High-reliability fiber laser

Abstract

The utility model relates to a high-reliability fiber laser. Comprising a signal light chip, a temperature control device, a first collimation coupling device, a first isolator, a first light reflection device, a first collimator, a gain fiber, a second collimator, a second light reflection device, a pump light chip, a second collimation coupling device, a third light reflection device, a second isolator, a light splitting device, a photoelectric detector, a fourth light reflection device and a third collimator. A housing and a cover plate. According to the utility model, active devices and most passive devices are packaged in the same shell, and a specific optical path structure is adopted, so that the gain optical fiber and the sealed cavity are not connected, the sealing performance in the shell can be effectively ensured, the reliability is high, and meanwhile, the structure is compact, and the number of optical fiber connection points is small.

Description

Technical Field

[0001] The utility model relates to the technical field of lidar, and particularly relates to a highly reliable fiber laser. Background Art

[0002] With the continuous development of fiber laser technology, its application fields are becoming wider and wider. In recent years, it has been widely used especially in the technical field of lidar. The fiber lasers of ordinary lidar light sources usually connect all devices (such as a pigtailed seed source, a pigtailed pump source, a beam combiner, an isolator, and gain fiber) together by means of fiber fusion. There are problems such as large volume and many fiber connection points. The large variety of devices also results in relatively high manufacturing costs for mass production. Additionally, since the output fiber needs to extend out of the encapsulated housing, the sealing performance of the housing is poor, thus reducing the reliability of the product. Summary of the Invention

[0003] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a highly reliable fiber laser.

[0004] To achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A highly reliable fiber laser includes a signal light chip, a temperature control device, a first collimating and coupling device, a first isolator, a first light reflection device, a first collimator, gain fiber, a second collimator, a second light reflection device, a pump light chip, a second collimating and coupling device, a third light reflection device, a second isolator, a beam splitting device, a photodetector, a fourth light reflection device, a third collimator, a housing, and a cover plate;

[0006] The cover plate is connected to the housing, and a sealed cavity is formed between the two;

[0007] The signal light chip is installed on the temperature control device and is used for emitting signal light;

[0008] The temperature control device is installed at the inner bottom of the housing and is used for controlling the temperature of the signal light chip;

[0009] The first collimating and coupling device is installed at the inner bottom of the housing and is used for collimating the signal light and coupling the signal light into the first isolator;

[0010] The first isolator is installed at the inner bottom of the housing and is used for transmitting the collimated signal light and isolating the light transmitted in the reverse direction;

[0011] The first light reflection device is composed of a first lower reflector installed at the inner bottom of the housing and a first upper reflector installed on the outer side of the cover plate, and is used for reflecting the collimated signal light passing through the first isolator from the inside of the housing to the outside of the housing;

[0012] The first collimator is installed on the outer side of the cover plate, and is used for receiving the signal light passing through the first light reflection device and transmitting it into the core of the gain fiber;

[0013] The gain fiber is wound outside the cavity and connected to the first collimator and the second collimator, and is used for absorbing pump light and amplifying the signal light;

[0014] The pump light chip is installed at the bottom inside the housing, and is used for emitting pump light;

[0015] The second collimation coupling device is installed at the bottom inside the housing, and is used for collimating the pump light and coupling the pump light to the second light reflection device;

[0016] The second light reflection device is composed of a second lower reflector installed at the bottom inside the housing and a second upper reflector installed on the outer side of the cover plate, and is used for reflecting the collimated pump light from the inside of the housing to the outside of the housing;

[0017] The second collimator is installed on the outer side of the cover plate, and is used for receiving the pump light passing through the second light reflection device and transmitting it into the inner cladding of the gain fiber;

[0018] The third light reflection device is composed of a third lower reflector installed at the bottom inside the housing and a third upper reflector installed on the outer side of the cover plate, and the third light reflection device is used for reflecting the amplified signal light from the outside of the housing to the inside of the housing;

[0019] The second isolator is installed at the bottom inside the housing, and is used for transmitting the amplified signal light and isolating the light transmitted in the reverse direction;

[0020] The beam splitting device is installed at the bottom inside the housing, and is used for splitting the amplified signal light in a required proportion. Most of the signal light is transmitted to the fourth light reflection device, and a small part of the signal light is transmitted to the photodetector;

