High-power transmission optical communication device

Abstract

The utility model discloses a high-power transmission optical communication device, which comprises an optical resonant cavity, a vortex optical signal coding device and an optical signal transmission decoding device which are fixedly connected with a conical single crystal optical fiber, and is characterized in that: by optimizing signal light generation and designing an optical communication multiplexing modulation and transmission system, a double-end pumped rod-shaped conical single crystal optical fiber is utilized, so that the high-power transmission optical communication is realized; a set of solid annular resonant cavity is built, high-beam-quality stable continuous signal beams with the average power of dozens of watts can be output, meanwhile, a set of vortex optical communication system based on Dammann grating multiplexing different orbital angular momentums is built, the characteristics of vortex beam OAM are combined, a digital micro-mirror device is used for pulse time domain modulation, and the output power of the vortex optical communication system is improved. Loading of information amount with high fidelity and high signal-to-noise ratio is effectively achieved, multiplexing of multiple beams of different vortex signal light loaded with modulation signals in the same beam of light signal can be effectively achieved through a pair of designed conjugate gratings, and high-efficiency, high-speed, large-capacity, high-power and stable optical communication is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of communication, in particular to a high-power transmission optical communication device. Background Art

[0002] In optical communication systems, the continuous lasers commonly used to output optical signals include edge emitting laser chips (EEL), surface emitting laser chips (VCSEL), DFB lasers, ECL lasers, etc. The working principle of these lasers is basically that after electrical excitation, the probability of the working medium emitting stimulated laser light in each direction is the same, and then the two reflective cavity surfaces of the resonant cavity are established in which direction to form a focused laser and emit it. The specific working principle and performance characteristics will vary depending on the type of laser.

[0003] However, these lasers also have some defects in optical communications. For example, during the development process of EEL, problems such as complex array preparation process, difficult device testing, and difficult control of output mode and wavelength were encountered; VCSEL quality is affected by preparation technology, DFB laser is prone to chirp when working in the 1500nm band, so an external modulator is usually required; the manufacture of ECL lasers still relies on the monolithic integration of heterogeneous material systems with high technical requirements, or requires expensive high-precision packaging-level assembly. In addition, since the light source signal generated by the above-mentioned continuous lasers often interferes with the signal light in communication transmission due to aging of the circuit control device and current jitter, and is often not suitable for long-distance optical communication transmission such as submarine optical cables and other places with large signal disturbances due to weak laser light power, these factors may affect the performance and reliability of the optical communication system. Therefore, it is necessary to find a signal light source that can effectively realize high-power transmission in optical communication systems.

[0004] The most widely used technology in optical communication is wavelength division multiplexing (WDM). The basic principle is to combine optical signals of different wavelengths at the transmitting end (multiplexing), couple them to the optical cable line and transmit them in one optical fiber, and separate the optical signals of the combined wavelengths at the receiving end (demultiplexing), and further process them to restore the original signals. The advantages of this technology are large transmission capacity, simple and efficient expansion, high flexibility and reliability, but this method has major defects in cost implementation. In addition, the fierce competition for spectrum resources between signals and limited anti-interference ability also limit the performance of optical communication systems. Utility Model Content

[0005] The purpose of the utility model is to provide a high-power transmission optical communication device, which mainly realizes the resonant output of high-power and high-beam-quality continuous laser signals through a double-end pumped rod-shaped tapered single-crystal optical fiber, and then divides the input continuous laser into four vortex-state light beams through a vortex optical signal encoding device, and uses a digital micromirror device to modulate the amplitude and load information, and finally transmits through coupling to a high-power threshold optical fiber and demodulates each vortex-state light beam at the final output port using a wavelength division multiplexer, thereby realizing signal generation, modulation, transmission and demodulation in the entire system to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solution: a high-power transmission optical communication device, comprising:

[0007] The tapered single crystal fiber is fixedly connected to the optical resonant cavity; the tapered single crystal fiber is fixedly connected to the optical resonant cavity and mainly consists of a pump source collimated optical path, a first concave-convex lens, a second concave-convex lens, a plano-concave mirror, a cavity mirror, a fixture-encapsulated tapered rod-shaped single crystal fiber and a pump light isolator; the tapered rod-shaped single crystal fiber is located between two groups of pump source collimated optical paths; the first concave-convex lens and the second concave-convex lens are located between the tapered rod-shaped single crystal fiber and the pump source collimated optical path; the plano-concave mirror and the cavity mirror are located on the refraction path of the first concave-convex lens and the second concave-convex lens;

