Despite considerable progress in multi-stage laser wakefield acceleration (MSLWFA), efficient coupling between stages and the impact of laser-beam injection delay remains open challenges. A two-stage LWFA scheme is demonstrated using particle-in-cell (PIC) simulations, capable of producing multi-GeV electron beams over millimeter-scale propagation lengths. In the first stage, a high-intensity laser pulse (with [Formula: see text] [Formula: see text], [Formula: see text]= 800 [Formula: see text] and [Formula: see text]) propagates through a neutral helium (He) gas target inside a gas cell, with ionization modeled self-consistently to produce a fully ionized plasma at a plateau density [Formula: see text], generating a high-quality 1 GeV electron beam. This beam is then injected into a second stage inside the same gas cell, where systematically varying the injection delay enhances the injected bunch energy to 2.5 GeV and boosts background trapped electrons to 3 GeV, while reducing energy spread and preserving charge. These findings underscore the critical role of synchronization and plasma tailoring strategies relevant for future multi-pulse and flying-focus LWFA configurations.

Blazed gratings play a vital role in wavelength dispersion and directional beam steering, and the emergence of metasurfaces has opened new opportunities for compact and flexible blazed diffraction devices.However, whether in conventional or metasurface-based implementations, achieving stable and mutually independent wavefront responses under multi-wavelength operation remains a significant challenge.This work presents a metagrating design strategy that enables independent control of blazed diffraction across multiple wavelength bands, providing broadband wavefront manipulation within a single device. By arranging different circularly symmetric nanopillar units in an interleaved manner within a single planar layer and tuning the phase coverage for each wavelength band, multiple blazed diffraction modes can be achieved within a single device, with phase responses remaining independent across different bands. Such all-dielectric metagratings exhibit blazed diffraction behavior consistent with the design across both the visible and near-infrared bands, such all-dielectric metagratings exhibit blazed diffraction behavior consistent with the design across both the visible and near-infrared bands, with more than 90% of the transmitted energy concentrated in the designed diffraction orders. This work provides a compact and scalable design framework for multi-wavelength diffractive optical devices, with potential applications in planar optical systems.

The suppression of ablative Rayleigh-Taylor instability (ARTI) by a spatially modulated laser in inertial confinement fusion (ICF) is studied through numerical simulations. The results show that in the acceleration phase of ICF implosion, the growth of ARTI can be suppressed by using a short-wavelength spatially modulated laser. The ARTI growth rate decreases as the wavelength of the spatially modulated laser decreases, and ARTI is completely suppressed after a certain wavelength has been reached. A spatially uniform laser is introduced to keep the state of motion of the implosion fluid consistent, and it is found that the proportion of the spatially modulated laser required for complete suppression of ARTI decreases as the wavelength continues to decrease. We also optimize the spatial intensity distribution of the spatially modulated laser. In addition, as the duration of the spatially modulated laser decreases, the proportion required for completely suppressing ARTI increases, but the required energy decreases. When the perturbation wavenumber decreases, the wavelength of the spatially modulated laser required for complete suppression of ARTI becomes longer. In the case of multimode perturbation, ARTI can also be significantly suppressed by a spatially modulated laser, and the perturbation amplitude can be reduced to less than 10% of that without a spatially modulated laser. We believe that the conclusions drawn from our simulations can provide the basis for new approaches to control ARTI in ICF.

This work conducts a comparative study of the different mechanisms involved in supercontinuum generation in photonic crystal fibers (PCFs) when pumped within the normal and anomalous dispersion regimes. A femtosecond laser operating at 1030 nm was employed to pump both a commercial PCF with a zero-dispersion wavelength (ZDW) of 1210 nm and a custom-fabricated PCF exhibiting a ZDW of 916 nm. The findings indicate that pumping in the anomalous dispersion region elicits pronounced nonlinear effects. Using the custom-designed PCF, an ultra-broadband spectrum spanning 350-2100 nm was achieved, demonstrating spectral broadening markedly superior to that observed in the commercial PCF pumped in the normal dispersion region. This work not only realized a supercontinuum extending nearly three octaves from the ultraviolet to the mid-infrared through tailored design of the PCF's air-hole array structure but also revealed the critical role of the pump dispersion region in nonlinear processes and spectral broadening, providing important references for customizing high-performance supercontinuum sources.