[0021] The photodetector is used for detecting the signal light and converting the optical signal into an electrical signal;

[0022] The fourth light reflection device is composed of a fourth lower reflector installed at the bottom inside the housing and a fourth upper reflector installed on the outer side of the cover plate, and is used for reflecting most of the signal light transmitted by the beam splitting device from the inside of the housing to the outside of the housing;

[0023] The third collimator is installed on the outer side of the cover plate, and is used for receiving the signal light passing through the fourth light reflection device and outputting the amplified signal light;

[0024] The side wall of the housing is provided with pins that are disconnected from the side wall. The pins are used for connecting the signal light chip, the temperature control device, the pump light chip, and the photodetector to be connected to an external driver. The housing is used for installing the above devices and has a heat dissipation function;

[0025] The cover plate is made of a transparent material and is used to transmit the signal light and the pump light.

[0026] Furthermore, the first collimating and coupling device and the second collimating and coupling device are composed of one or more than two lenses, and the lenses are spherical, aspherical or cylindrical.

[0027] Furthermore, the first isolator and the second isolator are single-stage or multi-stage isolators.

[0028] Furthermore, the first upper reflector, the first lower reflector, the second upper reflector, the second lower reflector, the fourth upper reflector, and the fourth lower reflector are plane reflectors or triangular prisms; the third upper reflector and the third lower reflector are plane reflectors, triangular prisms or dichroic mirrors.

[0029] Furthermore, the optical fibers of the first collimator, the second collimator, and the third collimator are single-clad or double-clad optical fibers.

[0030] Furthermore, the pin electrical connection methods of the signal light chip, the pump light chip, and the photodetector adopt ultrasonic aluminum wire thermocompression welding, ultrasonic gold wire ball bonding or thermo-ultrasonic gold wire wedge bonding.

[0031] Furthermore, the material of the housing is ceramic.

[0032] Furthermore, the material of the cover plate is glass.

[0033] Furthermore, antireflection films for the pump light and the signal light are coated on both the upper and lower surfaces of the cover plate.

[0034] Furthermore, the gain fiber is single-clad or double-clad optical fiber, and the doped ions are erbium ions or co-doped erbium and ytterbium ions.

[0035] Adopting the above technical solutions, the beneficial effects of the present utility model are as follows:

[0036] 1. In the present utility model, the active devices and most of the passive devices are encapsulated in the same housing, and a specific optical path structure is adopted, so that there is no connection relationship between the gain fiber and the sealed cavity, the sealing performance inside the housing can be effectively guaranteed, the reliability is high, and at the same time, it has the advantages of compact structure and few fiber connection points;

[0037] 2. The housing and the cover plate enclose a sealed cavity, and the signal light chip and the pump light chip are located inside the cavity, preventing condensation on the chip end face at low temperature and causing chip failure, effectively reducing the failure rate of the fiber laser and improving the reliability. Description of the Drawings

[0038] The following further elaborates on the present utility model in conjunction with the accompanying drawings and specific embodiments:

[0039] Figure 1 It is the top view of the embodiment of the present utility model;

[0040] Figure 2 It is Figure 1 the schematic diagram of the A-A section and the optical transmission route of

[0041] Figure 3 It is Figure 1 the schematic diagram of the B-B section and the optical transmission route of

[0042] Figure 4 It is the side view of the first optical reflection device of the embodiment of the present utility model;

[0043] Figure 5 It is the side view and the perspective view of the second optical reflection device of the embodiment of the present utility model;

[0044] Figure 6 It is the side view of the third optical reflection device of the embodiment of the present utility model;

[0045] Figure 7 It is the side view of the fourth optical reflection device of the embodiment of the present utility model;

[0046] In the figure: 1, temperature control device; 2, signal optical chip; 3, first collimating and coupling device; 4, first isolator; 5, first optical reflection device; 501, first upper reflecting mirror; 502, first lower reflecting mirror; 6, first collimator; 7, gain fiber; 8, second collimator; 9, second optical reflection device; 901, second upper reflecting mirror; 902, second lower reflecting mirror; 10, pump optical chip; 11, second collimating and coupling device; 12, third optical reflection device; 1201, third upper reflecting mirror; 1202, third lower reflecting mirror; 13, second isolator; 14, beam splitting device; 15, photodetector; 16, fourth optical reflection device; 1601, fourth upper reflecting mirror; 1602, fourth lower reflecting mirror; 17, third collimator; 18, housing; 19, cover plate. Specific Embodiments

