arXiv subjects

Shu-Chun Chu

Publications and source records attributed to Shu-Chun Chu.

3 recordsLinked to original sources

arXiv2025

A polarization-Insensitive Broadband Achromatic Metalens with High Efficiency in Ultraviolet-C band

A metalens is composed of an array of artificially designed meta-atoms which can manipulate the phase, polarization and amplitude of light making it an excellent component for wavefront modulation. In this study, we design an transmittive achromatic metalens (NA equals to 0.05) composed of sapphire substrate and cross-shape silica meta-atom array operating across the entire ultraviolet C (UVC) band (200 to 280 nm) for all incident polarization through numerical simulation. It is shown that the device achieves an average focusing efficiency of 75% with a focal shift of less than 10% across the bandwidth and successfully demonstrates that is polarization-free. The device is expected to perform effectively in ultraviolet imaging and hold great potential for space-based astronomical observations.

physics.optics↗

arXiv2025

Inverse-Designed Phase Prediction in Digital Lasers Using Deep Learning and Transfer Learning

Digital lasers control the laser beam by dynamically updating the phase patterns of the spatial light modulator (SLM) within the laser cavity. Due to the presence of nonlinear effects, such as mode competition and gain saturation in digital laser systems, it is often necessary to rely on specifically manually tailored approach or iteration processes to find suitable loaded phases in Digital lasers. This study proposes a model based on Conditional Generative Adversarial Networks (cGAN) and a modified U-Net architecture, with designed loss functions to inverse design the loaded phases. In this work, we employ deep neural networks to learn the nonlinear effects in simulated L-shape digital lasers, enabling the prediction of SLM-loaded phases for both analytical and non-analytical arbitrary structured light fields. The results demonstrate superior performance on non-analytical light fields compared to the current methods in L-shape Digital lasers. Furthermore, a transfer learning strategy is introduced, allowing knowledge obtained from one class of structured beams to be effectively reused for another, thereby enhancing generalization and improving performance under limited training data. Importantly, this method, the first proposed learning framework for digital lasers, is not limited to the L-shaped digital lasers discussed in this study, providing an efficient alternative for generating structured light in other digital laser systems.

physics.optics↗

arXiv2008

Spontaneous Generation of Vortex Array Beams from a Thin-Slice Solid-State Laser with Wide-Aperture Laser-Diode Pumping

We studied complex lasing pattern formations in a thin-slice solid-state laser with wide-aperture laser-diode end-pumping. Radial and rectangular vortex arrays were found to be formed in a controlled fashion with symmetric and asymmetric pump beam profiles, respectively. Most of these vortices exhibited single-frequency oscillations arising from a spontaneous process of transverse mode locking of nearly degenerate modes assisted by the laser nonlinearity. Single-frequency rectangular array beams consisting of a large number of vortices, e.g., closely packed 36 or 46 vortex pixels, were generated, originating from Ince-Gaussian modes excited by the asymmetric pumping.

physics.optics↗