump lasers, and the six pump lasers are divided into two groups of three, and the two groups of pump lasers serve as backup for each other.

9. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The third-level ytterbium ion optical fiber (14) is a double-clad optical fiber with a core diameter of 10 μm and a cladding diameter of 125 μm.

10. The 1064nm optical fiber amplifier for satellite space optical communication according to claim 1, characterized in that: The spatial optical coupler (16) is mounted on the third-level ytterbium ion optical fiber (14). Two photoelectric detectors are mounted on the spatial optical coupler (16). The two photoelectric detectors monitor the core light brightness of the third-level ytterbium ion optical fiber (14) and serve as backup for each other.

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