[0047] Please refer to Figures 1 to 7 , which is a highly reliable fiber laser of the present utility model. The structure of this embodiment includes: signal optical chip 2, temperature control device 1, first collimating and coupling device 3, first isolator 4, first optical reflection device 5, first collimator 6, gain fiber 7, second collimator 8, second optical reflection device 9, pump optical chip 10, second collimating and coupling device 11, third optical reflection device 12, second isolator 13, beam splitting device 14, photodetector 15, fourth optical reflection device 16, third collimator 17, housing 18 and cover plate 19.

[0048] The housing 18 of the cassette structure and the cover plate 19 fastened to the housing 18; a sealed cavity is enclosed between the housing 18 and the cover plate 19, and pins disconnected from the side wall are provided on the side wall of the housing 18. The pins are used to connect the signal optical chip 2, the temperature control device 1, the pump optical chip 10, and the photodetector 15 to be connected to an external driver. The housing 18 is used to mount the above devices and has a heat dissipation function. The pin electrical connection methods of the signal optical chip 2, the pump optical chip 10, and the photodetector 15 can adopt ultrasonic aluminum wire thermocompression welding, ultrasonic gold wire ball welding, or thermosonic gold wire wedge welding.

[0049] The material of the housing 18 is ceramic, such as aluminum nitride, alumina, beryllium oxide, or silicon carbide, and its shape is a cuboid, a cylinder, or any other regular or irregular shape. The cover plate 19 is made of a transparent material, and antireflection films for pump light and signal light are coated on both the upper and lower surfaces of the cover plate 19 for sealing the housing and transmitting the signal light and the pump light. The material of the cover plate 19 can be glass, such as K9, BK7, or D263T, and its coefficient of thermal expansion should be close to that of the housing 18.

[0050] The first collimating and coupling device 3 and the second collimating and coupling device 11 are composed of one or more than two lenses, and the lenses are spherical, aspherical, or cylindrical.

[0051] The first isolator 3 and the second isolator 13 are single-stage or multi-stage isolators.

[0052] The optical fibers of the first collimator 6, the second collimator 8, and the third collimator 17 are single-clad or double-clad optical fibers.

[0053] The first light reflection device 5 is composed of a first upper reflecting mirror 501 and a first lower reflecting mirror 502;

[0054] The second light reflection device 9 is composed of a second upper reflecting mirror 901 and a second lower reflecting mirror 902;

[0055] The third light reflection device 12 is composed of a third upper reflecting mirror 1201 and a third lower reflecting mirror 1202;

[0056] The fourth light reflection device 16 is composed of a first upper reflecting mirror 1601 and a fourth lower reflecting mirror 1602.

[0057] Among them, the temperature control device 1, the signal optical chip 2, the first collimating and coupling device 3, the first isolator 4, the first lower reflecting mirror 502, the second lower reflecting mirror 902, the pump optical chip 10, the second collimating and coupling device 11, the third lower reflecting mirror 1202, the second isolator 13, the beam splitting device 14, the photodetector 15, and the fourth lower reflecting mirror 1602 are located in the cavity.

[0058] The first upper reflector 501, the first collimator 6, the gain fiber 7, the second collimator 8, the second upper reflector 901, the third upper reflector 1201, the fourth upper reflector 1601, and the third collimator 17 are located outside the cavity.

[0059] The temperature control device 1 is a semiconductor refrigeration chip, fixed to the inner bottom of the housing 18, used to control the temperature of the signal light chip 2, and its pins are connected to the corresponding pins on the side wall of the housing 18;

[0060] The signal light chip 2 is fixed on the temperature control device 1, and its pins are connected to the corresponding pins on the side wall of the housing 18. The signal light chip 2 emits signal light with a wavelength of 1535 nm;

[0061] The first collimation coupling device 3 is fixed to the inner bottom of the housing 18, collimates the signal light and couples the signal light into the first isolator 4;

[0062] The first isolator 4 is fixed to the inner bottom of the housing 18, used to transmit the collimated signal light and isolate the light transmitted in the reverse direction;