Coherent combining of several low-energy few-cycle beams offers a reliable and feasible approach to producing few-cycle laser pulses with energies exceeding the multi-joule level.However,time synchronization and carrier-envelope phase difference(ΔCEP)between pulses significantly affect the temporal waveform and intensity of the combined pulse,requiring precise measurement and control.Here,we propose a concise optical method based on the phase retrieval of spectral interference and quadratic function symmetry axis fitting to simultaneously measure the time synchronization and ΔCEP between few-cycle pulses.The control precision of our coherent beam combining system can achieve a time delay stability within 42 as and ΔCEP measurement precision of 40 mrad,enabling a maximum combining efficiency of 98.5％.This method can effectively improve the performance and stability of coherent beam combining systems for few-cycle lasers,which will facilitate the obtaining of high-quality few-cycle lasers with high energy.

Laser-driven inertial confinement fusion (ICF) diagnostics play a crucial role in understanding the complex physical processes governing ICF and enabling ignition. During the ICF process, the interaction between the high-power laser and ablation material leads to the formation of a plasma critical surface, which reflects a significant portion of the driving laser, reducing the efficiency of laser energy conversion into implosive kinetic energy. Effective diagnostic methods for the critical surface remain elusive. In this work, we propose a novel optical diagnostic approach to investigate the plasma critical surface. This method has been experimentally validated, providing new insights into the critical surface morphology and dynamics. This advancement represents a significant step forward in ICF diagnostic capabilities,with the potential to inform strategies for enhancing the uniformity of the driving laser and target surface, ultimately improving the efficiency of converting laser energy into implosion kinetic energy and enabling ignition.

Objective Chirp rate measurement is essential for pulse compression with chirped pulse amplification (CPA) and for chirped pulse utilization in physical experiments. Methods such as frequency-resolved optical gating (FROG), cross correlation frequency resolved optical gating (X-FROG), time-domain ptychography (TDP), two-dimensional spectral shearing interferometry (2DSI), and spectral phase interferometry for direct electric field reconstruction (SPIDER) are widely adopted for measuring pulses with sub-picosecond durations. Moreover, although a two-dimensional extension of the stationary phase point (SPP) method can be applied to the dispersion measurement of long pulses with durations exceeding tens of picoseconds, it achieves this by analyzing the phase behavior near the SPP in the interference fringes. In this paper, we propose a concept for chirp rate measurement based on a temporal-spectral scanning parametric process (TSSP). Methods The chirped pulse to be measured is beam split, with one branch providing the narrow bandwidth probe beam and the other maintaining a high fidelity with incidence. They are injected into a nonlinear crystal to realize noncollinear sum-frequency generation (NSFG). By precisely introducing a temporal delay into the probe beam, a temporal-spectral scanning between the probe beam and chirped pulse is achieved. Simultaneously, the sum-frequency generation (SFG) at different temporal delays is recorded. The chirped rate can be achieved by numerical calculation on the temporal delay and NSFG spectrum. The TSSP only requires recording the central wavelength of the SFG, rather than capturing intensity or interference fringes. Results and Discussions The time delay corresponding to different SFG spectra measured using the TSSP is shown as the dashed curve in Fig. 5(a). Correspondingly, the theoretical time delay calculated based on Eq. (5) with a preset grating separation of b(0)=34.3 mm is depicted as the solid curve in Fig. 5(a). A comparison of these two curves reveals that the deviation between the experimental measurements and theoretical calculations is minimal. When selecting a probe wavelength of 807.73 nm, the spectral component of the SFG signal is in one-to-one correspondence with the spectral component of the injected chirped pulse. Within a spectral width of 51.42 nm, ranging from 777 nm to 829 nm, the experimentally measured time delay is 20.63 ps, which results in a difference of 0.43 ps and a total deviation rate of 2.04% compared with the theoretical value of 21.06 ps. This demonstrates that the TSSP method achieves high accuracy in chirp rate measurements for pulses with durations on the order of tens of picoseconds. In this experiment, the primary source of deviation is the limited optical resolution of the spectrometer. Employing a spectrometer with higher optical resolution can effectively enhance the accuracy of chirp rate measurements. For instance, the spectrometer used in this study has an optical resolution of 0.5 nm, leading to a theoretical maximum measurement deviation of 2.99%. Commercially available spectrometers can achieve optical resolutions as high as 0.01 nm, theoretically reducing the deviation to 0.04%. Furthermore, if the TSSP method is applied to the measurement of chirped pulses with broader pulse durations, the measurement deviation will further decrease. In the field of picosecond pulse width measurements, the TSSP method exhibits significantly higher measurement accuracy than that based on the autocorrelation principle of large-aperture nonlinear crystals, highlighting its substantial application potential in picosecond pulse characterization. Figure 5(b) presents a comparison between the chirp rate measured using the TSSP method and the preset chirp rate. The solid curve represents the experimental measurements, calculated by substituting the SFG wavelength data and corresponding time delays obtained by the TSSP method into Eq. (4). The dashed curve is a fitted curve based on the experimental data, whereas the dotted curve represents the theoretical chirp rate derived from Eq. (6) using the preset grating separation. The fluctuations observed in the solid curve mainly originate from the derivative operation on the SFG wavelength in Eq. (4), which makes it highly sensitive to the recorded central wavelength data in the experiment. If a spectrometer with extremely high optical resolution is used for SFG spectrum measurements, ensuring more accurate recording of the central wavelength data, these fluctuations will be significantly reduced. The deviation between the theoretically preset chirp rate and the experimentally fitted chirp rate is nearly zero around 812 nm, with maximum deviations of approximately 5.9% and 4.0% in the shorter and longer wavelength regions, respectively, both significantly smaller than the fluctuations observed in the solid curve. This is because the SFG signal is independently measured and recorded during scanning, ensuring non-divergence of the measurement data in the TSSP method. Consequently, the fitted curve closely matches the theoretical curve, further validating the accuracy and reliability of the TSSP method. Conclusions This paper proposes an absolute chirp rate measurement method based on a time-frequency scanning nonlinear process. A TSSP-based measurement is implemented and experimentally studied using the front end of the SG-II 5 PW laser system. For a spectral range of 777?829 nm (pulse width Delta lambda=51.42 nm), the experimentally measured relative time delay is 20.63 ps, which compared with the preset value of 21.06 ps, yields a relative deviation of 2.04%. Furthermore, the chirp rate obtained from fitting the experimental data shows minimal deviation from the theoretical preset value near the central wavelength, demonstrating the high accuracy of TSSP measurements. The TSSP method is a simple and direct measurement technique that does not require algorithmic reconstruction, intensity distribution measurement, or interference fringe analysis. When combined with a high-optical-resolution spectrometer, it not only achieves higher measurement accuracy but is also applicable to chirp rate measurements for pulses with durations ranging from tens of picoseconds to nanoseconds. Additionally, by incorporating intensity information and phase reconstruction algorithms, the TSSP method holds significant potential for applications in the spectral phase and pulse width measurements.

