CN110854657B - A resonant optical communication device without intracavity interference based on optical frequency doubling - Google Patents

Abstract

The invention relates to a resonant optical communication device without intra-cavity interference based on optical frequency doubling, comprising a master and a slave, wherein the master includes a retro-reflection modulation module and a resonant light emission composed of a first retro-reflector and a gain medium module, the slave machine includes a second retro-reflector, the resonant optical path between the first retro-reflector and the second retro-reflector constitutes a free space resonant cavity, and the retro-reflection modulation module includes a third retro-reflector arranged along the optical path. A rear reflector, an optical modulator, an optical frequency multiplier for generating a frequency-doubled beam, and a third lens. Compared with the prior art, the present invention has the advantages of high-rate resonant optical communication, mobility, and interference avoidance.

Description

A resonant optical communication device without intracavity interference based on optical frequency doubling

technical field

The invention relates to the field of wireless optical communication, in particular to a resonant optical communication device without intracavity interference based on optical frequency doubling.

Background technique

With the development of information technology, the carrier frequency of a wireless communication system is getting higher and higher, because a higher carrier frequency can provide a larger bandwidth. At present, the frequency of millimeter-wave communication commonly studied has reached tens of GHz, but the carrier of higher frequency is the light wave in the frequency band of several hundreds of THz. In the foreseeable future, the use of light waves for wireless communication will be an important technical means, providing data transmission channels for applications such as virtual reality and augmented reality that require large-bandwidth communication.

However, the challenge facing wireless optical communication is the trade-off between received power and mobility. Specifically, common LED lights can realize optical communication with wide coverage, and mobile terminals can move flexibly within the coverage of lights. However, the receiving power of mobile terminals is extremely low, and its signal-to-noise ratio is often difficult to meet the requirements of high-speed communication. The other is to use concentrated LEDs or lasers to achieve directional optical communication. This type of technology generally requires the use of mechanical or non-mechanical beam steering devices to direct the beam to the receiver. Mechanical devices generally use a micro-electromechanical system to control the rotation of the mirror to achieve beam steering. Such devices have a slow response speed and low precision. Common non-mechanical beam steering devices use gratings or spatial light modulators, which have a high response speed, but the difficulty lies in the need to accurately position the receiver in advance, which is a great challenge in terms of technology and cost.

In Chinese Invention Patent 2017110620229.8 "Wireless Communication Device Based on Distributed Optical Resonator" and Chinese Invention Patent 201811209197.4 "An Energy-carrying Communication Device Based on Resonant Beam", the solution of using free-space laser resonator to realize wireless communication is mentioned. This kind of scheme has higher received power and better mobility, and is a technology to break through the bottleneck of conventional wireless communication.

However, directly modulating the intra-cavity beam of free-space laser resonators inevitably faces the problem of intra-cavity echo interference, that is, the modulated beam propagates back and forth in the cavity, which affects the subsequent communication process. Due to the existence of echo interference, this scheme can only achieve low-rate modulation, which fails to fully reflect the advantages of free-space laser resonators in wireless optical communication.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a resonant optical communication device without intra-cavity interference based on optical frequency doubling in order to overcome the above-mentioned defects of the prior art.

The object of the present invention can be realized through the following technical solutions:

An intra-cavity interference-free resonant optical communication device based on optical frequency doubling, comprising a host and a slave, wherein the host includes a retro-reflection modulation module and a resonant light-emitting module composed of a first retro-reflector and a gain medium. The slave machine includes a second retro-reflector, the resonant optical path between the first retro-reflector and the second retro-reflector constitutes a free space resonant cavity, and the retro-reflection modulation module includes a third rear reflector arranged along the optical path , an optical modulator, an optical frequency multiplier for generating a frequency-doubled beam, and a third lens.

The first retro-reflector is composed of a first back reflector and a first lens, the second retro-reflector is composed of a second lens and a second back reflector, and the second back reflector is coated with wavelength selective properties The film is used to transmit the frequency-doubled beam and reflect the resonant beam.

