CN-116358716-B - Ultrashort pulse synchronous testing device and method based on optical Kerr effect

CN116358716BCN 116358716 BCN116358716 BCN 116358716BCN-116358716-B

Abstract

An ultrashort pulse synchronous test device and method based on optical Kerr effect. The high power density ultrashort pulses to be synchronized are passed through the optical kerr medium and then undergo an induced birefringence effect which instantaneously changes the polarization characteristics of the reference beam, and the synchronization between the ultrashort pulses is measured by the amplitude or phase change of the reference signal pulses. The method can realize synchronous measurement of the large-angle ultrashort pulse at the target point, and has the advantages of high measurement accuracy, good repeatability, high stability and the like.

Inventors

FAN WEI
ZHANG TIANYU
XU YINGMING
WANG XIAOCHAO
LIU CHENG
SUN MINGYING
ZHU JIANQIANG
ZHANG SHENGJIA

Assignees

中国科学院上海光学精密机械研究所

Dates

Publication Date: 20260512
Application Date: 20230423

Claims (9)

1. An ultrashort pulse synchronous test device based on optical kerr effect is characterized by comprising: the external injection signal light (1) is picosecond pulse light or femtosecond pulse light as reference light; a polarizer (2) for adjusting the polarization direction of the external injection signal light (1); A delay line (3) for generating a spatial delay, adjusting the time delay of the externally injected signal light (1), and being incident on an optical kerr medium (4); An optical Kerr medium (4), wherein 2 or more synchronous pulses are incident to the optical Kerr medium (4) to generate an optical Kerr effect, so that the polarization state of the externally injected signal light (1) is changed; An analyzer (5), wherein the optical axis direction of the analyzer (5) is perpendicular to the optical axis direction of the polarizer (2) and is used for detecting the optical kerr effect; A detector (6) for detecting the pulse intensity and phase distribution after transmission or reflection by the analyzer (5); The control and data processing module (7) is used for controlling the detector (6) and all delay lines, processing the acquired data, acquiring delay information between different pulses to be synchronized and the external injection signal light (1), and synchronizing with a plurality of pulses to be synchronized of the pulses to be synchronized; The N-beam pulse to be synchronized (11) is N-beam pulse to be synchronized, namely picosecond or femtosecond pulse light, wherein N is more than or equal to 2, and the included angle between the N-beam pulse to be synchronized and the external injection signal light (1) is in the range of (0, pi); the first delay line (9), the N delay line (12) is used for generating space delay and is used for adjusting the time delay of the first beam of pulses (8) to be synchronized and the N beam of pulses (11) to be synchronized respectively; The first half wave plate (10), the N half wave plate (13) are used for controlling the first beam of the pulse to be synchronized (8) after passing through the first delay line (9), the N delay line (12), the polarization direction of the N beam of the pulse to be synchronized (11) is then incident into the optical Kerr medium (4) to generate the optical Kerr effect.
2. Ultrashort pulse synchronous test device based on optical kerr effect according to claim 1, wherein the detector (6) is a photocell or spot intensity detector or a phase measuring instrument module.
3. Ultrashort pulse synchronous test device based on optical kerr effect according to claim 2, characterized in that when the detector (6) is a phase detector module, the phase detector module comprises a wavefront modulator module (14) and a spot detector (15); a wave front modulator module (14) for phase modulating the externally injected signal light (1); and the light spot detector (15) is used for recording the intensity distribution of the externally injected signal light (1) modulated by the wave front modulator module (14).
4. An ultrashort pulse synchronous test device based on the optical kerr effect according to claim 3, wherein the wavefront modulator module (14) is a binary stepped phase wavefront modulator, a ternary stepped phase wavefront modulator, a ten-element stepped phase wavefront modulator, a continuous phase modulator, a continuous amplitude phase modulator or a pure amplitude type wavefront modulator.
5. The ultra-short pulse synchronous testing device based on the optical kerr effect according to claim 1, wherein the polarization axes of the polarizer (2) and the analyzer (5) are perpendicular to each other, and the polarizer (2) and the analyzer (5) are a polarizer, a polarization beam splitter prism or a nicol prism.
6. The ultrashort pulse synchronous test device based on the optical kerr effect according to claim 1, wherein the delay line (3), the first delay line (9) and the nth delay line (12) comprise four 45 ° mirrors arranged on an electric or manual displacement table.
7. The ultra-short pulse synchronous testing device based on the optical kerr effect according to claim 1, wherein the optical kerr medium is carbon disulfide, fused quartz, bismuthate glass, tellurite glass, nitrobenzene, chalcogenide glass, silicate glass, heavy flint glass, neodymium glass.
8. An ultrashort pulse synchronous test method based on optical Kerr effect is characterized by comprising the following steps: after the external injection signal light (1) sequentially passes through the polarizer (2) and the delay line (3), the external injection signal light is collimated and incident to the optical Kerr medium (4); The first beam of pulse to be synchronized (8) enters a first half wave plate (10) after passing through a first delay line (9), rotates the first half wave plate (10) to form 45 degrees with the polarization direction of external injection signal light (1), enters an optical kerr medium (4) to generate an optical kerr effect, changes the polarization state when the external injection signal light (1) passes through the optical kerr medium (4), and then enters an analyzer (5); the detector (6) is used for measuring the real-time intensity and phase space distribution of the output pulse signal after the analyzer (5), and any one of the following methods is adopted: Method 1: When the detector (6) is a photoelectric tube, the transmitted pulse or the reflected pulse of the analyzer (5) is measured in real time, and the first beam of pulses (8) to be synchronized is expressed as The externally injected signal light (1) output after reaching the analyzer is expressed as By adjusting a delay line (3) in the reference beam path to pulse the reference signal The polarization component at the photoelectric tube has the strongest intensity, namely the maximum amplitude value displayed by the oscilloscope, and the position is indicated as a position L 1 , and the delay line (3) in the reference light path is locked at the position; method 2: when the detector (6) is a light spot