A high-energy 100-Hz optical parametric oscillator (OPO) based on a confocal unstable resonator with a Gaussian reflectivity mirror was demonstrated. A KTA-based OPO with a good beam quality was obtained when the magnification factor was 1.5, corresponding to the maximum signal (1.53 µm) energy of 56 mJ and idler (3.47 µm) energy of 20 mJ, respectively. The beam quality factors (M²) were measured to be M²_x = 5.7, M²_y = 5.9 for signal and M²_x = 8.4, M²_y = 8.1 for idler accordingly. The experimental results indicated that the beam quality positively changed with the increase of magnification factors, accompanied by an acceptable loss of pulse energy.

Re:YAG-SiO₂多组分玻璃光纤是以Re:YAG作为纤芯材料，以石英管作为包层材料，采用熔芯法利用拉丝塔在高温下拉制的特种光纤，具有掺杂浓度高、增益大、机械强度高、易与石英光纤熔接等优点，适用于短腔单频光纤激光器。文中介绍了Re:YAG-SiO₂光纤的制备工艺，结合笔者课题组在该领域的研究工作，综述了近年来基于Re:YAG-SiO₂光纤的单频激光技术在1.0 μm，1.5 μm及2.0 μm波段的研究进展，并对Re:YAG-SiO₂光纤的制备及基于该类光纤单频激光器所存在的问题进行了归纳分析，对未来的发展进行了展望。

Beam quality improvements by a large margin for signal and idler beams of a high energy 100 Hz KTiOAsO4 (KTA) non-critical phase matching (NCPM) optical parametric oscillator (OPO) were demonstrated using an unstable resonator configuration instead of a plane-parallel one. Theoretically, influences of cavity lengths and transmission of an output coupler on the OPO conversion efficiency for both were numerically simulated. For OPO based on an unstable resonator with a Gaussian reflectivity mirror, the maximum pulse energies at the signal (1.53 µm) and idler (3.47 µm) were about 75 mJ and 26 mJ, respectively. The corresponding beam quality factors of the signal were M_x² = 9.8 and M_y² = 9.9, and M_x² = 11.2 and M_y² = 11.5 for the idler. As a comparison, 128 mJ of signal and 48 mJ of idler were obtained with the plane-parallel resonator, and the M² factors of the signal were M_x² = 39.8 and M_y² = 38.4, and M_x² = 32.1 and M_y² = 31.4 for the idler. Compared with a plane-parallel cavity, over eight times and three times brightness improvements were realized for the signal and idler light, respectively.

An actively mode-locked fiber laser with controllable pulse repetition rate and tunable pulse duration is presented, in which an optical delay line (ODL) is used to adjust the cavity length precisely for regulating the repetition rate, and a semiconductor optical amplifier (SOA) is introduced for enabling the pulse duration control. Experimentally, continuous tuning of the repetition rate from 2 GHz to 6 GHz is realized, which is limited by the availability of an even higher repetition rate radio-frequency (RF) source. Specifically, when the repetition rate is fixed at 2.5 GHz, the pulse duration can be tuned from 4 ps to 30 ps, which is, to the best of our knowledge, the widest tuning range of pulse duration ever achieved in a gigahertz (GHz) repetition rate actively mode-locked 1.5 µm fiber laser oscillator.

双马赫-曾德(M-Z)干涉仪系统因其光路简单、灵敏度高、频率响应宽等独特优势受到了广泛的关注及应用，但由于其非常容易受到外界环境噪声的影响，直接采取互相关计算方法获取扰动信号位置会导致较大的测量误差。本文提出了一种基于希尔伯特-黄变换(HHT)的数据信号处理方案用于实现高精度的分布式光纤振动定位检测。通过对接收到的两路光信号进行经验模态分解得到本征模函数，并对所有本征模函数进行希尔伯特变换叠加得到希尔伯特谱，从而可以清晰直观地提取到由振动信号引起的高相似度光信号信息，再通过互相关计算由振动信号引起的时间延迟，从而准确计算振动位置信息。相比于传统的直接互相关计算方法，本方法可以有效识别及提取双M-Z干涉仪系统中振动信号引起的特征信息，从而可以有效降低外界环境噪声对系统的影响，减小定位误差。本文对所提出的方法进行了相关理论分析，并搭建了双M-Z干涉仪系统进行相关实验验证。实验结果表明，与传统直接互相关方法相比，本方法可以有效减少互相关数据的计算量，同时该方法可以有效提高振动位置的定位精度，在2 km的传感光纤长度、10 MHz采样率下，定位精度可达10 m。本文提出的基于双马赫-曾德干涉仪系统的分布式光纤传感技术具有较高的实际应用价值。