[0063] The first lower reflector 502 is a triangular prism. One of its right-angle faces is fixed to the inner bottom of the housing 18. Its inclined surface is coated with a high-reflection film for signal light and faces the collimated signal light, changing the transmission direction of the signal light from horizontal to vertically upward and transmitting it through the upper cover plate 19;

[0064] The first upper reflector 501 is a triangular prism. One of its right-angle faces is fixed to the cover plate 19 and faces the first lower reflector 502. The signal light transmitted through the cover plate 19 reaches the inclined surface of the first upper reflector 501 after passing through this right-angle face. The (inclined surface) reflection surface is coated with a high-reflection film for signal light, and the signal light is reflected and transmitted through the other right-angle face. Both right-angle faces of the first upper reflector 501 are coated with an anti-reflection film for signal light;

[0065] The first collimator 6 is fixed to the outside of the cover plate 19, used to receive the signal light passing through the first upper reflector 501 and transmit the signal light into the core of the gain fiber 7.

[0066] The gain fiber 7 is coiled outside the cavity and connected to the first collimator 6 and the second collimator 8, used to absorb the pump light and amplify the signal light;

[0067] The pump light chip 10 is fixed to the inner bottom of the housing 18, and its pins are connected to the corresponding pins on the side wall of the housing 18. The pump light chip 10 emits pump light with a wavelength of 900 nm to 1000 nm;

[0068] The second collimation coupling device 11 is fixed to the inner bottom of the housing 18, collimates the pump light;

[0069] The second lower reflector 902 is a triangular prism. One of its right-angle faces is fixed to the inner bottom of the housing 18. Its inclined surface is coated with a high-reflection film for pump light and faces the collimated pump light. The pump light is transmitted from the horizontal direction to the vertical direction and passes through the upper cover plate 19 above;

[0070] The second upper reflector 901 is a triangular prism. One of its right-angle faces is fixed to the outer side of the cover plate 19 and faces the second lower reflector 902. The pump light passing through the cover plate 19 reaches the inclined surface of the second upper reflector 901 after passing through this right-angle face. The (inclined surface) reflecting surface is coated with a high-reflection film for pump light and an antireflection film for signal light. The pump light is reflected and passes through another right-angle face. Both right-angle faces of the second upper reflector 901 are coated with antireflection films for pump light and signal light;

[0071] The second collimator 8 is fixed to the outer side of the cover plate 19 and is used to receive the pump light passing through the second upper reflector 901 and transmit the pump light into the inner cladding of the gain fiber 7.

[0072] The gain fiber 7 is an erbium-ytterbium co-doped double-clad fiber, wound outside the cavity, absorbs the pump light and amplifies the signal light; the amplified signal light passes through the inclined surface of the second upper reflector 901 after passing through the second collimator 8;

[0073] The third upper reflector 1201 is a triangular prism. Both right-angle faces are coated with antireflection films for signal light, and the inclined surface is coated with a high-reflection film for signal light. One of its right-angle faces is fixed to the outer side of the cover plate 19, and the other right-angle face faces the second upper reflector 901 and is used to reflect the amplified signal light through the cover plate 19;

[0074] The third lower reflector 1202 is a triangular prism. The inclined surface is coated with a high-reflection film for signal light. One of its right-angle faces is fixed to the inner bottom of the housing 18 and is used to reflect the signal light passing through the cover plate 19 to make it horizontally transmitted;

[0075] The second isolator 13 is fixed to the inner bottom of the housing 18 and is used to transmit the amplified signal light and isolate the light transmitted in the reverse direction.

[0076] The beam splitting device 14 is a partially reflecting lens, fixed to the inner bottom of the housing 18, at a 45-degree angle to the signal light transmission direction, and is used to split the amplified signal light in a required proportion. Most of the signal light is transmitted to the fourth light reflection device 16, and a small part of the signal light is reflected to reach the photodetector 15 fixed to the inner bottom of the housing 18. The photodetector 15 generates an electrical signal, and the pins of the photodetector 15 are connected to the corresponding pins on the side wall of the housing 18.

[0077] The photodetector 15 is used to detect the signal light and convert the optical signal into an electrical signal.

