This review presents a comprehensive overview of field‐programmable gate array (FPGA)‐based laser frequency stabilization systems employing modulation‐based spectroscopy techniques. The transition from traditional analog servo controllers to digital and hybrid FPGA‐based architectures is discussed, highlighting the advantages of FPGAs in terms of low latency, high bandwidth, flexibility, and long‐term stability. Particular emphasis is placed on modulation transfer spectroscopy, which has emerged as one of the most widely used and robust approaches for high‐precision laser frequency locking due to its background‐free error signals and reduced sensitivity to residual amplitude modulation. Representative system architectures, control strategies, and performance metrics reported in the literature are critically compared, with applications in atomic physics, quantum technologies, and high‐resolution spectroscopy. Finally, emerging directions such as adaptive digital control and machine‐learning‐assisted optimization are discussed as future perspectives for FPGA‐based laser stabilization systems.

Raman Amplification Raman amplification is a powerful method for selectively enhancing optical signals within specific spectral bands. In their Research Article (10.1002/adpr.202500164), Zhenxu Bai, Zhiwei Lu, and co-workers propose an adaptive Raman amplification scheme, employing diamond as the Raman gain medium, which alternates between Raman and energy-level gain stages to efficiently recycle residual pump energy. Through self-synchronizing and delay-tolerant pump recovery, it provides a robust and highly efficient strategy for high-power nonlinear optical amplification.

Nonlinear optical materials designed for mid‐infrared applications gain increasing interest in photonics and quantum‐optical research. However, many of these materials remain unexplored in the broad mid‐infrared range due to the limited availability of suitable equipment. Silver thiogallate (AgGaS 2 ) is one of the widely known nonlinear crystals used in mid‐infrared frequency‐conversion applications. While its transmission and refractive indices are well characterized up to 10.6 μm, dispersion properties beyond this wavelength remain unreported. In this work, a quantum‐optical approach is employed to determine the refractive indices of AgGaS 2 across an extended mid‐infrared wavelength range. Correlated photon pairs are generated in the crystal, where one photon in a pair is generated at a near‐infrared wavelength and the other in the mid‐infrared. Due to the correlations, detecting the spectrum of the near‐infrared photons allows inferring the crystal's dispersion properties in the mid‐infrared region up to 21 μm, without the need for infrared light sources or detectors. Sellmeier equations are further proposed that accurately describe both ordinary and extraordinary refractive indices across the entire transparency range of the crystal. The results are consistent with previously reported data below 10 μm and demonstrate the suitability of AgGaS 2 for frequency‐conversion processes over an extended wavelength range.

Hyperspectral imaging in the visible spectrum offers significant potential for diverse applications, but is often constrained by bulky hardware and limited robustness in low‐light conditions. To overcome these challenges, a simulation‐based proof‐of‐concept for a metasurface‐encoded single‐pixel hyperspectral imaging system (MESH) is presented, in which structured spatial modulation is combined with a compact set of 50 broadband metasurface filters designed using a binary pattern generation strategy to ensure low interfilter correlation. Hyperspectral datacubes comprising 301 channels from 400 to 700 nm are reconstructed via a sparsity‐constrained optimization algorithm, while a physics‐enhanced deep learning model is further introduced to enable fast and accurate recovery. Simulation results demonstrate that MESH achieves a spectral resolution of 1.17 nm. Even at a total compression ratio of 2.1%, the deep learning model maintains high reconstruction quality, with a peak signal‐to‐noise ratio of 30.96 dB, structural similarity of 0.8526, and spectral angle mapping of 0.0742 rad, indicating accurate intensity recovery, structural preservation, and spectral integrity. The present study provides a simulation‐based verification of feasibility and design guidelines, laying the groundwork for future experimental validation of the MESH system, which is expected to further demonstrate its practical applicability and performance for deployment in low‐light and resource‐constrained environments.