A testing device and method for long-term stability of pulse laser repetition frequency and pulse width

Abstract

The present invention discloses a test device and method for the long-term stability of the pulse repetition frequency and pulse width of a pulsed laser. The device includes a beam splitter, two high-speed detectors, and a high-speed acquisition card with an adjustable post-trigger delay time. The method first divides the pulsed laser into two beams of laser through the beam splitter. One beam of laser serves as a trigger signal, and the other beam of laser serves as a detection signal. The two high-speed detectors receive them respectively and transmit them to the trigger channel and the detection channel of the high-speed acquisition card. Then, by setting the delay time and acquisition time of the detection channel, the detection channel only records and saves the detection data when the pulse passes through. Finally, through post-data processing, the long-term stability of the pulse repetition frequency and pulse width of the pulsed laser within the test time can be obtained. The advantages of the present invention are as follows: 1) It realizes the simultaneous measurement of the pulse repetition frequency and pulse width of the pulsed laser; 2) It realizes the preservation of the original data for the long-term test of the pulse repetition frequency and pulse width of the pulsed laser; 3) It reduces the amount of original data to be saved in the long-term test.

Description

Technical Field

[0001] The present invention belongs to the technical field of lasers, and particularly relates to a test device and method for the long-term stability of the pulse repetition frequency and pulse width of pulsed lasers. Background Art

[0002] With the development of lidar technology, the demand for short-pulse lasers, especially sub-nanosecond pulse lasers, in fields such as three-dimensional mapping and atmospheric detection is becoming increasingly strong. Among them, the long-term stability of the pulse repetition frequency and pulse width of pulsed lasers is an important parameter for evaluating pulsed lasers. In common test methods, generally a single photodetector is directly used to receive the laser, and the oscilloscope's measurement function is used to measure the statistical values of the fluctuations in the pulse repetition frequency and pulse width of the pulsed laser. This test method is simple and effective, but it cannot record long-term original detection data and cannot save the original data. Using a data acquisition card instead of an oscilloscope to record and save data can overcome this shortcoming. However, for short-pulse lasers, their pulse widths are short and the duty cycles are high, and a high sampling rate is required to ensure that the time-domain pulse information can be correctly recorded, which will inevitably greatly increase the amount of test data to be saved. Especially for the long-term stability test of the pulse repetition frequency and pulse width of pulsed lasers, the amount of original data is proportional to the test time, which will further increase the difficulty of saving the original measurement data. Summary of the Invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a test device and method for the long-term stability of the pulse repetition frequency and pulse width of pulsed lasers. By using a high-speed data acquisition card with an adjustable post-trigger delay time, it records and saves the original detection data of a specified time length that only contains laser pulses, and can simultaneously obtain the pulse repetition frequency and pulse width information of the pulsed laser, solving the problem of excessive amount of original detection data in the long-term stability test of the pulse repetition frequency and pulse width of pulsed lasers at high sampling rates.

[0004] The device of the present invention is as Figure 1 shown, and includes a pulsed laser 1, a beam splitter 2, a first high-speed photodetector 3, a second high-speed photodetector 4, a high-speed data acquisition card 5, and a data storage module 6. Among them, the pulsed laser 1 is used as the pulsed laser light source to be tested, and outputs periodic optical pulses to the beam splitter 2. A part of the split pulsed laser is received by the first high-speed photodetector 3, and the other part is received by the second high-speed photodetector 4. The first high-speed photodetector 3 is connected to the trigger channel of the high-speed data acquisition card 5 as a trigger signal, and the second high-speed photodetector 4 is connected to the detection channel of the high-speed data acquisition card 5 as a detection signal. Finally, the detection data is saved by the data storage module 6, and the pulse repetition frequency, pulse width, and their long-term stability of the pulsed laser are obtained through post-data processing.

