阅读说明：本技术 一种激光脉冲位置编码控制方法、控制系统、光通信设备 (Laser pulse position coding control method, control system and optical communication equipment ) 是由 张子昂 韩兴伟 付靖祺 马磊 于 2020-06-24 设计创作，主要内容包括：本发明属于空间激光脉冲远距离时间传递技术领域,公开了一种激光脉冲位置编码控制方法、控制系统、光通信设备,通过对激光器输出激光脉冲偏振态进行选择控制,将选择的激光脉冲输入延迟光路,实现激光脉冲位置编码加载特定光脉冲时刻编码信息。本发明将时刻信息进行编码,通过该发明激光脉冲调制编码控制技术和装置,将时刻编码信息加载到激光脉冲序列,再通过激光发射系统将该序列发送至接收端,实现时码信息的远距离传递,实现远距离空间系统时差测量和比对。本发明控制精度达到皮秒量级。通过控制激光脉冲在延迟光路中的多次往返,提高脉冲编码阶数,缩短延迟光路长度。本发明涉及的外部控制光路,不影响激光器的工作稳定。(The invention belongs to the technical field of long-distance time transmission of space laser pulses, and discloses a laser pulse position coding control method, a control system and optical communication equipment. The invention codes the time information, loads the time coding information into a laser pulse sequence through the laser pulse modulation coding control technology and the device, and then sends the sequence to a receiving end through a laser emission system, thereby realizing the remote transmission of time code information and realizing the time difference measurement and comparison of a remote space system. The control precision of the invention reaches picosecond magnitude. By controlling the multiple round trip of the laser pulse in the delay optical path, the pulse coding order is improved, and the length of the delay optical path is shortened. The external control light path does not influence the working stability of the laser.)

1. A laser pulse position coding control method is characterized by comprising the following steps: the polarization state of the laser pulse output by the laser is selectively controlled, and the selected laser pulse is input into the delay light path, so that the specific time information is loaded by the position coding of the laser pulse.

2. The laser pulse position coding control method according to claim 1, wherein the specific time information is time information of a first laser pulse of a pulse sequence or other user information.

3. The laser pulse position coding control method of claim 1, further comprising:

firstly, laser pulses pass through a first polarizer, enter a pulse modulation coding control light path, pass through a Faraday isolator and a half wave plate, and are reflected by a second polarizer after the polarization direction is rotated by 90 degrees;

secondly, controlling the polarization state of the laser pulse by an optical switch consisting of the quarter-wave plate and the Pockels cell, rotating the polarization state by 90 degrees again, reflecting the laser pulse by a first total reflector, and detecting and monitoring the laser pulse leaked by an optical detector;

thirdly, the laser pulse with the polarization state of the laser pulse rotated enters an optical delay light path consisting of a second total reflector, a total reflector and a one-dimensional translation stage; the laser pulse is locked on a delay optical path and goes back and forth for 1 to n times; when the laser pulse reaches the preset delay time, controlling the quarter-wave plate and the Pockels cell; the optical switch is composed to change the polarization state of the laser pulse again, so that the polarization state is rotated by 90 degrees;

and fourthly, after the polarization state is rotated by 90 degrees in the third step, the laser pulse is reflected by the second polarizer and reversely passes through the half wave plate and the Faraday isolator, the polarization state of the laser pulse is not changed, and the laser pulse is reflected by the first polarizer and enters a subsequent laser transmission light path.

4. The laser pulse position coding control method according to claim 3, wherein in the first step, the Faraday rotator is used in combination with a half-wave plate to achieve a 90 ° rotation of the polarization state of the incident laser pulse.

5. The laser pulse position coding control method according to claim 3, wherein in the third step, the optical delay time is determined by both the number of round trips and the delay optical path length; the delay optical path is realized by increasing the transmission optical path of the laser pulse.

