[0024] The present invention will be further described below in conjunction with the embodiments and drawings, but the protection scope of the present invention should not be limited by this.
[0025] See first figure 1 , figure 2 with image 3 , figure 1 It is a schematic diagram of the structure of the device for maintaining the polarization direction and energy stability of the low repetition rate short pulse optical signal of the present invention, figure 2 Is a schematic diagram of the structure of the feedback unit of the present invention, image 3 It is a schematic diagram of the structure of the control unit of the present invention. It can be seen from the figure that the device of the present invention for maintaining the polarization direction and energy stability of the low repetition rate short pulse optical signal consists of a continuous fiber laser 1, an optical pulse generator 2, a polarization control unit 3, an analyzer 4, a fiber splitter 5, and feedback Unit 6, digital controller 7, and signal synchronizer 8. The polarization control unit 3 is composed of a polarization control module 3-1 and a drive circuit 3-2 in turn. The drive circuit 3-2 is provided by the polarization control module 3-1 Working voltage, the feedback unit 6 is composed of photodetector 6-1, integrating circuit 6-2, high-speed electric amplifier 6-3, and high-speed acquisition card 6-4 in sequence. The connection relationship is: continuous along the main optical path Fiber laser 1, optical pulse generator 2, polarization control unit 3, analyzer 4 and fiber splitter 5, said fiber splitter 5 divides the input light into two beams: the first beam 501 is the main beam, which is connected To the subsequent laser device, the second beam is the monitoring beam 502, and the monitoring end loop is composed of the monitoring beam 502 of the optical fiber splitter 5, the feedback unit 6 and the digital controller 7 connected in sequence, and the digital controller 7 is connected to the The input port 3-201 of the drive circuit is connected. The first signal output terminal 801 of the signal synchronizer 8 is connected to the trigger terminal 201 of the optical pulse generator, and the second signal output terminal 802 of the signal synchronizer 8 is connected to the trigger terminal 6 of the high-speed acquisition card 6-4 in the feedback unit 6 401.
[0026] The continuous laser signal generated by the continuous fiber laser 1 is input to the optical pulse generator 2. When the trigger pulse signal output by the first signal output terminal 801 of the signal synchronizer 8 is input to the trigger terminal 201 of the optical pulse generator The optical pulse generator 2 outputs an optical pulse signal, and the pulse width of the optical pulse signal is determined by the pulse width of the trigger pulse signal and is in the range of 1 ns to 10 μs. The optical pulse signal passes through the polarization control module 3-1 and the analyzer 4 in turn, and then is divided into two paths by the fiber splitter 5, one path 501 is used as the main optical path to connect to the subsequent laser device, and the other path 502 is used as the monitoring light input Monitor the light path. Observe the pulse energy of the output light of the monitoring optical path 502, and control the polarization control module 3-1 according to the magnitude of the energy of the monitoring end 502, so that the optical pulse signal before input to the analyzer 4 is linearly polarized light and the polarization direction is the same The analyzer has the same polarization direction, so that the energy of the optical pulse output by the monitoring terminal 502 is kept near the maximum value. In this way, the energy of the output optical pulse of the analyzer 4 is stabilized at the maximum value, and the polarization direction is always maintained at the analyzer. In the analyzer 4 direction. The optical pulse output by the monitoring terminal 502 is first received by the photodetector 6-1 and converted into an electrical pulse signal with the same pulse width as that of the optical pulse. The electrical pulse energy is proportional to the optical pulse energy, and the pulse width is In the range of 1ns to 10μs. The electrical pulse signal is input to the integrating circuit 6-2, which expands the pulse width of the electrical pulse signal, and the pulse width of the electrical pulse signal after the expansion is on the order of 10 μs. Since the signal amplitude of the stretched electric pulse has decreased, a high-speed electric amplifier 6-3 is used to amplify the amplitude of the stretched electric pulse, and then the amplified and stretched electric pulse signal is input to the high-speed acquisition card 6-4 for collection . The second output terminal 802 of the signal synchronizer 8 inputs a trigger signal with the same repetition frequency as the short pulse optical signal to the trigger input terminal 6-401 of the high-speed acquisition card 6-4. The amplified and expanded electrical pulse signal enters the high-speed acquisition card 6-4 in advance. After the high-speed acquisition card 6-4 receives the trigger signal, it starts to prepare to acquire the amplified and expanded electrical pulse signal. After the amplified and expanded electrical pulse signal enters the high-speed acquisition card 6-4, the high-speed acquisition card 6-4 collects a certain amount in a certain time interval within a certain time interval of the energy time waveform of the expanded electrical pulse signal Data points. Then input these data points into the digital controller 7, and then accumulate the data of the received data points in the digital controller 7, and use the accumulated value as the energy of the monitoring light pulse. The digital controller 7 compares the energy of the obtained monitoring light pulse with the energy of the previous monitoring light pulse, and then makes a corresponding logical judgment, and then sends a control signal to the drive circuit 3-2, and the drive circuit 3 -2 Provide a suitable operating voltage to the polarization control module 3-1 according to the received control signal, so that the polarization direction of the low repetition rate short pulse optical signal input to the analyzer 4 is maintained in the analyzer 4 In the analyzer direction of 4, the energy of the optical pulse signal output by the analyzer is stabilized at the maximum value, and the polarization direction is consistent with the analyzer's analyzer direction.