When the device adopts an optical path folded structure, the pupil of the first retroreflector coincides with the pupil position of the retroreflection modulation module, the gain medium is arranged at the pupil position, and the reflective surface is arranged behind the gain medium.

The reflective surface is a reflective surface with partial transmittance, the third lens, the optical frequency multiplier, the optical modulator and the third rear reflector are sequentially arranged in the transmission direction of the reflective surface, and the A retro reflector is positioned in the reflection direction of the reflective surface.

When the device adopts an optical path through-type structure, the optical frequency multiplier is arranged on the resonant optical path between the second rear reflector and the first lens, and the first rear reflector is coated with a wavelength-selective film is used to transmit the frequency-doubling beam and reflect the resonant beam. The third lens, the light modulator and the third rear reflector are sequentially arranged in the transmission direction of the first rear reflector.

The gain medium is disposed at the pupil of the first retroreflector.

The third lens is composed of two lenses arranged in parallel.

The wavelength-selective film is specifically a frequency-doubling beam antireflection film and a resonant beam antireflection film.

The slave also includes a condenser lens and a photodetector arranged behind the second rear reflector to receive the frequency-doubled beam.

The frequency of the frequency-doubling beam is not less than twice the frequency of the resonant beam.

Compared with the prior art, the present invention has the following advantages:

The invention creatively designs a composite mirror group structure, which can lead out a part of the resonant light beam with power for frequency doubling and modulation, while the other part of the resonant light beam maintains resonance in the cavity. A wavelength-selective retro-reflector is used in the slave to separate the frequency-doubling beam and the resonant beam. In this design, the frequency-doubling beam carrying the modulation information directly utilizes the spontaneously established path of the resonant beam, and does not oscillate in the free-space resonant cavity, thus avoiding the problem of echo interference in the cavity. Therefore, the present invention realizes high-speed resonant optical communication, and the extracted frequency-doubling modulated light beam can be reflected back according to the original path and re-enter the resonant light beam path. Since the spontaneous establishment property of the resonant beam is the fundamental reason for the mobility of the communication link, the design of this patent to re-enter the resonant beam path of the frequency-doubled modulated beam maintains the mobility of the communication device.

Description of drawings

FIG. 1A is a schematic diagram of the structure and principle of a telecentric cat's eye retroreflector.

FIG. 1B is a schematic diagram of the structure of a free-space laser resonator based on a telecentric cat-eye retroreflector.

FIG. 2 is a schematic structural diagram of a resonant optical communication device without intracavity interference based on optical frequency doubling of the present invention.

FIG. 3 is a schematic structural diagram of the embodiment of the optical path folding type shown in FIG. 2 .

FIG. 4 is a schematic structural diagram of the embodiment of the optical path through type shown in FIG. 2 .

Description of marks in the figure:

1. Main unit, 11, Rear mirror, 12, Lens, 13, Pupil, 14, Beam, 150, Rear mirror, 151, Lens, 152, Pupil, 160, Rear mirror, 161, Lens, 162, pupil, 17, gain medium, 18, resonant beam, 2, slave, 20, resonant light emission module, 201, first retroreflector, 202, gain medium, 203, reflective surface with partial transmittance, 21, Retroreflection Modulation Module, 22, Second Retroreflector, 23, Condenser Lens, 24, Photodetector, 3, Free Space, 210, Third Back Reflector, 211, Optical Modulator, 212, Optical Frequency Doubler , 213, third lens, 2130, lens, 2131, lens, 4, reflective surface, 2011, first rear mirror, 2012, first lens, 221, second lens, 222, second rear mirror, 80, The pupil of the first retro-reflector, 81, the pupil of the second retro-reflector, 82, the pupil of the retro-reflection modulation module.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Figures 1A and 1B together illustrate the principle of a free-space laser resonator based on a telecentric cat's eye retroreflector. 1A is a structure of a telecentric cat's eye retroreflector, comprising a lens (12) and a rear reflector (11) located at the focal plane of the lens (12). According to the principles of geometrical optics, any light passing through the focal point of a lens passes through the lens and is then incident perpendicular to the focal plane on this side of the lens. If other light beams are parallel to the light rays passing through the focal point of the lens, they will be focused to the same point after passing through the lens. After the light reflected by the rear reflector at the focal plane passes through the lens, it is still parallel to the incident light, that is, the reflected light is reflected in the opposite direction to the incident light. According to the above principle, it is considered that there is a pupil (13) at the focal point of the lens (12), and any parallel light beam (14) incident through the pupil (13) will pass through the pupil (13) after being reflected by the cat-eye retroreflector ) and coincides with the path of the original incident beam (14).