The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability (ARTI) in inertial confinement fusion (ICF) is studied with two-dimensional numerical simulations. The results show that in the plasma acceleration phase, shorter wavelengths lead to more efficient coupling between the laser and the kinetic energy of the implosion fluid. Under the condition that the laser energy coupled to the implosion fluid is constant, the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band, reaching its minimum value near λ = 65 nm, and when the laser wavelength continuously moves toward the X-ray band, the ARTI growth rate increases rapidly. It is found that the results deviate from the theoretical ARTI growth rate. As the laser intensity benchmark increases, the position of the minimum ARTI growth rate shifts toward shorter wavelengths. As the initial sinusoidal perturbation wavenumber decreases, the position of the minimum ARTI growth rate shifts toward longer wavelengths. We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.

Pulsed solid-state lasers comprise 2D materials as saturable absorbers that contain transparent windows of the atmosphere and characteristic fingerprint spectra of several vital molecules that are significant in various applications and research. Over the past few decades, significant progress has been made in the development of narrow pulse width, high energy, high average output power, high efficiency, and simple construction of passively Q-switched and mode-locked lasers with 2D materials as saturable absorbers. This review summarizes the development of 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, topological insulators, and MXenes, as modulator devices for solid-state lasers owing to their broadband operation, excellent nonlinear optical response, low recovery time, ultrafast dynamic processing, and easy fabrication. Then, some new emerging and representative applications of pulsed solid-state lasers are introduced and illustrated such as laser surgery, material processing, and lidar. Finally, future challenges and perspectives of pulsed solid-state lasers with 2D materials-based saturable absorbers are analyzed and addressed. The rapid development of pulsed solid-state lasers with the continuous improvement of modulation technology is expected to expand opportunities for application in industry, scientific, medical, and other areas. Currently, important progress is achieved in the development of narrow pulse width, high average output power, repetition rate, and simple construction of pulsed solid-state laser based on 2D material saturable absorptions. This review summarizes the properties and applications of the pulsed solid-state lasers based on 2D material saturable absorptions, as well as future challenges and directions. image

In this paper, TaSe2 material was prepared and used as a saturable absorber (SA) to modulate a Tm:YAP laser. Under the continuous-wave mode, an 18.31 W diode laser was used to pump the Tm:YAP crystal, and an output power of 6.22 W was achieved at 1993.1 nm with an optical-optical conversion efficiency of 33.9%. Under the passively Q-switched mode, the Tm:YAP pulse laser was modulated by a TaSe2-based SA, and a 2.8 W average power and a 440 ns pulse width at 73.15 kHz were obtained at 1988.4 nm, corresponding to an optical-optical conversion efficiency of 15.2% and a per pulse energy of 38.2 mu J.