detector, the transmitted pulse or the reflected pulse of the analyzer (5) is measured in real time in the spatial distribution of intensity, and the first beam of pulses (8) to be synchronized is expressed as The externally injected signal light (1) output after reaching the analyzer is expressed as By adjusting a delay line (3) in the reference beam path to pulse the reference signal Due to the influence of the first beam of pulses to be synchronized (8), fringes are generated on the spot detector, the width of the fringes is maximized after adjustment, the position is denoted as L 1 , and the delay line (3) in the reference light path is locked at the position; Method 3: When the detector (6) is a phase measuring instrument module composed of a wave front modulator module (14) and a light spot detector (15), the transmitted or reflected signal light after the analyzer (5) is measured in real time for intensity and phase space distribution, and the first beam of pulses (8) to be synchronized is expressed as The externally injected signal light (1) output after reaching the analyzer is expressed as First of all by adjusting a delay line (3) in a reference optical path to pulse a reference signal The polarized component light spot Q 1 at the phase measuring instrument module has the strongest intensity, measures the phase value nearby the position, and accurately adjusts to the highest abrupt change position of the phase, generates stripes on the light spot detector due to the influence of the first beam to-be-synchronized pulse (8), makes the stripe width largest after adjustment, measures the phase value nearby the position, and finds the position with the strongest abrupt change of the stripe phase, which is denoted as the position L 1 ; The N beam of pulse to be synchronized (11) enters an N half wave plate (13) after passing through an N path of delay line (12), rotates the N half wave plate (13) to form 45 degrees with the polarization direction of external injection signal light (1), enters an optical Kerr medium (4) to generate an optical Kerr effect, changes the polarization state of the external injection signal light (1) when passing through the optical Kerr medium (4), and then enters an analyzer (5); the detector (6) is used for measuring the real-time intensity and phase space distribution of the output pulse signal after the analyzer (5), and the method is based on the following steps The selected method is selected as the following corresponding method: Method 1: when the detector (6) is a photoelectric tube, the transmitted pulse or the reflected pulse of the analyzer (5) is measured in real time, and the N-th beam to be synchronized pulse (11) is expressed as The externally injected signal light (1) output after reaching the analyzer is expressed as Pulse the reference signal through the N-th delay line (12) The polarized component at the photoelectric tube has the strongest intensity, namely the maximum amplitude value displayed by the oscilloscope, the position is indicated as a position L N , and the first beam of pulses (8) to be synchronized and the N beam of pulses (11) to be synchronized can achieve time synchronization; method 2: when the detector (6) is a light spot detector, real-time intensity space distribution measurement can be carried out on the transmitted pulse or the reflected pulse of the analyzer (5), and the Nth beam to-be-synchronized pulse (11) is expressed as The externally injected signal light (1) output after reaching the analyzer is expressed as Pulse the reference signal through the N-th delay line (12) The polarization component light spot Q N at the light spot detector has the strongest intensity, and the light spot detector has stripes due to the influence of the N-th beam to-be-synchronized pulse (11), so that the stripe width is maximized after adjustment, and the position is expressed as L N ; Method 3: When the detector (6) is a phase measuring instrument module composed of a wave front modulator module (14) and a light spot detector (15), the transmitted or reflected signal light after the analyzer (5) can be measured in real time in terms of intensity and phase space distribution, and the N-th beam to-be-synchronized pulse (11) is expressed as The externally injected signal light (1) output after reaching the analyzer is expressed as First, the N-th delay line (12) is adjusted to pulse the reference signal The polarized component light spot Q N at the phase measuring instrument module has the strongest intensity, measures the phase value near the position, accurately adjusts to the highest abrupt change position of the phase, generates stripes on the light spot detector due to the influence of the N-th beam to-be-synchronized pulse (11), ensures that the stripe width is maximum after adjustment, measures the phase value near the position, finds the position with the strongest abrupt change of the stripe phase, and indicates as a position L N , and at the moment, the first beam to-be-synchronized pulse (8) and the N-th beam to-be-synchronized pulse (11) can achieve high-precision time synchronization and accurately control the acting position of the first beam to-be-synchronized pulse and the N-th beam to-be-synchronized pulse in the optical Kerr medium to be consistent.
9. The method for synchronously testing the ultrashort pulses based on the optical kerr effect according to claim 8, wherein the steps are as follows The phase measuring method adopted by the phase measuring instrument module of the method 3 comprises the following specific steps: step 3-3-1. Calibrating the transmittance distribution of the wavefront modulator module (14) to be The wavefront distribution in front of the wavefront modulator module (14) is represented as The wavefront after passing through the wavefront modulator is represented as The wavefront is propagated to a spot detector (15) to obtain a wavefront: wherein For the distance between the wavefront modulator module (14) and the spot detector (15), Representing the free space propagation L distance of the wavefront; step 3-3-2 the spot intensity recorded by the spot detector (15) is expressed as Will be The amplitude update of (a) is expressed as Wherein Representing a square root taking operation, Representing a phase-picking operation, which is then counter-propagated to the wavefront modulator module (14) to obtain a wavefront Wherein Representing the free space back propagation of the wavefront by a distance L, and obtaining the wavefront distribution as: propagating the wavefront into the focal plane and limiting results in: wherein For the distance between the wavefront modulator module (14) and the focal plane, Is limited by small holes and then transmitted back to the wave front modulation module to obtain wave front ; Calculating an error value: wherein Representing an absolute value taking operation; Will be Assignment to Repeating the steps 3-3-1 and 3-3-2 until the error value Less than expected to result in Is the complex amplitude distribution of the wavefront to be measured.