Figure 1B is an example of a free-space laser resonator based on a telecentric cat's eye retroreflector. In this example, the first retro-reflector is composed of the rear reflector (150) and the lens (151); the second retro-reflector is composed of the rear reflector (160) and the lens (161). According to the principle of cat's eye retroreflector, the parallel light beam on the connecting line between the pupil of the first retroreflector (152) and the pupil of the second retroreflector (162) can oscillate back and forth regardless of the first retroreflector and the second retroreflector. The relative position between the two retroreflectors. Thus, the first retroreflector and the second retroreflector constitute a free space resonant cavity. The gain medium (17) is located at the pupil (152) of the first retroreflector. Since the path of the oscillating beam must pass through the pupil (152), the size of the gain medium here can be made very small, and the energy utilization efficiency higher. The free-space laser resonant cavity is constituted by the free-space resonant cavity and the gain medium in the cavity. According to the laser principle, the resonant beam with concentrated energy can be generated spontaneously in the cavity. Therefore, modulation of information can be achieved by changing the resonant beam in the cavity. The intracavity resonant beam is generated spontaneously, connecting the sending and receiving devices, and the beam can still be generated during the movement of the device, which provides mobility to the communication system.

This patent discloses a resonant optical communication device without echo interference based on optical frequency doubling, which includes a host and a slave. A first retro-reflector is included in the master and a second retro-reflector is included in the slave. In the host, a gain medium placed in the optical path between the first retroreflector and the second retroreflector is also included. The two retroreflectors and the connectable optical paths between them constitute a free-space resonant cavity, and photons can move back and forth in the free-space resonant cavity to generate oscillations. Therefore, after the gain medium absorbs external energy and the population inversion occurs, the photons generated by spontaneous radiation of the gain medium enter the free space resonant cavity and oscillate back and forth between the first retroreflector and the second retroreflector. The photons repeatedly pass through the gain medium during the oscillation process, and their power is continuously amplified, finally forming a resonant beam with high power density.

All retro-reflectors have a pupil area, and all retroreflected light beams must pass through the pupil of the retro-reflector, so the resonant light beam must pass through the pupils of the first retro-reflector and the second retro-reflector. The gain medium should be placed in the pupil region of the first retroreflector so that any resonant beam generated on its path will pass through the gain medium. This configuration can reduce the volume of the gain medium, thereby saving cost and reducing power loss.

Direct modulation of resonant light in a cavity faces many problems. On the one hand, the power of the modulated resonant beam fluctuates, which will break the balance between the resonant optical power in the cavity and the dynamic gain of the gain medium, making the resonant beam power more unstable. On the other hand, due to the nature of the resonant beam, if the communication modulation is performed in the free space resonant cavity, the modulated beam will become a back-and-forth motion, which will become an echo interference that affects the subsequent communication.

In view of the above problems, this patent proposes to use optical frequency doubling and filtering to realize resonant optical communication without echo interference. Different from the resonant beam, the frequency doubled beam is generated by the resonant beam or part of the beam drawn from the resonant beam through an optical frequency doubler, and its frequency is twice or higher than the original resonance beam. Therefore, this patent also includes at least one optical frequency multiplier, which may be located in the path of the resonant beam, or in the path of the beam extracted from the resonant beam.