[0078] The fourth lower reflector 1602 is a triangular prism, with a high-reflection film for signal light plated on its inclined surface. One of its right-angle surfaces is fixed to the inner bottom of the housing 18, and is used to reflect most of the signal light transmitted by the beam splitting device 14, making it vertically upward transmitted to the cover plate 19;

[0079] The fourth upper reflector 1601 is a triangular prism. One of its right-angle surfaces is fixed to the cover plate 19 and faces the fourth lower reflector 1602. The signal light passing through the cover plate 19 reaches the inclined surface of the fourth upper reflector 1601 after passing through this right-angle surface. The (inclined surface) reflecting surface is plated with a high-reflection film for signal light, and the signal light is reflected and transmitted through the other right-angle surface. Both right-angle surfaces of the fourth upper reflector 1601 are plated with an antireflection film for signal light;

[0080] The third collimator 17 is fixed to the outer side of the cover plate 19, and is used to receive the signal light passing through the fourth upper reflector 1601. The finally amplified signal light is output from the optical fiber of the third collimator 17.

[0081] A packaging method for a highly reliable fiber laser corresponding to the embodiment includes the following steps:

[0082] Step 1: Fix the signal light chip 2 on the temperature control device 1 by AuSn soldering;

[0083] Step 2: Fix the temperature control device 1 on the inner bottom of the housing 18 by AuSn soldering or by glue;

[0084] Step 3: Connect the leads of the temperature control device 1 to the corresponding pins by soldering, and connect the positive and negative electrodes of the signal light chip 2 to the positive and negative electrode pins respectively with gold wires;

[0085] Step 4: In the state where the signal chip 2 emits signals, fix the first collimation coupling device 3, the first isolator 4, and the first lower reflector 502 on the inner bottom of the housing in sequence with glue;

[0086] Step 5: Fix the pump light chip 10 on the inner bottom of the housing 18 by AuSn soldering;

[0087] Step 6: Connect the positive and negative electrodes of the pump light chip 10 to the positive and negative electrode pins respectively with gold wires;

[0088] Step 7: In the state where the pump light chip 10 emits signals, fix the second collimation coupling device 11 and the second lower reflector 902 on the inner bottom of the housing 18 in sequence with glue;

[0089] Step 8: Fix the third lower reflector 1202, the second isolator 13, the beam splitting device 14, the photodetector 15, and the fourth lower reflector 1602 on the inner bottom of the housing 18 in sequence with glue;

[0090] Step 9: Connect the positive and negative electrodes of the photodetector 15 to the positive and negative electrode pins correspondingly with gold wires;

[0091] Step 10: Fix the cover plate 19 on the upper edge of the housing 18 with glue. At the same time, fill the inside of the housing 18 with dry air to make the inside of the housing 18 in a sealed state with the outside;

[0092] Step 11: Fix the first upper reflector 501, the first collimator 6, the second upper reflector 901, the second collimator 8, the third upper reflector 1201, the fourth upper reflector 1601, and the third collimator 17 on the outside of the cover plate 19 with glue in sequence;

[0093] Step 12: Connect the gain fiber 7 to the fibers of the first collimator 6 and the second collimator 8 by fusion splicing.

[0094] In addition, in the above packaging method, corresponding template images are respectively engraved at the installation positions of the active devices and passive devices on the housing 18 and the cover plate 19. The template images are captured by a camera to identify image features, and the captured images are processed by a processor for real-time positioning, which is relatively easy to realize the orderly automatic assembly of the active devices and passive devices on the housing and the cover plate. With the increase in demand, automatic assembly can greatly reduce the manufacturing cost of mass production.