6. The laser pulse position coding control method according to claim 3, wherein in the third step, the laser pulse position coding is first-order and multi-order position coding, and the multi-order position coding is determined by the round trip times of the laser pulse in the delay optical path; the optical switching frequency is 10Hz-300 KHz.

7. The laser pulse position coding control method according to claim 1, wherein in the first step to the fourth step, the laser pulse is a nanosecond laser pulse, a picosecond laser pulse or a femtosecond laser pulse, and the width is 10ns-100 fs; the laser pulse wavelength is 532nm, 1064nm or 1550 nm; the laser pulse frequency is 10Hz-300 KHz.

8. A laser pulse position code control system for implementing the laser pulse position code control method according to any one of claims 1 to 7, wherein the laser pulse position code control system comprises: a first polarizer;

laser pulses emitted by the laser device pass through the first polarizer, enter the pulse modulation coding control optical path, pass through the Faraday isolator and the half-wave plate, and are reflected by the second polarizer after the polarization direction is rotated by 90 degrees;

an optical switch composed of a quarter-wave plate and a Pockels cell controls the polarization state of the laser pulse, rotates 90 degrees again, the laser pulse is reflected by a first total reflector, and meanwhile, an optical detector detects and monitors the laser pulse which is leaked out;

under the condition that the coding state is not modulated, the polarization state of the laser pulse is not changed by the optical switch, the laser pulse reversely passes through the Faraday isolator and the half wave plate after being reflected by the first holophote, the polarization direction is not rotated, the emergent laser pulse is reflected because the polarization direction is vertical to the transmission direction of the first polarizer and enters a next-stage output light path through the third holophote;

for the laser pulse needing to be modulated, the optical switch controls the laser pulse to enable the polarization state to rotate by 90 degrees, the laser pulse enters an optical delay light path consisting of a second total reflector, the total reflector and a one-dimensional translation stage after being reflected by a first total reflector to generate delay codes, and the delay time is determined by the optical path difference of the light path;

the laser pulse after delay coding passes through the first polarizer in polarization state and is reflected by the third total reflector to enter the next stage of output light path.

9. The laser pulse position-coding control system of claim 8, wherein the first polarizer and the second polarizer are each a glan prism, a brewster angle polarizer, or a thin film polarizer;

the light-on light is a single crystal pockels cell or a double crystal pockels cell; the photodetector is a silicon photodetector, a photomultiplier tube or an InGaAs detector.

10. An optical communication device implementing the laser pulse position coding control method according to any one of claims 1 to 7.

Technical Field

The invention belongs to the technical field of long-distance time transmission of space laser pulses, and particularly relates to a laser pulse position coding control method, a control system and optical communication equipment.

Background

The laser Pulse position coding (PPM) technology is a technology for realizing information coding loading on a Pulse sequence by controlling the interval of laser pulses, i.e. the time sequence position of a single or a plurality of laser pulses in the laser Pulse sequence. The laser pulse position modulation technology is widely applied to the field of laser communication, including fiber laser communication and space laser communication, and aims to pursue communication speed. The modulated pulse sequence is usually generated by direct modulation of a laser.

If there are n bits of signal, PPM technique can load the n bits on a pulse, and read the data information by the relative position of the pulse, where the pulse position is 2ⁿThis modulation is repeated every time T, which is a different possibility (time-shifted raw data), thus making the transmission rate "n/T" (bits/sec). Pulse position modulation is widely used mainly in optical communication systems because of the problem of little to no multipath interference in optical communication systems.

In the technical field of long-distance time transmission of space laser pulses, the laser pulses are required to be as narrow as possible, so that the laser pulse time measurement precision is improved, and meanwhile, the laser single pulse energy is required to be as large as possible, so that the laser transmission distance is improved. The technical field has high requirements on the laser, so that the laser can keep stable light emitting frequency, the laser pulse jitter is reduced, the stability and the reliability of the laser can be improved, and the time transfer precision can be improved. Particularly, for a high-power narrow pulse laser, the light emitting frequency is not allowed to fluctuate in a large range, otherwise, the damage is caused, the requirement on the pulse time sequence is strict, and the pulse sequence generated by directly modulating the laser is limited. This presents a technical hurdle to the time transfer in the deep space of solar systems at great distances, especially hundreds of millions of kilometers.