[0008] A vortex optical signal encoding device; the vortex optical signal encoding device is composed of a Dammann grating, a first lens group, a digital micromirror device, a second lens group and a conjugate grating, the digital micromirror device is located between the Dammann grating and the conjugate grating, the first lens group and the second lens group are located on both sides of the digital micromirror device, the first lens group is located between the Dammann grating and the array micromirror device, and the second lens group is located between the digital micromirror device and the conjugate grating;

[0009] An optical signal transmission decoding device comprises a lens group coupling device, an optical fiber collimator, a high-power transmission optical fiber and a wavelength division multiplexer.

[0010] Preferably, the tapered single crystal optical fiber fixed connection optical resonant cavity is a ring cavity, and the pump optical isolators are respectively located between the collimated optical path of the pump source and the first concave-convex lens and the second concave-convex lens.

[0011] Preferably, the pump source collimated light path is a pump light path formed by combining a semiconductor pump source with a lens group, and the outer surfaces of the first concave-convex lens and the second concave-convex lens are coated with a coating.

[0012] Preferably, the first concave-convex lens, the second concave-convex lens, the plano-concave mirror and the cavity mirror form a closed reflection and refraction path for directional transmission of the scattered laser light beam.

[0013] Preferably, the Dammann grating can diffract to generate a 2×2 dipole moment vortex beam array, and the surface of the digital micromirror device is divided into four groups of areas.

[0014] Preferably, the Dammann grating has the same structure as the conjugate grating, and the conjugate grating and the Dammann grating have opposite usage scenarios.

[0015] Preferably, the tapered single crystal optical fiber fixed connection optical resonant cavity may be a straight cavity, and a dichroic mirror is further provided in the tapered single crystal optical fiber fixed connection optical resonant cavity.

[0016] Preferably, the tapered single crystal optical fiber fixedly connected optical resonant cavity may be an L-shaped cavity, and the oscillation output laser principle is the same as that of a ring cavity.

[0017] Compared with the prior art, the beneficial effects of the utility model are:

[0018] The utility model optimizes the signal light generation, designs the optical communication multiplexing modulation and transmission system, uses the rod-shaped tapered single crystal optical fiber with double-end pumping, and builds a solid ring resonator, which can output a high-beam-quality stable continuous signal light beam with an average power of tens of watts. At the same time, a vortex light optical communication system based on Dammann grating multiplexing of different orbital angular momentum is built. In combination with the characteristics of vortex light beam OAM, digital micromirror devices are used for pulse time domain modulation to effectively realize the loading of information with high fidelity and high signal-to-noise ratio. A pair of designed conjugate gratings can effectively realize the multiplexing of multiple vortex signal lights with different and modulated signals in the same light signal, thereby realizing high-efficiency, high-speed, large-capacity, high-power and stable optical communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram of the system device of the utility model;

[0020] Figure 2 This is a schematic diagram of the structure of the tapered single crystal optical fiber fixedly connected to the optical resonant cavity of the utility model;

[0021] Figure 3 This is a schematic diagram of the structure of the vortex optical signal encoding device of the utility model;

[0022] Figure 4 This is a schematic diagram of the structure of the optical signal transmission decoding device of the utility model;

[0023] Figure 5 This is a schematic diagram of the design process of the Dammann grating of the utility model;

[0024] Figure 6 The information loading is obtained by controlling the reflection dead time of each vortex light signal of the utility model through DMD;

[0025] Figure 7This is a schematic diagram of the structure of the straight-cavity tapered single-crystal optical fiber fixedly connected to the optical resonant cavity of the utility model;

[0026] Figure 8 This is a schematic diagram of the structure of the L-shaped cavity tapered single crystal optical fiber fixedly connected to the optical resonant cavity of the utility model.