[0027] The photodetector 6-1 adopts a high-speed photodetector, which converts a short pulse optical signal of 3 ns into an electrical pulse signal of the same pulse width. The integration circuit 6-2 uses a current integration circuit, and the specific structure is as follows Figure 4 Shown. The negative pole of the photodetector 6-1 is connected to the positive pole 6-2-1 of the DC power supply through a 50 ohm resistor 6-2-2. The photodetector 6-1 converts the optical pulse signal into an electrical pulse signal, and the converted current signal is directly The capacitor 6-2-3 is charged, and at the same time, a discharge circuit is formed with the resistor 6-2-4 connected in parallel with the capacitor, so that the pulse width of the electric pulse signal is expanded to the order of 10 μs after passing through the integrating circuit. The discharge time constant is τ=RC, where R is the resistance value of the resistor 6-2-4, and C is the capacitance value of the capacitor 6-2-3. The discharge time constant τ reflects the length of the discharge time of the capacitor 6-2-4, and determines the pulse width of the electric pulse after the expansion. The longer the discharge time, the longer the pulse width of the stretched electric pulse, but since the energy of the electric pulse is constant, the longer the discharge time, the smaller the signal amplitude of the stretched electric pulse. Therefore, by changing the capacitor 6-2-3 and the resistor 6-2-4, the pulse width of the electric pulse after stretching can be changed. The high-speed electrical amplifier 6-3 is a high-bandwidth, low-drift, high-speed amplifier, which amplifies the signal after expansion so that the signal can be collected by the high-speed acquisition card 6-4.
[0028] The driving circuit 3-2 is composed of a D/A converter and an amplifier. The D/A converter is used to convert the digital signal output by the digital controller 7 into an analog signal, and the amplifier is used to amplify the analog signal. The polarization control module 3-1 provides a suitable working voltage.
[0029] For example: figure 1 A device that maintains the polarization direction and energy stability of a short pulse optical signal with a low repetition rate. The optical pulse generator 2 uses an intensity modulator. The pulse width of the optical pulse signal output by the intensity modulator is 3ns, the repetition frequency is 1Hz, and the center wavelength is 1053nm, the polarization control module 3-1 adopts the EPC-300 electronically controlled polarization controller of 0Z company, and the 100M high-speed acquisition card is used in the experiment. The digital controller 7 is composed of a computer and a microprocessor. The device is a single-chip microcomputer, and the splitting ratio of the fiber splitter 5 is 90%: 10%, of which 90% is the main light, which is connected to the follow-up device, and 10% is the monitoring light.
[0030] In order to illustrate the effect of the present invention, the following experiments were carried out:
[0031] A manual polarization controller is connected between the optical pulse generator 2 and the electronically controlled polarization controller 3-1. The polarization state of the input optical pulse signal is changed by adjusting the manual polarization controller, and the magnitude of the optical pulse energy output by the 90% port of the fiber splitter is observed. When the device for maintaining the polarization direction and output energy of the low repetition rate short pulse optical signal is not working, because the polarization state and polarization direction of the optical signal before input to the analyzer change with the adjustment of the manual polarization controller Therefore, the optical pulse energy output by the main optical path also changes with the adjustment of the manual polarization controller. The energy of the optical pulse output from the main optical path can be adjusted to the maximum by the manual adjustment of the polarization controller, indicating that the polarization state of the optical pulse input to the analyzer 4 is basically the same as that of the analyzer 4. At this time, 90% port output is recorded The energy value of the light pulse. Then, the device for maintaining the polarization direction and output energy of the short pulse optical signal with a low repetition rate is controlled to control the polarization state of the optical pulse signal. It is observed that when the device that maintains the polarization direction and output energy of the low repetition rate short pulse optical signal is working, the manual polarization controller is used to make the polarization state of the optical pulse signal in the main optical path abrupt, and the main optical path outputs the optical pulse. The energy can be automatically adjusted and restored to the maximum value of the optical pulse energy previously observed in the main optical path in a short time, and maintained at the maximum value of the optical pulse energy, indicating that the device has maintained the output light polarization direction and output energy The role of. A total of 37 experiments were carried out in 13 groups. The experiment showed that after the polarization direction of the optical pulse signal of the main optical path changes suddenly, the device of the present invention can maintain the stability of the polarization direction and output energy of the low repetition rate short pulse optical signal.
[0032] It can be seen that the device of the present invention can compensate for the slow drift of the polarization state of the optical signal in the optical fiber caused by the environmental temperature and stress, and ensure the polarization direction and output energy of the optical pulse signal output by the low repetition rate short pulse high power fiber laser system. stable.
