arXiv subjects

Wei Wen Wong

Publications and source records attributed to Wei Wen Wong.

4 recordsLinked to original sources

arXiv2026

Self-powered InAs nanowire detector arrays for extended-SWIR spectrometry at room temperature

Spectral sensing in the extended shortwave infrared (e-SWIR) is important for molecular analysis, infrared imaging, and machine vision, motivating the development of compact spectrometers for broader applications. However, conventional commercial off-the-shelf spectrometers in this wavelength region are expensive and bulky due to their reliance on external dispersive optics/filters and/or cryogenic accessories. Other emerging computational spectrometers are based on Si and InGaAs photodetectors that remain focused on the visible and near-infrared, with few detector platforms operating in the e-SWIR regime that simultaneously provide broadband sensitivity, low-noise room-temperature operation, and diverse spectral signatures for accurate identification and reconstruction. Here, we report a room-temperature e-SWIR computational spectrometer based on InAs/InP core-shell nanowire photodetector arrays with geometry-encoded spectral responses. The detectors exhibit self-powered broadband photoresponse across the 1--3 $μ$m range, with responsivity up to 0.215 A W$^{-1}$, detectivity up to $1.6 \times 10^{9}$ cm Hz$^{1/2}$ W$^{-1}$, and microsecond response times. The excellent detector performance is leveraged to demonstrate filter-free spectral reconstruction using a compact multipixel photodetector array device. This enables high-accuracy molecular absorption spectrum reconstruction and hyperspectral imaging. Our results indicate that InAs nanowire arrays are a promising platform for compact computational spectrometry and imaging in the e-SWIR at room temperature.

physics.optics↗

arXiv2026

Closing the Loop in Epitaxy with Machine Learning: Joint Optimization of Growth and Geometry in On-Chip Lasers

Achieving device-to-device reproducibility is a critical bottleneck for scalable photonic integrated circuits, as subtle variations in bottom-up epitaxial growth and fabrication severely limit yield. We present a machine learning workflow for III-V multi-quantum well microring lasers that first optimizes growth and geometry parameters via multi-objective Bayesian optimization, then leverages variational autoencoders (VAEs) to attribute residual device-to-device variability to its underlying sources. By explicitly targeting threshold variance alongside absolute performance, we demonstrate 100% lasing yield across all designs. The optimized multi-quantum well microring laser fields achieved a median lasing threshold of $16~μ\mathrm{J}\,\mathrm{cm}^{-2}\,\mathrm{pulse}^{-1}$, a $73\%$ reduction in threshold variance relative to the previously reported best values, and a median emission wavelength of $1333~\mathrm{nm}$, in the telecommunications O-band. Furthermore, to diagnose residual performance dispersion under nominally identical conditions, VAEs were used to isolate the key components of device morphology that impact performance. This analysis successfully decoupled geometric from material disorder, quantitatively linking previously unmeasured morphological variations to population-level threshold fluctuations. This data-driven workflow bridges the gap between fundamental epitaxy and reliable manufacturing, establishing a generalizable blueprint for designing and yield-optimizing complex, non-linear optoelectronic devices.

physics.optics↗

arXiv2025

Far-field directionality control of coupled InP nanowire lasers

Nanowire (NW) lasers hold great promise as compact, coherent on-chip light sources that are crucial for next-generation optical communication and imaging technologies. However, controlling their emission directionality has been hindered by the complexities of lasing mode engineering and fabrication. Here, we demonstrate spatially-engineered far-field emission from vertically emitting InP NW lasers by establishing precise control over the optical coupling between site-selective NWs, without relying on post-epitaxy transfer and alignment processes. Leveraging this process capability, we design and grow NW pairs and triplets that lase in the TE01 waveguide mode. We then demonstrate the ability to modify their far-field emission profiles from the signature doughnut-like emission to a double-lobed emission profile by changing their optical coupling gap, evidenced by closely matching simulation and experimental profiles. Moreover, through numerical simulations, we show further enhancement in the far-field directionality by arranging the NW laser pairs in a periodic array, demonstrating the feasibility of a directional lasing metasurface. Our results provide a foundation for efficient integration of coherent light generation and beam steering in on-chip light sources.

physics.optics↗

arXiv2024

Accelerated Design of Microring Lasers with Multi-Objective Bayesian Optimization

On-chip coherent laser sources are crucial for the future of photonic integrated circuits, yet progress has been hindered by the complex interplay between material quality, device geometry, and performance metrics. We combine high-throughput characterization, statistical analysis, experimental design, and multi-objective Bayesian optimization to accelerate the design process for low-threshold, high-yield III-V microring lasers with room-temperature operation at communication wavelengths. We demonstrate a 1.6$\times$ reduction in threshold over expert-designed configurations, achieving a 100% lasing yield that emits within the O-band with a median threshold as low as 33$μ$J cm$^{-2}$ pulse$^{-1}$.

physics.optics↗