[0095] The specific implementation manners of the present invention have been described above. However, those skilled in the art should understand that this is only an example. Without departing from the principle and essence of the present invention, those skilled in the art can make various changes or modifications to this implementation manner, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A high reliability fiber laser, characterized in that: It includes a signal light chip, a temperature control device, a first collimation coupling device, a first isolator, a first light reflecting device, a first collimator, a gain optical fiber, a second collimator, a second light reflecting device, a pump light chip, a second collimation coupling device, a third light reflecting device, a second isolator, a light splitting device, a photodetector, a fourth light reflecting device, a third collimator, a housing and a cover plate; The cover plate is connected to the shell and the two are enclosed to form a sealed cavity; The signal light chip is installed on the temperature control device and is used to emit signal light; The temperature control device is installed at the bottom of the inner side of the housing and is used to control the temperature of the signal light chip; The first collimation coupling device is installed at the inner bottom of the housing, and is used to collimate the signal light and couple the signal light to the first isolator; The first isolator is installed at the bottom of the inner side of the housing, and is used to transmit the collimated signal light and isolate the reversely transmitted light; The first light reflecting device is composed of a first lower reflecting mirror installed on the inner bottom of the housing and a first upper reflecting mirror installed on the outer side of the cover plate, and is used to reflect the collimated signal light passing through the first isolator from the inside of the housing to the outside of the housing; The first collimator is mounted on the outer side of the cover plate, and is used to receive the signal light passing through the first light reflecting device and transmit it to the core of the gain optical fiber; The gain optical fiber is coiled outside the cavity and connected to the first collimator and the second collimator, and is used to absorb the pump light and amplify the signal light; The pump light chip is installed at the inner bottom of the housing and is used to emit pump light; The second collimating coupling device is installed at the inner bottom of the housing, and is used to collimate the pump light and couple the pump light to the second light reflecting device; The second light reflecting device is composed of a second lower reflecting mirror installed on the inner bottom of the housing and a second upper reflecting mirror installed on the outer side of the cover plate, and is used to reflect the collimated pump light from the inside of the housing to the outside of the housing; The second collimator is mounted on the outer side of the cover plate, and is used to receive the pump light passing through the second light reflecting device, and transmit it to the inner cladding of the gain optical fiber; The third light reflecting device is composed of a third lower reflecting mirror installed on the bottom of the inner side of the housing and a third upper reflecting mirror installed on the outer side of the cover plate, and the third light reflecting device is used to reflect the amplified signal light from the outside of the housing to the inside of the housing; The second isolator is installed at the bottom of the inner side of the housing, and is used to transmit the amplified signal light and isolate the reversely transmitted light; The light splitting device is installed at the bottom of the inner side of the housing, and is used to split the amplified signal light according to the required proportion, most of the signal light is transmitted to the fourth light reflecting device, and a small part of the signal light is transmitted to the photoelectric detector; The photodetector is used to detect signal light and convert the optical signal into an electrical signal; The fourth light reflecting device is composed of a fourth lower reflecting mirror installed on the inner bottom of the housing and a fourth upper reflecting mirror installed on the outer side of the cover plate, and is used to reflect most of the signal light transmitted by the light splitting device from the inside of the housing to the outside of the housing; The third collimator is mounted on the outer side of the cover plate, and is used to receive the signal light passing through the fourth light reflecting device and output the amplified signal light; The side wall of the housing is provided with pins disconnected from the side wall, the pins are used to connect the signal light chip, the temperature control device, the pump light chip, and the photoelectric detector to connect them to the external drive, and the housing is used to install the above devices and has a heat dissipation function; The cover plate is made of a transparent material and is used to transmit the signal light and the pump light.

2. A high reliability fiber laser according to claim 1, characterized in that: The first collimating coupling device and the second collimating coupling device are composed of one or more lenses, and the lenses are spherical, aspherical or cylindrical.

3. A high reliability fiber laser according to claim 1, characterized in that: The first isolator and the second isolator are single-stage or multi-stage isolators.

4. A high reliability fiber laser according to claim 1, characterized in that: The first upper reflector, the first lower reflector, the second upper reflector, the second lower reflector, the fourth upper reflector and the fourth lower reflector are plane reflectors or triangular prisms; the third upper reflector and the third lower reflector are plane reflectors or triangular prisms or dichroic mirrors.

5. The high reliability fiber laser according to claim 1, characterized in that: The optical fibers of the first collimator, the second collimator and the third collimator are single-clad or double-clad optical fibers.

6. A high reliability fiber laser according to claim 1, characterized in that: The pins of the signal light chip, the pump light chip and the photoelectric detector are electrically connected by ultrasonic aluminum wire hot pressing welding, ultrasonic gold wire ball welding or thermal ultrasonic gold wire wedge welding.

7. A high reliability fiber laser according to claim 1, characterized in that: The shell is made of ceramic.

8. The high reliability fiber laser according to claim 1, characterized in that: The cover plate is made of glass.

9. The high reliability fiber laser according to claim 1, characterized in that: The upper and lower surfaces of the cover plate are coated with anti-reflection films for pump light and signal light.

10. The high reliability fiber laser according to claim 1, characterized in that: The gain optical fiber is a single-clad or double-clad optical fiber, and the ions doped therein are erbium ions or erbium-ytterbium co-doped ions.

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