[0005] In the said device, the pulsed laser 1 outputs periodic pulsed laser light;

[0006] In the said device, the high-speed acquisition card 5 is a high-speed acquisition card with an adjustable post-trigger delay time;

[0007] The steps of the method for testing the long-term stability of the pulse repetition frequency and pulse width of a pulsed laser are as follows:

[0008] 1. The optical pulse emitted by the pulsed laser 1 is split into two beams by the beam splitter 2;

[0009] 2. The two split optical pulses are respectively received by the first high-speed photodetector 3 and the second high-speed photodetector 4, and their electrical signals are respectively used as the trigger signal and the detection signal of the high-speed acquisition card 5;

[0010] 3. Set the post-trigger delay time t 1 and the detection signal acquisition time t 2 of the high-speed acquisition card 5 according to the estimated laser pulse repetition frequency and pulse width, so as to ensure that the detection signal corresponding to the optical pulse duration can be collected and saved;

[0011] 4. Use the data storage module 6 to save the detection signal, and perform post-processing on the detection signal to calculate the optical pulse delay t 2 within the acquisition time t 3 and the optical pulse width w pulse , then the pulse period is t 2 +t 3 , and the corresponding repetition frequency is f = 1 / (t 2 +t 3 );

[0012] 5. According to the laser pulse width w pulse and the repetition frequency f obtained from the long-term test, the long-term stability of the pulse repetition frequency and pulse width of the pulsed laser can be obtained.

[0013] The present invention realizes the long-term stability test of the pulse repetition frequency and pulse width of a pulsed laser and the acquisition and storage of the original detection data. By setting the post-trigger delay time and the detection signal acquisition time of the high-speed acquisition card, the present invention realizes the efficient preservation of the original data during the long-term stability test of the pulse repetition frequency and pulse width of a pulsed laser. Especially for short-pulse lasers, the original detection data can be saved at a high sampling rate, and the amount of data to be saved can be reduced.

[0014] The purpose of the present invention is to provide a device and method for testing the long-term stability of the pulse repetition frequency and pulse width of a pulsed laser, which can be applied to the long-term stability test of the pulse repetition frequency and pulse width of a pulsed laser. The beneficial effects of the present invention are as follows:

[0015] 1) Realize the simultaneous measurement of the pulse repetition frequency and pulse width of a pulsed laser;

[0016] 2) The original data preservation for the long-term testing of the pulse repetition frequency and pulse width of pulsed lasers is realized;

[0017] 3) The amount of original data to be preserved in long-term testing is reduced; Description of the Drawings

[0018] Figure 1 This is a schematic structural diagram of the device of the present invention. In the figure: 1 - pulsed laser; 2 - beam splitter; 3 - first high-speed photodetector; 4 - second high-speed photodetector; 5 - high-speed acquisition card; 6 - data storage module. Detailed Implementation Manner

[0019] The implementation manner of the present invention will be described in detail below in conjunction with the drawings and an example of the long-term stability testing of the pulse repetition frequency and pulse width of a 1064 nm-band microchip passively Q-switched pulsed laser.

[0020] The main devices used in the present invention are described as follows:

[0021] 1. Pulsed laser 1: A self-made microchip passively Q-switched pulsed laser with a central wavelength of 1064.2 nm, a pulse repetition frequency of about 100 kHz, and a pulse width of about 300 ps.

[0022] 2. Beam splitter 2: A laser beam splitter with a beam splitting ratio of 50:50.

[0023] 3. First high-speed photodetector 3 and second high-speed photodetector 4: Silicon free-space photodetector DET025A / M from Thorlabs, with a detection bandwidth of 2 GHz.

[0024] 4. High-speed acquisition card 5: High-speed acquisition card ATS9373 from AlazarTech, with a maximum single-channel sampling rate of 4 GHz.

[0025] 5. Data storage module 6: A personal computer, connected to the high-speed acquisition card through a Thunderbolt 3 interface.