On the path passed by the resonant beam in the host, at least one reflective surface with partial transmittance is included, which is used to draw out the frequency-doubling beam merged in the resonant beam or directly draw out a part of the resonant beam. Depending on the location of the optical frequency doubler, there are two options:

a) When the frequency doubling crystal is placed on the resonant optical path, the frequency doubling beam has been generated on the resonant beam path and mixed with the resonant beam, so the reflective surface with partial transmittance should be coated with a wavelength-selective film to make the frequency doubling beam Separated from the resonant beam, wherein the separated frequency-doubling beam propagates to the retro-reflection modulation module;

b) When the frequency doubling crystal is placed on the path of the beam drawn from the resonant beam, the reflective surface with partial transmittance should separate a part of the beam from the resonant beam according to a certain power ratio, so that it becomes a double beam after passing through the frequency doubling crystal. frequency beam and propagate to the retroreflection modulation module.

In different implementations, the reflective surface with partial transmittance may be a separate mirror, or may use a rear mirror within the first retro-reflector structure.

Therefore, a retro-reflection modulation module is included in the host to modulate the frequency-doubling beam, and reflect the modulated frequency-doubling beam according to the original incident direction. Since the frequency doubled beam is generated by the resonant beam through the frequency doubler, and the frequency doubler will not affect the beam propagation direction, the frequency doubled beam reflected by the retroreflection modulation module can also return to the resonant beam path, and Propagated to slaves.

In the host, the retro-reflection modulation module includes at least one retro-reflector and a light modulator. The pupil of the first retro-reflector or its equivalent pupil for forming the resonant beam should overlap with the pupil of the retro-reflector within the retro-reflection modulation module. The direction of the intracavity resonant beam is dynamically changed, depending on the relative positions of the master and slave. However, the pupil of the retro-reflector is stationary and depends only on the configuration of the retro-reflector. Therefore, in the structure disclosed in the present patent, the pupil of the first retro-reflector or its equivalent pupil and the pupil of the retro-reflector in the retro-reflection modulation module should be overlapped, and only in this case can the resonant beam be satisfied at the same time Pass the requirements of the pupil of the first retro-reflector in the host and the pupil of the retro-reflector in the retro-reflection modulation module. The equivalent pupil is another fixed area other than its pupil through which a part of the light beam branched by the retroreflector must pass through the transformation of the optical device. When the pupil of the retro-reflection modulation module overlaps with the equivalent pupil of the first retro-reflector, the beam split from the resonance beam can also be reflected back to the resonance beam path by the original path.

The slave also includes a partially transmissive reflective surface with wavelength-selective properties, and the function of the reflective surface is to separate the resonant beam and the frequency-doubled beam. According to various embodiments, the partially transmissive reflective surface having wavelength selective properties may be configured to reflect the resonant light beam and transmit the frequency doubled light beam, or to reflect the frequency doubled light beam and transmit the resonant light beam. According to different embodiments, the partially transmissive reflective surface with wavelength-selective properties can either be a separate device, or it can borrow a reflective surface inside the second retro-reflector structure.

In the slave, a concentrator and at least one photodetector are also included. The concentrator is used to collect the frequency-doubled light beam extracted by the partially transmissive reflective surface with wavelength-selective properties, and concentrate the frequency-doubled light beam on the photodetector. The photodetector receives the frequency-doubled optical signal that has been modulated and converts it into a corresponding electrical signal.

Example 1:

As shown in FIG. 2 , the host 1 of the resonant optical communication device without intracavity interference based on optical frequency doubling includes a resonant light generating module 20 and a retroreflection modulation module 21 . The resonant light generating module 20 includes a first retroreflector 201 , a gain medium 202 and a reflective surface 203 with partial transmittance, and the slave 2 includes a second retroreflector 22 , a concentrator 23 and a photodetector 24 .