[0027] Numbers in the figure: 1. Tapered single crystal optical fiber fixedly connected to the optical resonant cavity; 101. Pump source collimation optical path; 102. First concave-convex lens; 103. Second concave-convex lens; 104. Plano-concave mirror; 105. Cavity mirror; 106. Tapered rod-shaped single crystal optical fiber; 107. Pump optical isolator; 108. Dichroic mirror; 2. Vortex optical signal encoding device; 201. Dammann grating; 202. First lens group; 203. Digital micromirror device; 204. Second lens group; 205. Conjugate grating; 3. Optical signal transmission decoding device; 301. Lens group coupling device; 302. Optical fiber collimator; 303. High power transmission optical fiber; 304. Demultiplexer. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] The utility model provides Figures 1 to 8 A high-power transmission optical communication device shown includes a tapered single crystal fiber solid continuous light resonant cavity, a vortex optical signal encoding device 2 and an optical signal transmission decoding device 3. The device mainly realizes the resonant output of high-power and high-beam-quality continuous laser signals through a rod-shaped tapered single crystal fiber pumped at both ends. Then, the input continuous laser is divided into four vortex state light beams through the vortex optical signal encoding device 2, and the digital micromirror device 203 is used to modulate the amplitude and load information. Finally, it is transmitted through coupling to a high-power threshold optical fiber and demodulated for each vortex state light beam at the final output port using a wavelength division multiplexer 304, thereby realizing signal generation, modulation, transmission and demodulation in the entire system.

[0030] like Figure 2 The tapered single crystal fiber fixedly connected optical resonant cavity 1 shown is a single crystal fiber solid continuous laser resonant cavity, which mainly includes two groups of pump source collimated light paths 101, a first concave-convex lens 102, a second concave-convex lens 103, a plano-concave mirror 104, a cavity mirror 105, a fixture-packaged tapered rod-shaped single crystal fiber 106, and a pump light isolator 107.

[0031] The pump source collimated optical path 101 is a pump optical path composed of a semiconductor pump source and a lens group, and its main function is to realize the collimated output of the pump signal light and provide sufficient population inversion states for the crystal; the first concave-convex lens 102 and the second concave-convex lens 103 require special coatings to only allow the pump light beam output by the pump source collimated optical path 101 to pass through, and reflect the laser generated by the spontaneous radiation of the crystal tapered rod-shaped single crystal fiber 106; the plano-concave mirror 104 needs to reflect the laser generated by the crystal tapered rod-shaped single crystal fiber 106 in the cavity to the maximum extent; the laser output cavity mirror 105 needs to have a certain transmittance to the laser generated by the crystal tapered rod-shaped single crystal fiber 106, and all the rest are reflected, and the pump optical isolator 107 only allows light in one direction to pass through.

[0032] In this device, a clamp-encapsulated tapered rod-shaped single crystal optical fiber 106 is used as the amplification gain medium, which can effectively reduce the influence of thermal effects on the oscillating output laser, making the oscillating output laser beam of higher quality. Since the pump power absorption distribution in the tapered single crystal optical fiber is longitudinally uneven, its amplification gain coefficient is difficult to expand, which limits the power increase. Therefore, a double-end pumping structure is used to pump the annular solid resonant cavity, and high-power and high-beam quality continuous light oscillation output of about 1μm is achieved in this annular cavity. The collimated optical path 101 of the first pump source provides a particle number flip condition for the crystal tapered rod-shaped single crystal fiber 106, and is focused and coupled to the left end face of the single crystal tapered rod-shaped single crystal fiber 106 through the first concave-convex lens 102. After waveguide transmission in the crystal, it is transmitted through the second concave-convex lens 103 and then hits the pump optical isolator 107 and is blocked. The laser generated by spontaneous radiation in the crystal tapered rod-shaped single crystal fiber 106 is reflected to the plano-concave mirror 104 through the second concave-convex lens 103, and then reflected again to the cavity mirror 105 to generate a continuous laser of the main oscillation. The first concave-convex lens 102, the second concave-convex lens 103, the plano-concave mirror 104, and the cavity mirror 105 constitute a laser resonant cavity. The laser Finally, part of it is output by the cavity mirror 105. Similarly, the pump light beam generated by the collimated optical path 101 of the second pump source is focused and coupled to the right end face of the single crystal fiber through the concave-convex lens, providing a second particle number inversion condition for the crystal tapered rod-shaped single crystal fiber 106, and is transmitted to the first concave-convex lens 102 through the crystal waveguide and blocked by the pump light isolator 107. The laser generated by the crystal oscillates back and forth in the laser resonant cavity composed of the first concave-convex lens 102, the second concave-convex lens 103, the plano-concave mirror 104, and the cavity mirror 105, and is finally output by the cavity mirror 105. Since the crystal and the pump conditions are the same, only one continuous laser will be generated in the solid resonant cavity, and all of them are output by the cavity mirror 105.