[0026] The schematic diagram of the method of the present invention is as Figure 1 shown. The specific situation is described as follows:

[0027] 1. The collimated laser emitted by the pulsed laser 1 is split into two beams by the beam splitter 2, with a beam splitting ratio of 50:50;

[0028] 2. The two split optical pulses are respectively aligned with the first high-speed photodetector 3 and the second high-speed photodetector 4, and it is ensured that the light spots are completely within the photosensitive surfaces of the two detectors. These two electrical signals serve as the trigger signal and the detection signal of the high-speed acquisition card 5 respectively;

[0029] 3. The estimated laser pulse repetition rate and pulse width are 100 ± 5 kHz and 300 ± 100 ps respectively. Therefore, the post-trigger delay time t of the high-speed acquisition card 5 is set 1 to be 9.522 μs, and the detection signal acquisition time t 2 is 1.002 μs to ensure that the detection signals corresponding to the optical pulse duration can be acquired and saved;

[0030] 4. The data storage module 6 is used to save the detection signals. At this time, compared with storing all detection signals completely, the storage space is reduced by about 9 times; the detection signals are post-processed, and the optical pulse delay t 2 within the acquisition time t 3 and the optical pulse width w pulse are calculated. Then the pulse period is t 2 + t 3 , and the corresponding repetition rate is f = 1 / (t 2 + t 3 );

[0031] 5. According to the laser pulse width w pulse and repetition rate f obtained from long-term tests, the long-term stability of the repetition rate and pulse width of this pulsed laser can be obtained.

[0032] In summary, this device can achieve the test of the long-term stability of the repetition rate and pulse width of pulsed lasers. Also, because the high-speed acquisition card with adjustable post-trigger delay time used in the present invention can collect and save the detection signals only containing the pulse duration by setting the post-trigger delay time and signal acquisition time, the amount of original data to be saved can be greatly reduced while ensuring a high sampling rate.

Claims

1. A test method for the long-term stability of the pulse repetition frequency and pulse width of a pulsed laser. The test device used includes a pulsed laser (1), a beam splitter (2), a first high-speed photodetector (3), a second high-speed photodetector (4), a high-speed acquisition card (5), and a data storage module (6). It is characterized in that: The pulsed laser (1) serves as the pulsed laser light source to be tested, outputting periodic optical pulses to the beam splitter (2). One part of the split pulsed laser is received by the first high-speed photodetector (3), and the other part is received by the second high-speed photodetector (4). The first high-speed photodetector (3) is connected to the trigger channel of the high-speed acquisition card (5) as a trigger signal, and the second high-speed photodetector (4) is connected to the detection channel of the high-speed acquisition card (5) as a detection signal. Finally, the detection data is saved by the data storage module (6), and the repetition frequency and pulse width of the pulsed laser, as well as its long-term stability, are obtained through data post-processing. The steps of this test method are as follows: 1) The optical pulses emitted by the pulsed laser (1) are split into two beams by the beam splitter (2). 2) The two split optical pulses are respectively received by the first high-speed photodetector (3) and the second high-speed photodetector (4), and their electrical signals are respectively used as the trigger signal and the detection signal of the high-speed acquisition card (5). 3) Set the post-trigger delay time t 1 and the detection signal acquisition time t 2 of the high-speed acquisition card (5) according to the estimated laser pulse repetition frequency and pulse width, so as to ensure that the detection signals corresponding to the optical pulse duration can be collected and saved; 1 and the detection signal acquisition time t 2 ; 4) Use the data storage module (6) to save the detection signal, perform post-data processing on the detection signal, and calculate the acquisition time t 2 The delay t from the start of acquisition to the detection of the peak of the optical pulse within 3 and the optical pulse width w pulse , then the pulse period is t 1 +t 3 , and the corresponding repetition frequency is f = 1 / (t 1 +t 3 ); 5) Based on the laser pulse width w obtained from long-term testing pulse and the repetition rate f, the long-term stability of the repetition rate and pulse width of the pulsed laser can be obtained.

2. A test method for the long-term stability of the pulse repetition frequency and pulse width of a pulsed laser according to claim 1, It is characterized in that: The pulsed laser (1) outputs periodic pulsed laser, and the duty cycle of the optical pulse is less than 50%.

3. A test method for the long-term stability of the pulse repetition frequency and pulse width of a pulsed laser according to claim 1, It is characterized in that: The high-speed acquisition card (5) is a high-speed acquisition card that meets the requirements of laser pulse width detection, and the time delay for acquisition after triggering is adjustable arbitrarily.

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