The optical path between the first retro-reflector 201 and the second retro-reflector 22 in FIG. 2 constitutes a free space resonant cavity. The gain medium 202 is placed at the pupil position of the first retroreflector 201 and has the functions of frequency selection and power amplification. The specific material of the gain medium optionally includes a neodymium-doped yttrium aluminum garnet Nd:YAG crystal, a neodymium-doped yttrium vanadate Nd:YVO4 crystal, a gallium arsenide GaAs semiconductor material, and the like. Exemplarily, in the embodiment of FIG. 2, Nd:YAG crystal is selected as the gain medium, and a 1064 nm semiconductor laser is used as the pumping source, so the wavelength of the resonance beam formed in the free space 3 is 1064 nm.

The reflective surface 203 with partial transmittance is placed behind the gain medium, that is, also in the pupil area of the first retro reflector 201 , which can increase the energy conversion efficiency of the gain medium. The reflective surface 203 with partial transmittance reflects a part of the resonant light beam to the first retro-reflector 201 , and transmits another part of the resonant light beam to the retro-reflection modulation module 21 .

The retro-reflection modulation module 21 includes an optical frequency doubler and an optical modulator, so the 1064 nm light beam transmitted by the reflective surface 203 generates a 532 nm frequency doubled light beam after passing through the optical frequency doubler. Further, the frequency-doubled beam of 532 nm is modulated by an optical modulator. Modulators include light intensity modulators, phase modulators made of lithium niobate crystals, or electro-absorption modulators made of semiconductor materials. Exemplarily, this solution selects a lithium niobate light intensity modulator to change the amplitude or intensity of the 532 nm light beam so that the light beam carries information. Finally, the retro-reflective modulator 21 reflects the modulated 532nm frequency-doubled beam back on the path of the original 1064nm beam incident. According to the setting, the 532nm frequency-doubled beam reflected by the retroreflector 21 and the 1064nm beam reflected by the first retroreflector 201 converge at the pupil position where the gain medium 202 is located, and propagate through the free space 3 according to the same optical path to from machine 2.

In FIG. 2 , the second retroreflector 22 in the slave 2 has a wavelength selection property, that is, the light of 1064 nm is reflected back in the form of retroreflection, and the light of 532 nm is led out of the resonant beam path. Specifically, the reflection surface of the second retro reflector 22 is coated with an anti-reflection film of 1064 nm and an anti-reflection film of 532 nm. Then, the light of 532 nm is transmitted and then collected by the condenser 23 on the photodetector 24 . Finally, the photodetector 24 converts the optical signal into an electrical signal and outputs it.

Example 2

Figure 3 shows a folded structure of the present invention. The host 1 in this embodiment includes the following parts:

a A retro-reflection modulation module composed of a rear mirror 310, a light modulator 211 and a third lens 213;

b The first retroreflector composed of the first rear reflector 2011 and the first lens 2012;

c the gain medium 202 at the first retroreflector pupil 80;

d is inside the retroreflective modulation module, that is, the optical frequency multiplier 212 between the optical modulator 211 and the third lens 213;

e has a reflective surface 4 with partial transmittance.

The slave 2 of the embodiment shown in FIG. 3 includes the following parts:

a A second retroreflector composed of a coated second rear reflector 222 and a second lens 221;

b Condenser consisting of focusing lens 23;

c Photodetector 24.

In FIG. 3, according to the reflection effect of the reflective surface 4 with partial transmittance, the first retro-reflector and the second retro-reflector constitute a free space resonant cavity, that is, between the first and the second retro-reflector Resonant light beams can be generated between the two, and these light beams all pass through the pupil 80 of the first retro-reflector and the pupil 81 of the second retro-reflector. Exemplarily, the embodiment shown in FIG. 3 uses Nd:YAG crystal as the gain medium, so the wavelength of the generated resonant beam is about 1064 nm. A small part of the resonant light beam can pass through the reflective surface 4 with transmittance and be transmitted to the retro-reflection modulation module. Since the pupil 80 of the first retro-reflector is also the pupil of the retro-reflection modulation module, the light beam passing through the reflective surface 34 can be reflected back by the original path. Specifically, before being reflected back to the pupil 80 of the first retro-reflector, the light beam passing through the reflection surface 4 will also pass through the optical frequency doubler 212 to become frequency doubled light with a wavelength of about 532 nm. Then the frequency doubled light passes through the light modulator 211 to become a modulated frequency doubled light beam. After the reflection of the third rear reflector 210 and the action of the third lens 213, the modulated frequency-doubled beam finally returns to the pupil 80 of the first retro-reflector, coincides with the resonant beam, and propagates through the free space 3 to the machine.