Optical parametric amplification (OPA) is a promising method of producing extremely intense light. A new OPA scheme with comprehensively high performance is urgently required for future development. In this study, an amplification scheme known as crossed-Fabry-Perot-cavity OPA (XOPA) is proposed. It is based on the principle of periodic idler elimination, which prevents energy back-conversion among the three coupling waves, resulting in a monotonically increasing overall conversion efficiency. Using a signal at 808 nm and a pump at 532 nm, a chirped pulse XOPA is experimentally demonstrated with a conversion efficiency of 56.28% and a gain bandwidth of 120 nm. The measured pulse duration after compression is 19.2 fs, which is comparable to the Fourier-transform-limited 16.8 fs. Further investigations revealed several advantages. Stable pulse shaping in spatial, temporal, and frequency domains is realized by a spatiotemporally modulated pump. Pulse contrast adjustability on the front edge of the signal is verified in the XOPA of different Fabry-Perot cavity lengths. These results indicate astringency and precise regulation of output in nonlinear processes. Considering numerous crystals suitable for noncollinear configurations from the near-infrared to mid-infrared regions, XOPA has a universal potential application in laser systems with extreme intensity, few-cycle duration, and internal confinement fusion drivers. A Crossed-Fabry-Perot-Cavity OPA (XOPA) scheme is proposed and experimentally demonstrated. The pump-to-signal conversion efficiency of up to 56.28% and gain bandwidth of 120 nm are simultaneously achieved with signal pulses at 808 nm and pump 532 nm. The excellent performance makes XOPA universal potential utilization in laser systems of extreme intensity, few-cycle duration, and internal confinement fusion drivers. image

在激光领域,不断地探寻高功率高亮度的激光源是该领域科研工作者一直坚持的方向,而且在各大领域也有着重要应用.然而,单一激光器输出功率的提高有着很大的难度,而另一种获得高光束质量激光源的方式成为目前主要的研究方向——多光束合成技术.本文调研了近年来利用多光束合成技术产生高功率激光方面的研究进展,特别对相干光束合成和光谱合束两种技术路线做了详细的介绍.最后展望了未来激光合成技术的发展方向.

As optical parametric chirped pulse amplification has been widely adopted for the generation of extreme intensity laser sources, nonlinear crystals of large aperture are demanded for high-energy amplifiers. Yttrium calcium oxyborate (YCa4O(BO3)(3), YCOB) is capable of being grown with apertures exceeding 100 mm, which makes it possible for application in systems of petawatt scale. In this paper, we experimentally demonstrated for the first time to our knowledge, an ultra-broadband non-collinear optical parametric amplifier with YCOB for petawatt-scale compressed pulse generation at 800 nm. Based on the SG-II 5 PW facility, amplified signal energy of approximately 40 J was achieved and pump-to-signal conversion efficiency was up to 42.3%. A gain bandwidth of 87 nm was realized and supported a compressed pulse duration of 22.3 fs. The near-field and wavefront aberration represented excellent characteristics, which were comparable with those achieved in lithium triborate-based amplifiers. These results verified the great potential for YCOB utilization in the future.

We present a new scheme of picosecond optical parametric chirped pulse amplification (OPCPA) in which a Fourier-transform-limit 5.0 ps pulse is optically sheared from a single-longitudinal-mode 1064 nm CW laser. The pulse is amplified and frequency-doubled as the pump in order to maintain the pump narrow bandwidth and picosecond duration simultaneously, which is very important to ensure the high temporal contrast for an OPCPA amplifier. Combined with the cross-polarized wave generation (XPW), a compound frontend for the high-power femtosecond laser system that delivers a 1 Hz chirped pulse train is established. The experiments provide an output pulse energy of 17.1 mJ, a spectrum bandwidth 71 nm (FWHM), and a pulse duration 16.4 fs. The pulse contrast reaches 1:10−12 several picoseconds before the peak of the main pulse, which is the best value of the available measuring instruments.