The pulse laser used in the present space laser pulse long-distance time transmission technology outputs laser pulse frequency which is usually fixed and has fixed pulse interval between laser pulses. The loading and transmission of time code information cannot be realized, and measurement data must be exchanged by other technical methods such as microwave and the like.

Through the above analysis, the problems and defects of the prior art are as follows:

(1) in the prior art, precise time transmission and time code information transmission cannot be realized through the same laser link.

(2) In the prior art, the long-distance transmission performance of time code information is poor; and the pulse position and time cannot be strictly controlled, and the control precision is low. In the prior art, a laser is directly modulated to meet communication requirements, the requirement on the precision of a laser pulse time sequence is not high, and an effective control method is lacked.

(3) The prior art influences the working stability of a laser, and easily causes the influence of laser pulse jitter on laser time code and measurement precision.

The difficulty in solving the above problems and defects is: the difficulty lies in that the laser pulse transmission speed is high, and high requirements are provided for the synchronous laser signal detection and control speed. The pulse position encoding precision and high-precision control are difficult.

The significance of solving the problems and the defects is as follows: the method of the invention mainly solves the problem of PPM modulation and control of the laser pulse sequence outside the laser. According to the requirement, the method and the control system can generate first-order pulse position coding and multi-order coding. The pulse position delay precision is determined by the length of a delay optical path, and the high-order coding delay interval is integral multiple of the length of the delay optical path, so that the pulse position delay precision is convenient for accurate measurement and resolution.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a laser pulse position coding control method, a control system and optical communication equipment.

The invention is realized in such a way that a laser pulse position coding control method comprises the following steps:

the polarization state of the laser pulse output by the laser is selected, and the selected laser pulse is input into the delay light path, so that the specific time information is loaded by the position coding of the laser pulse.

Further, the specific time information is time information of a first laser pulse of the pulse sequence or other user information.

Further, the laser pulse position coding control method further comprises the following steps:

firstly, laser pulses pass through a first polarizer, enter a pulse modulation coding control light path, pass through a Faraday isolator and a half wave plate, and are reflected by a second polarizer after the polarization direction is rotated by 90 degrees;

secondly, controlling the polarization state of the laser pulse by an optical switch consisting of the quarter-wave plate and the Pockels cell, rotating the polarization state by 90 degrees again, reflecting the laser pulse by a first total reflector, and detecting and monitoring the laser pulse leaked by an optical detector;

thirdly, the laser pulse with the polarization state of the laser pulse rotated enters an optical delay light path consisting of a second total reflector, a total reflector and a one-dimensional translation stage; the laser pulse is locked on a delay optical path and goes back and forth for 1 to n times, path delay is generated once every time the laser pulse goes back and forth, and the specific delay time is determined by the length of the delay optical path; when the laser pulse reaches the preset delay time, controlling the quarter-wave plate and the Pockels cell; the optical switch is composed to change the polarization state of the laser pulse again, so that the polarization state is rotated by 90 degrees;

and fourthly, after the polarization state is rotated by 90 degrees in the third step, the laser pulse is reflected by the second polarizer and reversely passes through the half wave plate and the Faraday isolator, the polarization state of the laser pulse is not changed, and the laser pulse is reflected by the first polarizer and enters a subsequent laser transmission light path.

Further, in the first step, the faraday rotator is used in combination with a half-wave plate to realize 90 ° rotation of the polarization state of the incident laser pulse.

Further, in the third step, the optical delay time is determined by the round trip times and the delay optical path length; the delay optical path is realized by increasing the transmission optical path of the laser pulse.