In FIG. 3 , since the coated second rear reflector 222 is coated with a reflective film for the light wave with a wavelength of 1064 nm of the resonant beam and an anti-reflection film for the light wave with a wavelength of 532 nm of the frequency-doubled light, the resonant beam is reflected by the second rear reflector 222 Reflected back to the host 1 , the modulated frequency-doubled light beam can pass through the second rear reflector 222 and be concentrated on the photodetector 24 by the focusing lens 23 .

Example 3

FIG. 4 is another more specific schematic embodiment based on FIG. 2 , and a through-type structure is designed. Among them, the host 1 includes the following parts:

a first retroreflector composed of a first rear reflector 2011 with partial transmittance and a first lens 2012;

b. A retroreflective modulation module consisting of a third rear reflector 210, a light modulator 211, and a third lens 213 including two lenses arranged in parallel;

c the gain medium 202 at the pupil of the first retroreflector;

d is inside the first retroreflector, ie the optical frequency doubler 43 between the first rear mirror 2011 with partial transmittance and the lens 442 .

The slave 2 of the embodiment shown in FIG. 4 includes the following parts:

a second retroreflector consisting of a lens and a second rear reflector 222 and a second lens 221 having partial transmittance;

b has a condenser composed of a focusing lens 23;

c Photodetector 24.

In Figure 4, the first retroreflector and the second retroreflector constitute a free space stimulated radiation resonant cavity. Due to the frequency selection and amplification of the gain medium 202, a resonant light beam with concentrated energy is formed between the first retroreflector and the second retroreflector. According to the nature of retroreflection, the resonant light beam must pass through the pupil 80 of the first retroreflector and the pupil 81 of the second retroreflector. Illustratively, in this embodiment, Nd:YAG is specifically used as the gain medium material, and the frequency of the generated resonant beam is 1064 nm.

In FIG. 4, since the optical frequency doubler 212 is placed on the path of the resonant beam, a small part of the resonant beam moving toward the first rear reflector 2011 becomes a frequency-doubled beam of 531 nm. The first rear reflector 2011 is coated with a 532nm antireflection coating and a 1064nm antireflection coating, so the first rear reflector 2011 reflects all the resonant beams back, and the 532nm frequency doubled beam can pass through the first rear reflector 2011.

In FIG. 4 , the first rear reflection mirror 2011 also coincides with the focal plane of the first lens 2012 , so the first rear reflection mirror 2011 can be equivalent to the first lens 2012 . Since the light beam reflected by the first back reflector 2011 and the transmitted light beam can be regarded as mirror symmetry, the plane where the first lens 2012 and the first back reflector 2011 are located can also be regarded as mirror images of the first retroreflector. Therefore, the frequency-doubling light beam transmitted by the first rear reflector 2011 and entering the retro-reflection modulation module must pass through the focal position of the first lens 2012 .

In FIG. 4 , a telecentric cat's eye retroreflector that reflects the frequency-doubling beam is also formed by the first rear reflector 2011 and the lens 2131 , and therefore has the pupil 82 of the retroreflection modulation module. In this embodiment, the pupil 82 of the retroreflective modulation module is also at the focal position of the first lens 2012 . Therefore, the frequency-doubling beam entering the retro-reflector modulation module through the first rear reflector 2011 must also pass through the pupil 82 of the retro-reflection modulation module to meet the requirements of the telecentric cat's eye retro-reflector for the incident beam path. The frequency-doubled light beam is modulated by the light modulator 211 inside the telecentric cat's eye retroreflector that reflects the frequency-doubled light, and becomes a modulated frequency-doubled light beam. Finally, due to the action of the retro-reflector, the modulated frequency-doubling beam will also pass through the pupil 82 of the retro-reflection modulation module, and be reflected back to the first rear reflector 2011 by the original path, and after passing through the first rear reflector 2011, it will be combined with The resonant beams coincide and finally propagate to the slave 2 through the free space 3.

