Resonant sidebands in soliton fiber lasers have garnered substantial interest in recent years due to their crucial role in understanding soliton propagation and interaction dynamics. However, most previous studies and applications were restricted to focusing on only the first few low-order resonant sidebands because higher-order sidebands usually decay exponentially as their wavelengths shift far away from the soliton center and are negligibly weak. Here we report numerically and experimentally significant enhancement of multiple resonant sidebands in a soliton fiber laser mode-locked by a nonlinear polarization evolution mechanism. The birefringence and the gain profile of the laser cavity were shown to be critical for this phenomenon. Multiple intense resonant sidebands were generated whose maximum intensity was more than 30 dB higher than that of the soliton, which is the highest yet reported, to our knowledge. To accurately predict the wavelengths of all high-order resonant sidebands, an explicit formula was derived by taking the third-order dispersion effect into account. The temporal features of multiple orders of resonant sidebands were characterized, which all exhibit exponentially decaying leading edges. This study provides insight into understanding the properties of high-order resonant sidebands in a soliton laser and opens possibilities for constructing multi-wavelength laser sources.

为了改善传统随机并行梯度下降(Stochastic Parallel Gradient Descent, SPGD)算法收敛速度慢且容易陷入局部极值的问题，提出了一种元启发式随机并行梯度下降(Meta-Heuristic SPGD, MHSPGD)算法。该算法将SPGD算法和元启发式算法的开发与探索两步结合，首先利用SPGD算法的梯度下降搜索得到局部最优解，然后进行邻域搜索得到局部最优区域以外的可能最优解，通过所有解性能指标的比较来确定新的迭代起点。随着搜索范围的自适应扩展，该算法能够避免陷入局部极值并趋向收敛于全局最优。同时，为了避免重复搜索，建立了记忆表来记录迭代过程中产生的次最优解。搭建了无波前探测器自适应光学系统模型，运用所提算法对不同湍流强度下的波前畸变进行了仿真校正，并针对不同Zernike阶数的像差进行了仿真实验。在三种湍流强度下，MHSPGD算法所能达到的斯特列尔比(Strehl Ratio, SR)分别为0.7621、0.6554、0.3749，相比于SPGD算法分别提升了0.1%、2%和18.6%。此外，当畸变中含有较多高阶成分时，文中所提优化算法相比传统的SPGD算法，SR收敛到0.6所需的迭代次数减少了约47%，且SR收敛极限值也提升了约9.4%。结果表明：与三种主流优化算法相比，MHSPGD在保持较快收敛速度的同时，能够在各种湍流强度下达到更高的收敛极限，有效地解决了算法的局部收敛问题。

This study proposes a novel interferometric fiber optic gyroscope (IFOG) based on an integrated optical chip, application-specific integrated circuit, and small-diameter sensing coil. The overall size and weight of the prototype are 30mm×30mm×30mm and 68 g, respectively, making it the smallest closed-loop IFOG, to the best of our knowledge. A static experiment shows that the bias stability of the integrated IFOG is very close to the theoretical accuracy limit determined by the fiber coil and can satisfy the requirements of near-navigation-grade compact inertial navigation systems.

We demonstrated the efficient plasmon-induced nonlinear absorption of liquid metal GaInSn nanospheres prepared by a facile liquid-phase method. With GaInSn as saturable absorbers, a passively Q-switching operation was obtained at both 1.3 and 2 μm. The pulse width of 32 ns was achieved at 1.3 μm with repetition rate of 44 kHz, single pulse energy of 51.9 μJ, and output power of 425 mW. Meanwhile, 510 ns and 92 kHz pulses with energy of 36.1 μJ and output power of 2.48 W were obtained at 2 μm. This work provides the potential of liquid metal for improving metal functions and flexible optical devices.

Alloying in two-dimension has been a hot spot in the development of new, versatile systems of optics and electronics. Alloys have been demonstrated to be a fascinating strategy to modulate the chemical and electronic properties of two-dimensional nanosheets. We firstly reported ultra-broadband enhanced nonlinear saturable absorption of Mo_0.53W_0.47Te₂ alloy at 0.6, 1.0, and 2.0 μm. The nonlinear saturable absorption of Mo_0.53W_0.47Te₂ saturable absorber (SA) was measured by the open aperture Z-scan technique. Compared to MoTe₂ and WTe₂ SAs, the Mo_0.53W_0.47Te₂ SA showed five times deeper modulation depth, 8.6% lower saturable intensity, and one order larger figure of merit. Thus, our research provides a method of alloys to find novel materials with more outstanding properties for optics and optoelectronic applications.

Due to the composition-dependent properties of two-dimensional (2D) transition metal dichalcogenides (TMDs), alloying of existing dissimilar TMDs architecture is a novel and controllable route to tailor crystal structures with superior optical and optoelectronic properties. Here, we reported the hexagonal-phase WSe_1.4Te_0.6 alloy can enable great promise for enhanced saturable absorption response exceeding the parent component WSe₂ and WTe₂, with larger modulation depth and lower saturable intensity. These advantages allowed the 1064 nm passively Q-switched lasers based on WSe_1.4Te_0.6 to be more efficient, with pulse duration narrowed to 45%, and slope efficiency increased by 232%. Our findings highlighted the appropriate alloying of TMDs as an effective strategy for development of saturable absorbers.