CN107592157B - Device and method for correcting wave front distortion in optical reverse modulation - Google Patents

Abstract

The invention discloses a device for correcting wavefront distortion in optical reverse modulation, including an active end and a passive end connected by an optical path; the invention also discloses a method for correcting wavefront distortion in optical reverse modulation by using the device. The wavefront distorts the beam, and the beam is focused into the stimulated Brillouin scattering cell. After the beam interacts with the liquid medium in the stimulated Brillouin scattering cell, the reverse conjugate light of the distorted beam is generated, and the modulation signal is loaded into the reverse common beam. In terms of the light intensity of the conjugate light, when the reverse conjugate light returns along the original optical path, the phase conjugate distortion can cancel each other out with the wavefront distortion, so that the wavefront phase can be restored to the initial state, thereby realizing the wavefront in the optical reverse modulation. Distortion compensation. The device and the correcting method for correcting the wavefront distortion in the optical reverse modulation of the present invention solve the problem of the wavefront distortion caused by the influence of the atmospheric effect in the reverse modulation laser communication.

Description

Device and correcting method for correcting wavefront distortion in optical reverse modulation

technical field

The invention belongs to the technical field of wireless laser communication, relates to a device for correcting wavefront distortion in optical reverse modulation, and also relates to a method for correcting wavefront distortion in optical reverse modulation using the device.

Background technique

The inverse modulation laser communication is a new type of free space optical communication technology. Compared with the traditional wireless laser communication system, the inverse modulation laser communication system has the advantages of no need for precise positioning of the transmitting end, strong directivity, fast response, simple structure, and high visibility. It has the advantages of large field angle and so on, so it is widely used.

However, in the reverse modulation laser communication system, due to the influence of various atmospheric effects (turbulence, thermal halo, scattering) during the free channel transmission of the laser, the laser energy is lost, the transmission direction is distorted, and the laser wavefront is distorted. It leads to the distortion of the transmitted signal, which seriously restricts the application of laser in the reverse modulation communication system.

Existing patents and literatures use adaptive optics systems to correct atmospheric effects, but adaptive optics systems require a wavefront detection system and a wavefront correction system, which are complex in structure and high in cost, and do not use industrial applications. Therefore, it is necessary to seek new methods to solve the problem of signal distortion caused by wavefront distortion in the laser reverse modulation process, and to improve the effectiveness and accuracy of information transmission.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device for correcting wavefront distortion in optical reverse modulation, so as to solve the problem of wavefront distortion caused by atmospheric effects in reverse modulation laser communication.

Another object of the present invention is to provide a method for correcting wavefront distortion in optical reverse modulation using the above device.

The first technical solution adopted by the present invention is a device for correcting wavefront distortion in optical reverse modulation, including an active end and a passive end;

The active end includes an Nd:YAG laser and a polarizer arranged at the output end of the Nd:YAG laser; also includes a photodetector arranged close to the Nd:YAG laser, and the photodetector is connected to the FPGA demodulation board and the computer A in sequence;

The passive end includes a convex lens, and the left and right sides of the convex lens are respectively provided with an electro-optical modulator EOM and a stimulated Brillouin scattering cell; the electro-optical modulator EOM is connected to the FPGA modulation board and computer B in turn; the stimulated Brillouin scattering cell is filled with With liquid medium FC-72;

The center line of the Nd:YAG laser and the polarizer is parallel to the center line of the photodetector and the electro-optic modulator EOM, and the extension lines of the two center lines pass through the convex lens; the polarizer and the convex lens are connected by an optical path, and the electro-optic modulation The device EOM and the photodetector are connected by an optical path.

The characteristic of the first technical scheme adopted by the present invention also lies in:

The output spot diameter of the Nd:YAG laser is 2mm to 4mm.

The focal length of the convex lens is 5 cm to 20 cm.

The inner cavity of the stimulated Brillouin scattering cell is a PTFE cylindrical cavity.

The second technical solution adopted by the present invention is to utilize the above-mentioned device to correct the wavefront distortion in the optical reverse modulation, which is specifically implemented according to the following steps:

Step 1: The light beam emitted by the Nd:YAG laser enters the polarizer, and the polarizer turns the light beam into vertically polarized light, which is transmitted in the free space channel and reaches the convex lens;

Step 2: After step 1, the emitted light beam is focused by the convex lens into the stimulated Brillouin scattering cell. Brillouin scattering phase conjugate light;

Step 3: The serial port of computer B sends data, sends the data to the FPGA modulation board to process the signal, loads the modulation signal to both ends of the electro-optical modulator EOM, and at the same time, the stimulated Brillouin scattering generated in step 2 is phase-conjugated When the light reaches the electro-optical modulator EOM through the convex lens, the light intensity of the stimulated Brillouin scattering phase conjugate light will change, and the modulation signal is loaded on the light intensity of the stimulated Brillouin scattering phase conjugate light;

Step 4: Return the stimulated Brillouin scattering phase conjugate light processed in step 3 to the photodetector along the original optical path. The photodetector receives the optical signal and converts it into an electrical signal, and then passes through the FPGA demodulation board. The demodulation is restored to the information fed back by the modulation terminal, which is output through the computer A.