We focused on a single-shot method for directly measuring the temporal contrast enhancement of a single plasma mirror by analyzing the spectrum of a chirped pulse spatiotemporally overlapped with the igniting laser used for generating a plasma mirror. Experimentally, temporal contrast enhancement of 10(2) by one plasma mirror was successfully measured in a hundred picosecond timescale and was consistent with the theory. This single-shot measurement method caused no degradation on the performance of the plasma mirror, which was proved by monitoring the efficiency and far-field pattern of the igniting laser after the plasma mirror. Combined with calorimeters and CCD cameras, this method is expected to realize the single-shot online diagnosis of plasma mirrors. This method is expected to be an efficient approach for measuring the temporal contrast enhancement of the plasma mirrors.

We proposed a self-referenced technique for measuring the spatiotemporal characteristics of ultrashort pulses using the coherent diffraction imaging. This technique includes the wavelength spatial multiplexing coherent diffraction imaging measurement and the three-dimensional spatiotemporal amplitude and phase reconstruction. In experiment, we verified the feasibility of this technique by measuring a pulse from the femtosecond laser oscillator. Wavelength spatial multiplexing was realized by the combination of two-dimensional diffracted optical element and narrow-band-pass filter, and the amplitude and phase information of each wavelength was recovered by ePIE (extended Ptychographic Iterative Engine) algorithm. This technique can measure the three-dimensional spatiotemporal amplitude and phase information of ultrashort pulses with high resolution and simplicity. In the future, it is expected to be an effective method for the comprehensive monitoring of the spatiotemporal optical field of ultrashort pulse lasers, and will be helpful for the laser performance improvement.

高精度转台在诸多领域有着广泛的应用,为了提高其转台角分度精度,提出了一种高精度角分度转台及其误差修正方法.首先,介绍了转台的结构设计,转台采用了蜗轮蜗杆传动、圆光栅测角的形式,轴承采用了交叉滚柱轴环,圆光栅采用了增量式,对转台的载物台面进行了力学仿真分析,考察了转台的静力学性能及模态特征;然后,利用多齿分度台和自准直仪对转台的测角精度进行了标定,根据标定获得的误差分布规律,采用基于查表的方法进行了误差补偿,对于整度数之间无标定数据的部分,采用线性插值的方法获得了误差修正量,从而建立了完整的0～360°范围内的误差修正量数表;最后,分别利用多齿分度台和十七面体对误差修正效果进行了实验验证.研究结果表明:利用该方法进行误差补偿,测角最大误差由32.12″降低到1.95″;同时,查表法有效修正了测角误差,使转台可以满足实际场合的使用要求.

高次谐波产生(High-order Harmonic Generation,HHG)使激光脉冲脉宽突破到阿秒量级成为可能.2001年第一次在实验上利用高次谐波产生的方法获得了650 as的脉冲,揭开了阿秒时代的序幕.根据介质的不同大致可以分为气体高次谐波、固体体材料高次谐波和固体等离子体高次谐波.气体高次谐波经过了二十多年已经发展得很成熟,并能通过气体高次谐波获得最短43 as的脉冲.固体体材料高次谐波和固体等离子体高次谐波因为转化效率高、光子能量高等独特优势已经成为产生阿秒脉冲的研究热点.本文主要介绍了高次谐波的发展历史,气体高次谐波、固体体材料高次谐波和固体等离子体高次谐波的发展现状以及阿秒脉冲测量和表征技术的发展,并对未来的发展趋势进行了总结展望.