[0033] The continuous laser power generated by the tapered single crystal optical fiber fixedly connected to the optical resonant cavity 1 can reach tens of W, and maintain a high beam quality. The laser is then introduced into the vortex optical signal encoding device 2 for beam splitting of different vortex state beams and signal loading modulation.

[0034] like Figure 3 As shown, the vortex optical signal encoding device 2 is composed of a Dammann grating 201, a first lens group 202, a digital micromirror device 203 (DMD), a second lens group 204 and a conjugate grating 205. The Dammann grating 201 is a grating carefully designed according to its principle, which can diffract to produce a 2×2 dipole moment vortex beam array, ensuring that each continuous light beam in the array has the same power and has different orbital angular momentum (OAM), that is, a high-power continuous laser beam is diffracted and evenly divided into four beams of different vortex states with equal power, such as Figure 3 As shown in ①②③④.

[0035] According to the Dammann grating 201 principle, the Dammann vortex grating is a superposition of multiple fork gratings. When designing each fork grating, its sub-period can be optimized separately, so that the intensity of the signal beam of a specific diffraction order in each grating can be maximized. After optimization by the GS iterative algorithm, the process of designing the Dammann grating 201 is as follows: Figure 5 As shown. The first row of Dammann vortices obtained by adding two gratings generate two vortices distributed in the x direction, and the second row of Dammann vortices obtained by adding two gratings generate two vortices distributed in the y direction, and the orbital angular momentum of each vortex is 1 diffraction. The vortex states of the dipole moment vortex beam array are I1 = (-1, 1), I2 = (1, 1), I3 = (-1, -1), and I4 = (1, -1).

[0036] The first lens group 202 is used to collimate the light beams in the four quadrants to the corresponding four areas on the digital micromirror device 203DMD. That is, the vortex light and orbital angular momentum of each quadrant are different, so four beams of light that do not interfere with each other are obtained. DMD is a micro-electromechanical system with electronic input and optical output. It is composed of many small aluminum reflective mirrors. Each mirror is called a pixel. The working state of each pixel is controlled by a high-speed digital optical reflection switch array. The imaging pattern and its characteristics can be determined by controlling the rotation of the micro-mirror around a fixed axis and the time domain response.

[0037] In this device, we use DMD to modulate the four laser beams that are evenly divided and collimated by the Dammann grating 201 in the time domain, that is, we use DMD to control the degree and stagnation time of the light reflected by the micro-mirror in each quadrant. Figure 6As shown, we define a time unit t, where the amount of information transmitted by the optical signal within a 0.25t time unit is 1 bit. During this time period, by adjusting the on and off time of the switch array of each quadrant of the DMD, the length of the vortex light beam information loading time of the corresponding quadrant can be realized, thereby realizing the encoding of different signals. We use different colors (shapes) to distinguish the information loading modulation state of each beam of light, and the light intensity is normalized to 1. As shown in the information time domain diagram in the figure, the red vortex light signal at this moment is (1, 0, 0, 0), the yellow vortex light signal at this moment is (1, 1, 0, 0), the green vortex light signal at this moment is (1, 1, 1, 0), and the blue vortex light signal at this moment is (1, 1, 1, 1). The specific signal encoding can be obtained by controlling the stop time of the micro-mirror on the corresponding quadrant of the DMD according to actual requirements. Here is only an encoding example. In this way, we can get four beams of vortex light loaded with different amounts of information to be transmitted in the system at the same time.