Description

Ultrashort pulse synchronous testing device and method based on optical Kerr effect Technical Field The invention relates to the fields of ultra-short pulse synchronization, intensity measurement, phase imaging and third-order nonlinearity, in particular to a device and a method for measuring time synchronization among multiple ultra-short pulses. Background With the development of high-power ultrashort pulse technology, the problem of time synchronization between different ultrashort pulses is widely studied. For example, when a double-cone collision laser fusion ignition study is performed, a plurality of short pulses from different angles are required to bombard a target pill simultaneously, a coherent beam combining method is adopted for a high-energy clapping device to further improve peak intensity, high requirements are also provided for time synchronization among pulses, and high-precision time synchronization measurement and control are particularly important for a pumping detection experiment capable of realizing measurement of various transient processes. The common scheme for measuring the ultra-short pulse synchronization at present comprises a photoelectric tube combined oscilloscope method, a spectrum interferometry method, an optical cross-correlation method, a laser plasma method and the like. The method of combining the photoelectric tube with the oscilloscope is the most commonly used method at present, but is limited by response time and bandwidth of the photoelectric tube and the oscilloscope, and the current synchronous measurement accuracy is generally about 10 ps. The spectral interferometry method can only be used for synchronous measurement of broadband ultrashort pulses and is not suitable for synchronous measurement between angled focused pulses, considering the case of interferometry. The optical cross-correlation method utilizes the sum frequency signal intensity of two pulse signals to obtain relative delay, the accuracy of the method can reach the femtosecond level, but the method is difficult to measure complex wave fronts because of the influence of nonlinear effects. The laser plasma method is suitable for high angle beam simultaneous measurements (Qihua Zhu et al 2018 Laser Phys.Lett.15 015301), but the generation of the plasma requires laser power densities above 10 15W/cm2. Therefore, the scheme cannot simultaneously realize synchronous measurement of the ultra-short pulse with high precision and large angle at the target point by using lower energy. Disclosure of Invention Aiming at the limitation of the ultra-short pulse synchronization technology, the invention provides an ultra-short pulse synchronization test device and method based on the optical Kerr effect, which utilize the medium optical Kerr effect to judge the time delay of the synchronization pulse. After passing through the optical Kerr medium, the amplitude and phase distribution of the signal pulses have different changes, which can effectively improve the synchronization accuracy of the ultrashort pulses. The method quantifies the synchronization accuracy and can repeatedly measure the liquid optical Kerr medium. The method has the characteristics of high stability and high time synchronization precision. The technical scheme of the invention is as follows: in one aspect, the present invention provides an ultrashort pulse synchronous test device based on optical kerr effect, which is characterized by comprising: The external injection signal light is picosecond pulse light or femtosecond pulse light as reference light; The polarizer is used for adjusting the polarization direction of the externally injected signal light; the delay line is used for generating space delay, adjusting the time delay of the externally injected signal light and making the externally injected signal light incident to the optical Kerr medium; The optical Kerr medium is used for generating optical Kerr effect when 2 or more synchronous pulses are incident to the optical Kerr medium, so that the polarization state of the externally injected signal light is changed; An analyzer, the optical axis direction of which is perpendicular to the optical axis direction of the polarizer, for detecting the optical kerr effect; the detector is used for detecting the pulse intensity and the phase distribution after being transmitted or reflected by the analyzer; The control and data processing module is used for controlling the detector and all delay lines, processing the acquired data, acquiring delay information between different pulses to be synchronized and external injection signal light, and synchronizing with a plurality of pulses to be synchronized of the pulses to be synchronized; The first beam of pulse to be synchronized and the N beam of pulse to be synchronized are N beams of pulse to be synchronized, which are picosecond or femtosecond pulse light, wherein N is more than or equal to 2, and the included angle between the N beams o