Objective In the past 20 years, ultra-short ultra-intense laser technology has experienced rapid development. However, the maximum output power of these lasers is limited by nonlinear effects, large diameter compression grating technology, gain bandwidth limitations, and other factors. One of the most promising technologies to further enhance output ability is coherent beam combining. Effective coherent beam combining requires strict inter-beam synchronization. In recent years, many attempts have been made to improve synchronous measurement and control. The research progress of most implementations has been solely based on photoelectric detection, optical balanced cross-correlation, and temporal and spatial interferences. Nevertheless, these methods need to maintain the time interval of the two beams in coherent time, limiting the femtosecond pulse synchronous measurement range within 1 ps. The ability of an electronic oscilloscope to achieve a time resolution less than 10 ps is difficult; therefore, it is more difficult to accurately measure the pulse delay within 1-10 ps. In addition, for online synchronous measurement of a multichannel ultra-short pulse coherent beam combining system, the abovementioned methods are more complicated to implement and cannot achieve a single-shot measurement. In this paper, a single-shot measurement method for a multichannel ultra-short pulse with large dynamic range time synchronization based on all-fiber spectral interference is proposed. This method has a wider measurement range to measure synchronization than the nonlinear correlation method and a larger measurement accuracy than an oscilloscope. Our method improves efficiency in multichannel laser synchronous measurements for engineering applications and has important application potential for multichannel ultra-short pulse laser coherent beam combining systems. Methods First, theoretical and simulation analyses based on multichannel optical fiber array spectral interferometry were carried out. Predictions of tau and tau(max) for the designated measurement range were made according to Equation (6). Considering the purpose of synchronous measurements, this study created the concept of fixed time offset. The beneficial effect of this concept is that through the comparison of measured values and fixed offset time, we can determine the absolute time difference between the referenced light and the light to be measured. Moreover, with a fixed offset time, when the measured values were equal to the fixed offset times introduced by optical delay lines on the referenced light fiber paths, the two pulses reached a zero-synchronization state. In our experiment, the feasibility of the single-shot multichannel synchronous measurement method was verified. The experimental optical path was built using the path of a four-channel pulse synchronous measurement as an example (Fig. 3). The three formed interference signals and one beam of reference light were input to the imaging spectrometer using a multipath fiber buncher. Results and Discussions The spectrogram in the experiments is recorded by an imaging spectrometer, which indicates that the spectrometer has the ability to record 20 signals (Fig. 4). The delay, r, between the reference and measured beams is obtained through the data processing method described in Section 2. 1. This method illustrates that rmax is equal to 14. 751 ps and r is equal to 1.055 ps, which determine the measurable range (Fig. 5). From experimental results, the range that can be measured is slightly less than the theoretical interval, mainly due to airflow disturbances, mechanical vibration, and dark current noise from the spectrometer. For measurement precision of different offset points, the deviation of the statistical mean value of multiple measurement results is obtained from the present value. In Figure 6, it is shown that with the increase of temporal spacing (TS) between the two pulses, the beta value decreases. When TS reaches 6.139 ps, the beta value is at its minimum. When TS is greater than 6.139 ps, the p value increases continuously. The measured jitter, gamma, is shown on the right vertical coordinate of Figure 6 and it shows the same trend as the beta value (Fig. 6). Measurement error is because of uncertainty of the wavelength or frequency spacing of the interference fringe in the spectrogram caused by noise. However, the degree of response of different fixed offset times to noise is different. Therefore, the measurement accuracy is varied at different fixed offset times. Conclusions This paper demonstrates that the single-shot synchronous measurement technique for a multichannel ultra -short pulse laser based on all-fiber spectral interference is feasible through simulation and experiment. The measuring range is determined by the spectral interference fringe spacing, and the theoretical simulation results show that a fixed time offset is beneficial for the realization of a zero-synchronization state measurement. The optimal solution of the offset time is obtained using experimental statistical results. Experimental data prove that setting the fixed time offset in the center of the measurable range area can improve measurement accuracy. The minimum time synchronization accuracy is 5.3 fs and the measurement range is 1.055-14.751 ps, which are in good agreement with results of the theoretical analysis. The all-fiber spectral interference synchronization measurement method combines the characteristics of spectral interference and optical fiber array in design. The advantages of the method are easy integration of an optical fiber path, fast processing speed of spectral interference data, and lowenergy demand of signals. Our method can satisfy the ultra-short ultra-intense laser facility real-time and multichannel measurement diagnosis requirements. The method also makes up for a small measurement range and poor temporal resolution when measuring the synchronization state using the nonlinear correlation method and an oscilloscope, respectively. The complexity of the configuration and difficulty of a single-shot measurement in multichannel synchronous measurements are solved. Therefore, our method has important application prospects in multichannel ultra-short pulse laser coherent beam combining systems.

基于迈克尔逊干涉原理,利用干涉成像原理和图像处理技术,提出了利用干涉条纹半径变化情况来获取干涉条纹位移信息的方法.该方法以面阵CCD相机采集的图像为处理对象,采用去噪、顶帽变换、二值化、形态学处理等预处理操作,再利用连通域特征识别得到图像中心亮干涉条纹的半径.通过半径的变化趋势与幅度,实现位移信息提取.实验表明,所提方法突破了干涉条纹计数时位移检测最高分辨率为λ/2的限制,利用了每帧干涉图像所提供的变化信息,实现位移检测分辨率λ/4.