[0038] After the DMD has loaded information, four collimated beams of light in different vortex states are simultaneously converged to the conjugate grating 205 conjugated with the Dammann grating 201 through the second lens group 204, and the separated four beams of light are re-diffracted into the same beam of light for transmission. The conjugate grating 205 is the Dammann grating 201 used in reverse. In this way, we obtain the multiplexing of four different vortex states of light in the same beam of light transmission, and each vortex state of light has a different amount of information loaded in it, achieving a similar effect to wavelength division multiplexing WDM. Of course, we can also design multiple beams of light in vortex states according to actual needs to achieve the multiplexing of more light beams.

[0039] The modulated and multiplexed laser beam will continue to be transmitted to the optical signal transmission decoding device 3. Figure 4 As shown, the optical signal transmission decoding device 3 includes a lens group coupling device 301, a fiber collimator 302, a high-power transmission fiber 303, and finally a de-wavelength division multiplexer 304. The lens group coupling device 301 couples the multiplexed laser beam to the fiber collimator 302 with maximum efficiency, and continuously transmits it in the high-power transmission fiber 303, and finally reaches the signal receiving end to be received and demodulated by the de-wavelength division multiplexer 304, and obtains the corresponding information in each vortex beam, thereby realizing the normal operation of the entire optical communication system.

[0040] The alternative structures in this scheme are:

[0041] The tapered single crystal fiber is fixedly connected to the crystal tapered rod-shaped single crystal fiber 106 in the optical resonant cavity 1. In addition to the tapered rod-shaped single crystal fiber 106, it can also be replaced by a block crystal or an ordinary rod-shaped crystal. The gain medium material can be replaced according to actual needs.

[0042] The collimated optical path 101 of the pump source also needs to correspond to the absorption peak of the gain medium.

[0043] 1. The ring cavity in the tapered single crystal optical fiber fixed connection optical resonant cavity 1 can be replaced with a straight cavity:

[0044] The straight cavity type includes a pump source collimated optical path 101, a first concave-convex lens 102, a second concave-convex lens 103, a dichroic mirror 108, a cavity mirror 105, a fixture-encapsulated tapered rod-shaped single crystal optical fiber 106, and a pump light isolator 107. Among them, the dichroic mirror 108 fully transmits the pump light beam and fully reflects the oscillation laser beam. The resonant cavity of the straight cavity type is composed of the first concave-convex lens 102, the dichroic mirror 108 and the cavity mirror 105, and the oscillation output laser realization principle is the same as the ring cavity.

[0045] 2. The ring cavity in the tapered single crystal optical fiber fixed connection optical resonant cavity 1 can also be replaced with an L-shaped cavity;

[0046] The L-cavity tapered single crystal fiber fixed connection optical resonant cavity 1 comprises a pump source collimated optical path 101, a first concave-convex lens 102, a second concave-convex lens 103, a cavity mirror 105, a pump light isolator 107 and a fixture-encapsulated tapered rod-shaped single crystal fiber 106. The L-cavity resonant cavity is composed of the first concave-convex lens 102, the second concave-convex lens 103 and the cavity mirror 105, and the oscillation output laser realization principle is the same as that of the ring cavity.

[0047] The Dammann grating 201 and the conjugate grating 205 in the vortex optical signal encoding device 2 can be replaced by a pair of suitable metasurface devices or two-dimensional fork gratings with opposite functions.

[0048] The digital micromirror device 203DMD in the vortex optical signal encoding device 2 can be replaced with a spatial light modulator (SLM), that is, a liquid crystal spatial light modulator is used to change the arrangement direction and angle of liquid crystal molecules, thereby changing the effective refractive index of the liquid crystal to change the size of the optical path of each light beam signal, generating phase modulation for each light beam and then loading information. It can also be replaced with an electro-optic modulator, an acousto-optic modulator, or a microlens array.

[0049] Known and potential areas of application:

[0050] High-power continuous laser communication has the advantages of high-speed transmission, strong anti-interference, high security, energy saving and high efficiency. It is very suitable for application in space optical communication, long-distance submarine optical cable transmission, laser communication network, military communication, remote sensing and mapping, etc., providing a powerful solution for future communication needs.

