Ultra-high spectral purity lasers are of considerable research interests in numerous fields such as coherent optical communication, microwave photonics, distributed optical fiber sensing, gravitational wave detection, optical clock, and so on. Herein, to deeply purify laser spectrum with compact size under normal condition, we propose a novel and practical idea to effectively suppress the spontaneous radiation of the laser cavity through weak external distributed perturbation. Subsequently, a laser configuration consisting of a main lasing cavity and an external distributed feedback cavity is proposed. The feedback signal with continuous spatio-temporal phase transition controlled by a distributed feedback structure is injected into the main cavity, which can deeply suppress the coupling rate from the spontaneous radiation to the stimulated emission and extremely purify the laser spectrum. Eventually, an ultra-narrow linewidth on-chip laser system with a side mode suppression ratio greater than 80 dB, an output linewidth of 10 Hz, and a relative intensity noise less than -150 dB/Hz is successfully obtained under normal conditions. The proposed concept in this work provides a new perspective for extreme regulation of laser parameters by using weak external distributed perturbation, which can be valid for various gain-type lasers with wide wavelength bands.

The statistical dynamics of partially incoherent ultrafast lasers are complex and chaotic, which is significant for fundamental research and practical applications. We experimentally and theoretically reveal the statistical dynamics of the spectral evolutions and correlations in an incoherent noise-like rectangle pulse laser (NLRPL). Based on statistical histogram analysis, the probability distribution asymmetry of the spectral intensity fluctuation is decayed with the wavelength far away from the spectral peak due to the detection noise. The full-spectral correlation values indicate that the spectral similarity between two round trips is exponentially weakened as the round-trip offset increases. By studying the correlation map of spectral components, we find that the area of the high-correlation region is relevant to the pump power, which is reduced by increasing the pump power. The mutual information of the spectra demonstrates that two spectral components with symmetry about the spectral peak have a statistical dependence. Experimental observations and statistical properties can coincide well with theoretical numerical simulations. We reveal the pump-dependent spectral correlation of the NLRPL and provide multiple statistical methods for the characterizations of chaotic dynamics in incoherent light sources.

在浅水测深技术中，星载激光测量系统可以覆盖一些机载/舰载系统难以到达的偏远水域，具有比被动光学影像水深测量精度更高、可全天时工作等独特的优势。以稀疏而少量的主动星载激光测量值为水深标定点，融合被动星载遥感影像，主被动融合的浅水测深是当前的趋势。本文首先介绍了星载单光子激光雷达的工作范围、物理参数和数据产品，概述了测量原理，综述了现有的星载单光子激光雷达测深的理论传输模型，对比了不同的点云数据去噪处理算法的优劣，归纳了星载融合测深反演技术在不同环境中的应用，总结了当前存在的问题，并对该技术未来的前景和发展方向进行了展望。

针对目前Fe²⁺: ZnSe激光器缺乏有效的高功率泵浦源这一关键瓶颈，提出了采用连续波HF化学激光器泵浦Fe²⁺: ZnSe来实现4 μm波段激光输出的技术路线，结合实验和理论手段考察了此技术路线的可行性。首次获得了由连续波HF化学激光泵浦的Fe²⁺: ZnSe激光器的W级激光输出，输出功率约为1.7 W，谱线峰值波长为4.18 μm，出光时间约2 s。

Low-power and low-variability artificial neuronal devices are highly desired for high-performance neuromorphic computing. In this paper, an oscillation neuron based on a low-variability Ag nanodots (NDs) threshold switching (TS) device with low operation voltage, large on/off ratio and high uniformity is presented. Measurement results indicate that this neuron demonstrates self-oscillation behavior under applied voltages as low as 1 V. The oscillation frequency increases with the applied voltage pulse amplitude and decreases with the load resistance. It can then be used to evaluate the resistive random-access memory (RRAM) synaptic weights accurately when the oscillation neuron is connected to the output of the RRAM crossbar array for neuromorphic computing. Meanwhile, simulation results show that a large RRAM crossbar array (> 128 × 128) can be supported by our oscillation neuron owing to the high on/off ratio (> 10⁸) of Ag NDs TS device. Moreover, the high uniformity of the Ag NDs TS device helps improve the distribution of the output frequency and suppress the degradation of neural network recognition accuracy (< 1%). Therefore, the developed oscillation neuron based on the Ag NDs TS device shows great potential for future neuromorphic computing applications.

Dissipative solitons emerge as stable pulse solutions of nonintegrable and nonconservative nonlinear physical systems, owing to a balance of nonlinearity, dispersion, and loss/gain. A considerable research effort has been dedicated to characterizing amplitude and phase evolutions in the spatiotemporal dynamics of dissipative solitons emerging from fiber lasers. Yet, the picture of the buildup process of dissipative solitons in fiber lasers is incomplete in the absence of corresponding information about the polarization evolution. Here, we characterize probabilistic polarization distributions in the buildup of dissipative solitons in a net-normal dispersion fiber laser system, mode-locked by single-wall carbon nanotubes. The output optical spectra under different pump powers are filtered by a tunable filter, and are detected by a polarization state analyzer. The laser system operates from random amplified spontaneous emission into a stable dissipative soliton state as the cavity gain is progressively increased. Correspondingly, the state of polarization of each spectral wavelength converges towards a fixed point. To reveal the invariant polarization relationship among the various wavelength components of the laser output field, the phase diagram of the ellipticity angle and the spherical orientation angle is introduced. We find that, within the central spectral region of the dissipative soliton, the state of polarization evolves with frequency by tracing a uniform arc on the Poincaré sphere, whereas in the edges of the dissipative soliton spectrum, the state of polarization abruptly changes its path. Increasing cavity gain leads to spectral broadening, accompanied by a random scattering of the state of polarization of newly generated frequencies. Further increases of pump power result in dissipative soliton explosions, accompanied by the emergence of a new type of optical polarization rogue waves. These experimental results provide a deeper insight into the transient dynamics of dissipative soliton fiber lasers.

Acousto-optic interactions, employed in the ultrafast laser regulation, possess remarkable advantages for fast tuning performance in a wide spectral range. Here, we propose an ultrafast fiber laser whose wideband tunability is provided by an acousto-optic structure fabricated with an etched single-mode fiber. Because of the laser polarization conversion induced by the coupling between the core and cladding vector modes in the etched fiber, a band-pass characteristic of the acousto-optic interaction is achieved to effectively regulate the inner-cavity gain range. Cooperating with a saturable absorber based on single-wall carbon nanotubes (SWCNTs) with polarization robustness, a soliton operating state is achieved in the tunable erbium-doped fiber laser. By controlling the acoustical wave frequency from 1.039 to 1.069 MHz, this soliton laser can be conveniently tuned in a wide spectral range from 1571.52 to 1539.26 nm. Meanwhile, the laser pulses have near-transform-limited durations stably maintaining less than 2 ps at different wavelength channels, owing to the broadband nonlinear absorption of SWCNTs.