采用光强度调制鉴相方案,使用直接数字频率合成器(DDS)和激光驱动器产生频率稳定的调制激光,注入待测光路,在待测光路后进行光电转换和放大,引入参考本振信号作为混频器相位参考信号,利用混频器测量待测光路信号与参考本振信号的相位差,获得光路延时信息。主要特点如下:提出了在本振信号链路三段移相的差分式检测方法,优化了鉴相点,提高了测量精度;采用单段短时两相位点测量模式,有效降低了光源功率波动、光路中光强波动、光电探测及放大电路增益波动、温度变化导致相位差漂移等带来的测量误差;在每个相位点多次测量采样,根据测量的平均值计算相位差,推导时间差。详细分析了测量电压和被测时延之间的函数关系,分析了影响测量精度的因素,构建验证系统,完成了实验验证。实验结果表明:本方案在4 ns的时延内的测量精度可达1 ps,大幅提升了现有高功率激光装置的同步测量精度。

提出应用于激光脉冲高精度时间同步测量的技术方案。利用时间数字转换技术, 精确测量激光脉冲相对延时, 测量精度可小于10 ps(峰谷值)。为满足测量电路对脉冲宽度的要求, 设计针对短脉冲激光的电脉冲展宽模块, 可以将百皮秒量级的电脉冲展宽至纳秒量级, 引入时间抖动的均方根值小于2 ps。该测量方案实现了实时高精度时间同步测量, 可以作为时间同步反馈补偿的实时监测使用。

针对布里渊光时域反射型 (BOTDR)分布式光纤传感系统中脉冲光源消光比易受偏置电压漂移影响的问题，本文提出了一种结合双电极串联结构电光调制器(EOM)及“扫描.步进跟踪”算法的脉冲光源消光比自动控制方法。实验结果表明，该方法可将 EOM输出脉冲光的消光比稳定在 50 dB以上。在 150 min的测试时间里，输出脉冲光消光比的最大值为 52.4 dB，最小值为 51.1 dB，波动值仅为 1.3 dB。该方法对 BOTDR光纤传感系统及高功率激光驱动装置等设备中脉冲光源性能的提升具有重要意义。

提出应用于神光Ⅱ装置中的拍瓦短脉冲与主压缩脉冲高精度同步方案。在该方案中，通过与门技术实现了锁模激光器输出的短脉冲序列与主激光总控触发信号时间的初步锁定，该技术是实现惯性约束核聚变高功率激光装置中长短脉冲精确同步的关键。由总控系统的触发信号作为与门中可编程现场门阵列(FPGA)电路的触发信号，锁模激光器输出的百皮秒激光脉冲通过光电转换放大,并由同步展宽装置进行处理之后，作为FPGA电路的时钟信号，能够实现系统主激光门脉冲触发信号与短脉冲激光之间均方根值为26.3 ps的同步精度，这一技术可有效提升装置中同步系统的稳定性。

对掺铁铌酸锂晶体在高功率超短脉冲激光照射下的光折变指数进行半定量的理论计算并实验验证。由理论计算得出在高功率超短脉冲激光(0.33 mJ,10 ps，527 nm)作用下，掺铁铌酸锂晶体的折射率指数变化量达到10-4量级，在几个纳秒的弛豫时间后降低到10-5量级。实验采用同样的超短脉冲平顶激光，经过空间整形，形成空间强度分布为直角三角形的激光光束，照射掺铁铌酸锂晶体发生光折变，产生直角棱镜，使得经过瞬时光折变棱镜的1053 nm脉冲信号光发生偏转，根据偏转的角度计算出的折射率指数减小量为10-5量级，理论计算与实验结果较为相符。这项研究表明利用掺铁铌酸锂晶体的瞬时光折变效应将有望实现全光条纹相机对短脉冲时间特性的测量。

提出了一种提高纳秒光脉冲单次测量动态范围的方法，其中光纤脉冲复制环用来产生时域上幅度呈指数递减的脉冲复制串，有效环增益为0.955。经软件补偿脉冲复制串使其具有相同的幅度，然后累加平均前18个脉冲，能够将注入的单发纳秒光脉冲动态范围提高2.74倍，这样就可以实现利用光电探测管和示波器对1001高对比度的惯性约束核聚变(ICF)脉冲测量。

为了减小高功率激光装置中高压干扰电信号对触发脉冲信号的影响，提出了一种可抗干扰、低时间抖动、快上升沿、高精度的光电触发模块。它由发射模块和接收模块构成，发射模块和接收模块之间通过光纤连接。由于触发信号以光信号的方式传送到终端，因此传输过程中触发信号不会受到电干扰信号的影响。该触发模块输出脉冲的上升沿为4.8 ns，对触发信号引入的时间抖动峰峰值约为317 ps，可以为输入阻抗为高阻或50 Ω匹配的被触发仪器提供4 V左右的逻辑门电路（TTL）输出电压，满足高功率激光装置的要求。

The technique of Brillouin scattering distributed optical fiber sensing has been presented. Optical heterodyne detection was used to detect the weak Brillouin back scattering signal based on single longitudinal mode distributed feedback (DFB) laser and electric optical modulation technique. The scattering signal was amplified effectively by improving the filter and erbium doped fiber amplifier (EDFA). The 11 GHz radio-frequency (RF) signal of Brillouin back scattering is gathered and averaged. The experimental procedures and results are presented. The results show that the peak power of Brillouin back scattering at 11 GHz can reach 50 mV, and the intensity noise of light source induced the system's signal to noise ratio (SNR) decreased greatly, which reduced the difficulty of signal process in demodulation system. The experimental results confirm that the configuration is feasible.

A diode-pumped Yb-doped double-clad fiber amplifier (YDDCFA) with the narrow bandwidth continuous wave (CW) and pulse input signal is investigated. The input single-mode (SM) signal bandwidth is 10^(-4) nm from a distributed feedback (DFB) fiber laser. The saturated gain of the CW amplification is 11 dB at the forward pump. And besides CW signals, we also amplify pulses with duration of 150 ns and the 1-Hz repetition. The pulse is amplified to 2 W of peak power, 0.31 microjoule of energy, 23 dB of gain and less than 6% of stability at the forward pump power of 1.4 W. For higher power, reflections and backscattering can generate the self pulsation in the amplifier. The results are important for the development of the narrow-band double-clad fiber amplifier.

Yb-doped phase-shifted fiber Bragg grating (PS-FBG) has been fabricated with phase shift introduced by shielded method. In the fabrication process, the PS-FBG is used as the laser cavity. Whether the introduced phase-shift is π/2 or not is determined by the laser output power. As long as the output power of the laser begins to drop down, the exposure is stopped, and the phase shift is π/2 then. It is necessary to anneal the PS-FBG to stabilize its characteristics, which will reduce the introduced phase-shift. The second exposure of the PS-FBG is needed to restore the π/2 phase shift. A fiber grating laser has been made with the method. When the pump power is 100 mW, the laser output is 25 mW with signal-noise-ratio (SNR) of 60 dB. Within 1 h the output fluctuation of the laser is less than 1%. The laser is always under single-mode operation when the temperature of the fiber grating is tuned between 25 ℃ and 30 ℃.