[0051] Its application is roughly as follows:

[0052] Space optical communication: High-power laser communication devices can be used for high-speed data transmission in space. By using high-power lasers, longer communication distances and higher data transmission rates can be achieved.

[0053] Laser communication network: High-power laser communication devices can be used in optical fiber communication networks to achieve high-speed, low-latency, long-distance optical signal transmission. This is very important for future space exploration, scientific research and commercial applications.

[0054] Military Communications: High-power laser communication devices have a wide range of applications in the military field, including battlefield communications, UAV communications, and military satellite communications.

[0055] Remote Sensing and Mapping: High-power laser communications can be used in remote sensing satellites and aircraft to obtain high-resolution images and geographic information of the Earth's surface.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-power transmission optical communication device, characterized in that: include: The tapered single crystal optical fiber is fixedly connected to an optical resonant cavity (1); the tapered single crystal optical fiber is fixedly connected to an optical resonant cavity (1) mainly comprising a pump source collimated optical path (101), a first concave-convex lens (102), a second concave-convex lens (103), a plano-concave mirror (104), a cavity mirror (105), a fixture-packaged tapered rod-shaped single crystal optical fiber (106), and a pump optical isolator (107); the tapered rod-shaped single crystal optical fiber (106) is located between two groups of pump source collimated optical paths (101); the first concave-convex lens (102) and the second concave-convex lens (103) are located between the tapered rod-shaped single crystal optical fiber (106) and the pump source collimated optical path (101); and the plano-concave mirror (104) and the cavity mirror (105) are located on the refraction path of the first concave-convex lens (102) and the second concave-convex lens (103); A vortex optical signal encoding device (2); the vortex optical signal encoding device (2) is composed of a Dammann grating (201), a first lens group (202), a digital micromirror device (203), a second lens group (204) and a conjugate grating (205); the digital micromirror device (203) is located between the Dammann grating (201) and the conjugate grating (205); the first lens group (202) and the second lens group (204) are located on both sides of the digital micromirror device (203); the first lens group (202) is located between the Dammann grating (201) and the array micromirror device; and the second lens group (204) is located between the digital micromirror device (203) and the conjugate grating (205); An optical signal transmission decoding device (3); the optical signal transmission decoding device (3) comprises a lens group coupling device (301), an optical fiber collimator (302), a high-power transmission optical fiber (303) and a wavelength division demultiplexer (304).

2. A high-power transmission optical communication device according to claim 1, characterized in that: The tapered single crystal optical fiber fixed connection optical resonant cavity (1) is a ring cavity, and the pump optical isolator (107) is respectively located between the pump source collimated optical path (101) and the first concave-convex lens (102) and the second concave-convex lens (103).

3. A high-power transmission optical communication device according to claim 1, characterized in that: The pump source collimated optical path (101) is a pump optical path formed by combining a semiconductor pump source with a lens group, and the outer surfaces of the first concave-convex lens (102) and the second concave-convex lens (103) are coated with a coating.

4. A high-power transmission optical communication device according to claim 1, characterized in that: The first concave-convex lens (102), the second concave-convex lens (103), the plano-concave mirror (104) and the cavity mirror (105) form a closed reflection and refraction path for directional transmission of the scattered laser light beam.

5. A high-power transmission optical communication device according to claim 1, characterized in that: The Dammann grating (201) diffracts to generate a 2×2 dipole moment vortex beam array, and the surface of the digital micromirror device (203) is divided into four groups of areas.

6. A high-power transmission optical communication device according to claim 1, characterized in that: The Dammann grating (201) and the conjugate grating (205) have the same structure, and the conjugate grating (205) and the Dammann grating (201) have opposite usage scenarios.

7. A high-power transmission optical communication device according to claim 1, characterized in that: The tapered single crystal optical fiber fixed connection optical resonant cavity (1) may be a straight cavity, and a dichroic mirror (108) is further provided in the tapered single crystal optical fiber fixed connection optical resonant cavity (1).

8. A high-power transmission optical communication device according to claim 1, characterized in that: The tapered single crystal optical fiber fixed connection optical resonant cavity (1) can be an L-shaped cavity, and the oscillation output laser principle is the same as that of a ring cavity.

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