Further, in the third step, the laser pulse position code is a first-order and multi-order position code, and the multi-order position code is determined by the round-trip times of the laser pulse in the delay optical path; the optical switching frequency is 10Hz-300 KHz.

Further, in the first step to the fourth step, the laser pulse is a nanosecond laser pulse, a picosecond laser pulse or a femtosecond laser pulse, and the width of the laser pulse is 10ns-100 fs; the laser pulse wavelength is 532nm, 1064nm or 1550 nm; the laser pulse frequency is 10Hz-300 KHz.

Another object of the present invention is to provide a system for implementing laser pulse position coding control, comprising: a first polarizer;

laser pulses emitted by the laser device pass through the first polarizer, enter the pulse modulation coding control optical path, pass through the Faraday isolator and the half-wave plate, and are reflected by the second polarizer after the polarization direction is rotated by 90 degrees;

an optical switch composed of a quarter-wave plate and a Pockels cell controls the polarization state of the laser pulse, rotates 90 degrees again, the laser pulse is reflected by a first total reflector, and meanwhile, an optical detector detects and monitors the laser pulse which is leaked out;

under the condition that the coding state is not modulated, the polarization state of the laser pulse is not changed by the optical switch, the laser pulse reversely passes through the Faraday isolator and the half wave plate after being reflected by the first holophote, the polarization direction is not rotated, the emergent laser pulse is reflected because the polarization direction is vertical to the transmission direction of the first polarizer and enters a next-stage output light path through the third holophote;

for the laser pulse needing to be modulated, the optical switch controls the laser pulse to enable the polarization state to rotate by 90 degrees, the laser pulse enters an optical delay light path consisting of a second total reflector, the total reflector and a one-dimensional translation stage after being reflected by a first total reflector to generate delay codes, and the delay time is determined by the optical path difference of the light path;

the laser pulse after delay coding passes through the first polarizer in polarization state and is reflected by the third total reflector to enter the next stage of output light path.

Further, the first polarizer, the second polarizer are each a Glan prism, a Brewster's angle polarizer, or a thin film polarizer.

Further, the light-opening light is a single crystal pockels cell or a double crystal pockels cell; the photodetector is a silicon photodetector, a photomultiplier, an InGaAs detector

The invention also aims to provide optical communication equipment for implementing the laser pulse position coding control method, which is used for long-distance spatial laser pulse long-distance time transmission.

By combining all the technical schemes, the invention has the advantages and positive effects that:

the invention relates to laser pulse time measurement, and the pulse time information is loaded on a laser beam through modulation coding to generate a laser pulse sequence containing time code information. The invention is used for realizing precise time synchronization and high-precision time service between the free space ground and the spacecraft or the spacecraft.

The device can be used for a space laser precise time transmission system, the control system encodes the time information, and the time code encoding information is loaded to a laser pulse sequence by the laser pulse modulation encoding control technology and the device, and the sequence is sent to a receiving end by a laser emission system, so that the long-distance transmission of the time code information is realized.

The pulse position time of the invention can be strictly controlled, and the control precision can reach picosecond magnitude.

Through multiple round-trip control of laser pulse, the pulse coding order can be further improved, and the length of a delay optical path can be shortened.

The external control light path does not influence the working stability of the laser, and is beneficial to reducing the influence of laser pulse jitter on laser time code and measurement precision.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.

Fig. 1 is a flowchart of a laser pulse position coding control method according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a laser pulse position coding control system provided in embodiment 1 of the present invention.

Fig. 3 is a schematic diagram of a laser pulse position coding control system provided in embodiment 2 of the present invention.

In the figure: 1. a first polarizer; 2. a Faraday isolator; 3. a half wave plate; 4. a second polarizer; 5. a quarter wave plate; 6. pockels cell; 7. a first total reflection mirror; 8. a light detector; 9. a second total reflection mirror; 10. a holophote and a one-dimensional translation stage; 11. a third total reflection mirror; 12. a laser.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.