The beneficial effects of the present invention are:

(1) The nonlinear phase conjugation technology is applied to the reverse modulation laser communication system, which can compensate the wavefront distortion caused by the influence of atmospheric effects (turbulence, thermal halo, scattering) during the reverse modulation process of the laser, and improve the information transmission efficiency;

(2) Compared with the adaptive optics system without wavefront detection system, the present invention has a simple structure and low cost, and is more conducive to the practical and marketization of the reverse modulation system;

(3) The present invention solves the technical problem of signal distortion caused by wavefront distortion in the laser reverse modulation process, and improves the effectiveness and accuracy of information transmission.

Description of drawings

FIG. 1 is a schematic structural diagram of a device for correcting wavefront distortion in optical reverse modulation according to the present invention.

In the figure, 1. Nd:YAG laser, 2. Polarizer, 3. Convex lens, 4. Stimulated Brillouin scattering cell, 5. Electro-optic modulator EOM, 6. FPGA modulation board, 7. Computer B, 8. Optoelectronics Detector, 9. FPGA demodulation board, 10. Computer A, 11. Liquid medium FC-72, 12. Active end, 13. Passive end.

Detailed ways

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

The device for correcting wavefront distortion in optical reverse modulation according to the present invention, as shown in FIG. 1 , includes an active end 12 and a passive end 13 connected by an optical path;

The active end 12 includes the Nd:YAG laser 1 and the polarizer 2 arranged at the exit end of the Nd:YAG laser 1, and is connected by an optical path between the Nd:YAG laser 1 and the polarizer 2; also includes a set close to the Nd:YAG laser 1 The photodetector 8, the photodetector 8 is connected to the FPGA demodulation board 9 and the computer A 10 in turn through the electrical connection line;

The passive end 13 includes a convex lens 3, the left and right sides of the convex lens 3 are respectively provided with an electro-optic modulator EOM 5 and a stimulated Brillouin scattering cell 4, and the stimulated Brillouin scattering cell 4, the convex lens 3 and the electro-optic modulator EOM 5 Connected in turn through the optical path; the electro-optic modulator EOM 5 is connected to the FPGA modulation board 6 and the computer B 7 in turn through the electrical connecting line; wherein the stimulated Brillouin scattering cell 4 is filled with a liquid medium FC-72 11;

The center line of the Nd:YAG laser 1 and the polarizer 2 is parallel to the center line of the photodetector 8 and the electro-optic modulator EOM 5, and the extension lines of the two center lines pass through the convex lens 3; the polarizer 2 and the convex lens 3 is connected by an optical path, and the electro-optical modulator EOM 5 and the photodetector 8 are connected by an optical path.

In the device of the present invention for correcting wavefront distortion in optical reverse modulation:

The output spot diameter of the Nd:YAG laser 1 is 2 mm to 4 mm.

The focal length of the convex lens 3 is 5 cm to 20 cm.

The inner cavity of the stimulated Brillouin scattering cell 4 is a Teflon cylindrical cavity.

The smaller the output spot diameter of the Nd:YAG laser 1 is, the better the nonlinear optical effect of the light beam in the stimulated Brillouin scattering cell 4 and the liquid medium FC-72 11; The energy of the stimulated Brillouin scattering phase conjugate light reflected back in the Brillouin scattering cell 4 is larger.

The specific steps of the method for correcting the wavefront distortion in the optical reverse modulation using the above device are as follows:

Step 1: The light beam emitted by the Nd:YAG laser 1 enters the polarizer 2, and the polarizer 2 turns the light beam into vertically polarized light, which is transmitted in the free space channel and reaches the convex lens 3;

Step 2: After step 1, the emitted light beam is focused by the convex lens 3 into the stimulated Brillouin scattering cell 4, where the light beam interacts with the liquid medium FC-72 11 nonlinearly in the stimulated Brillouin scattering cell 4. The effect produces stimulated Brillouin scattering phase conjugate light;

Step 3: The serial port of computer B 7 sends data, sends the data to the FPGA modulation board 6 to process the signal, loads the modulated signal to both ends of the electro-optic modulator EOM 5, and simultaneously transmits the stimulated Brillouin scattering generated in step 2 The phase conjugate light reaches the electro-optic modulator EOM 5 through the convex lens 3, the light intensity of the stimulated Brillouin scattering phase conjugate light will change, and the modulation signal is loaded on the light intensity of the stimulated Brillouin scattering phase conjugate light;

Step 4: The stimulated Brillouin scattering phase conjugate light processed in Step 3 is returned to the photodetector 8 along the original optical path, and the photodetector 8 receives the optical signal and converts it into an electrical signal, which is then demodulated by the FPGA The demodulation of the board 9 is restored to the information fed back by the modulation terminal, which is output through the computer A 10 .