In FIG. 4 , the second rear reflector 222 in the slave 2 is coated with an anti-reflection coating for 1064 nm light and an anti-reflection coating for 532 nm light. The resonant light beam is reflected back to the host 1 by the second back reflector 222 , and the modulated frequency-doubled light beam passes through the second back reflector 222 and is concentrated on the photodetector 24 by the focusing lens 23 .

When the light modulator 211 is a multiple quantum well semiconductor electro-optic modulator, it can also be placed at the pupil 82 of the retroreflective modulation module. Since all the frequency-doubled light must pass through the pupil 82 position, the area of the multi-quantum well electro-optic modulator can be set smaller, which helps to improve the modulation rate.

Those skilled in the art will appreciate that the present invention is not limited to those that have been specifically shown or described above, the scope of the present invention includes what will come to mind to those skilled in the art upon reading the above description and which are not in the prior art out of context Combinations and sub-combinations of the various features described, as well as variations and modifications thereof.

Claims (8)

1. A resonant optical communication device without intracavity interference based on optical frequency doubling, comprising a host (1) and a slave (2), the host (1) comprising a retroreflection modulation module (21) and a first A resonant light emitting module (20) composed of a retroreflector (201) and a gain medium (202), the slave (2) includes a second retroreflector (22), a first retroreflector (201) and a second retroreflector (201) The resonant optical path between the two retro-reflectors (22) constitutes a free space resonant cavity, and it is characterized in that the retro-reflection modulation module (21) comprises a third rear reflector (210), an optical modulator ( 211), an optical frequency multiplier (212) for generating a frequency-doubled beam, and a third lens (213), wherein the first retroreflector (201) is composed of a first rear reflector (2011) and a first lens ( 2012), the second retroreflector (22) consists of a second lens (221) and a second back reflector (222), the second back reflector (222) is coated with a wavelength-selective film, using By transmitting the frequency-doubling beam and reflecting the resonant beam, when the device adopts an optical path folded structure, the pupil of the first retroreflector (201) coincides with the pupil position of the retroreflection modulation module (21), and the gain medium (202) ) is placed at this pupil position and a reflective surface (4) is placed behind the gain medium (202). 2 . The resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 1 , wherein the reflective surface (4) is a reflective surface with partial transmittance, and the The third lens (213), the optical frequency multiplier (212), the optical modulator (211) and the third rear reflector (210) are sequentially arranged in the transmission direction of the reflective surface (4). The reflector (201) is arranged in the reflection direction of the reflection surface (4). 3. A kind of resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 1, characterized in that, when the device adopts an optical path through-type structure, the optical frequency doubler (212) is arranged on the resonant optical path between the second rear reflection mirror (2011) and the first lens (2012), and the first rear reflection mirror (2011) is coated with a wavelength selective film to transmit the frequency-doubling beam, To reflect the resonant light beam, the third lens (213), the light modulator (211) and the third rear reflection mirror (210) are sequentially arranged in the transmission direction of the first rear reflection mirror (2011). 4. The resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 3, wherein the gain medium (202) is arranged on the light of the first retroreflector (201) pupil. 5 . The resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 3 , wherein the third lens ( 213 ) is composed of two lenses arranged in parallel. 6 . 6. a kind of resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 3, is characterized in that, the film of described wavelength selective property is specifically frequency doubling beam antireflection film and resonant beam booster. Reverse film. 7. The resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 1, wherein the slave (2) further comprises a second rear reflector (222) A condenser lens (23) and a photodetector (24) are received at the rear of the frequency-doubled beam. 8 . The resonant optical communication device without intracavity interference based on optical frequency doubling according to claim 1 , wherein the frequency of the frequency doubling beam is not less than twice the frequency of the resonant beam. 9 .

Images