Through the above steps, the entire reverse modulation optical communication process is realized, information transmission is realized, and the wavefront distortion of the light beam in the reverse modulation system is compensated.

The present invention is a device and method for correcting wavefront distortion in optical reverse modulation. Its working principle is as follows: in the process of emitting a light beam from the active end 12 to the passive end 13, the turbulence in the atmospheric channel will cause the wavefront distortion of the light beam. The passive end 13 focuses the wavefront distorted beam into the stimulated Brillouin scattering cell 4 through a convex lens, and the light interacts with the medium in the stimulated Brillouin scattering cell 4 to generate reverse conjugate light of the distorted beam. When the reverse conjugate light returns to the atmospheric channel along the original optical path again, the phase conjugate distortion and the wavefront distortion information can cancel each other out, so that the wavefront phase returns to the initial state, thus realizing the compensation of the wavefront distortion.

The device and method for correcting wavefront distortion in optical reverse modulation according to the present invention, compared with the traditional method for correcting wavefront distortion of a self-adaptive optical system, not only can well solve the problem of wavefront distortion in optical reverse modulation, but also has no wavefront distortion. The front detection system has simple structure and low cost, and is more conducive to the practical and marketization of the reverse modulation system.

Claims (2)

1. The device for correcting wave front distortion in optical inverse modulation is characterized by comprising an active end (12) and a passive end (13);

the driving end (12) comprises an Nd-YAG laser (1) and a polaroid (2) arranged at the emitting end of the Nd-YAG laser (1); the device also comprises a photoelectric detector (8) which is arranged close to the Nd-YAG laser (1), the diameter of an emergent light spot of the Nd-YAG laser (1) is 2-4 mm, and the photoelectric detector (8) is sequentially connected with an FPGA (field programmable gate array) demodulation board (9) and a computer A (10);

the passive end (13) comprises a convex lens (3), the focal length of the convex lens (3) is 5-20 cm, and the left side and the right side of the convex lens (3) are respectively provided with an electro-optical modulator EOM (5) and a stimulated Brillouin scattering pool (4); the electro-optical modulator EOM (5) is sequentially connected with an FPGA modulation board (6) and a computer B (7); the stimulated Brillouin scattering pool (4) is filled with a liquid medium FC-72 (11); the inner cavity of the stimulated Brillouin scattering pool (4) is a polytetrafluoroethylene cylindrical cavity;

the center connecting line of the YAG laser (1) and the polaroid (2) is parallel to the center connecting line of the photoelectric detector (8) and the electro-optical modulator EOM (5), and the extension lines of the two center connecting lines pass through the convex lens (3); the polaroid (2) is connected with the convex lens (3) through an optical path, and the electro-optical modulator EOM (5) is connected with the photoelectric detector (8) through an optical path.

2. A method for correcting wavefront distortion in optical inverse modulation using the apparatus of claim 1, comprising the steps of:

step 1: YAG laser (1) sends light beam into a polaroid (2), the polaroid (2) changes the light beam into vertical polarized light, and the vertical polarized light is transmitted in a free space channel and reaches a convex lens (3);

step 2: after the step 1, the emitted light beams are focused to the stimulated Brillouin scattering pool (4) through the convex lens (3), and the light beams interact with the liquid medium FC-72(11) in the stimulated Brillouin scattering pool (4) to generate nonlinear effect to generate stimulated Brillouin scattering phase conjugate light;

and step 3: the computer B (7) sends data through a serial port, the data are sent into an FPGA modulation board (6) to be processed, modulation signals are loaded to two ends of an electro-optical modulator EOM (5), meanwhile, stimulated Brillouin scattering phase conjugate light generated in the step (2) reaches the electro-optical modulator EOM (5) through a convex lens (3), light intensity of the stimulated Brillouin scattering phase conjugate light changes, and the modulation signals are loaded on the light intensity of the stimulated Brillouin scattering phase conjugate light;

and 4, step 4: and (3) returning the stimulated Brillouin scattering phase conjugate light processed in the step (3) to the photoelectric detector (8) along an original optical path, receiving the optical signal by the photoelectric detector (8) and converting the optical signal into an electric signal, demodulating the electric signal by the FPGA demodulation board (9), reducing the electric signal into information fed back by a modulation end, and outputting the information by the computer A (10).