Advanced Photonics Research最新文献

In the More-than-Moore era, the explosive growth of data and information has driven the exploration of alternative non-von Neumann computational paradigms. Photonic neuromorphic computing has emerged as a promising approach, offering high speed, wide bandwidth, and massive parallelism. Herein, a high-resolution optical convolutional neural network (OCNN) is introduced using phase-change material Ge₂Sb₂Te₅ (GST)-based microring hybrid waveguides. This on-chip optical computing platform integrates GST into photonic devices, enabling versatile programming and in-memory computing capabilities. Central to this platform is a photonic convolutional computational kernel, constructed from photonic switching cells embedded with GST on a microring resonator. This programmable photonic switch leverages the refractive index modulation during the GST phase transition to achieve up to 64 discrete levels of transmission contrast, suitable for representing matrix elements in neural network algorithms with 6-bit resolution. Using these matrix elements, an OCNN capable of performing parallelized image edge detection and digital recognition tasks with high accuracy is demonstrated. The architecture is scalable for large-scale photonic neural networks, offering ultrahigh computational throughput, a compact design, complementary metal-oxide-semiconductor-compatible fabrication, and broad bandwidth.

Supercontinuum (SC) sources covering near-infrared and midinfrared region have attracted enormous interest and found significant applications in tissue imaging, sensing, spectroscopy, defense, and environmental monitoring. Herein, an 8.45 W all-fiber ultraflat SC source with a spectral range of 1.01–4.05 μm using a flat high-power 1.9–2.7 μm SC fiber source to pump a piece of fluorotellurite fiber is presented. The SC spectrum exhibits a 3 dB bandwidth of 1850 nm, ranging from 1870 to 3720 nm, and a 10 dB bandwidth of 2770 nm, ranging from 1120 to 3890 nm. The measured power stability is 0.19% (root mean square) for 5 h of continuous operation, proving the excellent power stability of the system. To the best of knowledge, the SC spectrum exhibits the widest reported 3 and 10 dB bandwidths for 1–4 μm SC sources.

Metasurfaces have opened doors to combining multiple photonic functionalities in a single compact device. In particular, the ability to generate short terahertz (THz) pulses with precise wavefront engineering in a single THz metasurface redefined the role metasurfaces can play in THz systems. Here, an InAs metalens emitter which generates and focuses a THz pulse beam is demonstrated using a 130 nm thick InAs metasurface designed as a binary-phase Fresnel zone plate. The THz beam is focused to a spot of ≈430 μm at 1 THz with a short focal length of 5 mm and large numerical aperture of 0.5. Nanoscale InAs Mie resonators comprising the metasurface enable THz generation with an amplitude as high as 20 times compared to plasmonic THz emitters and several times compared to a 1 mm thick ZnTe crystal. This InAs metasurface emitter provides a new paradigm for designing THz imaging, spectroscopy, and communication systems, where THz beam generation and shaping are performed with a single device without compromising the generation efficiency, while eliminating losses and avoiding limitations of phase matching of conventional nonlinear optics approaches.

A full numerical study combining artificial intelligence (AI) methods and electromagnetic simulation software on a multilayered structure for radiative cooling (RC) is investigated. The original structure is made of SiO₂/Si nanometer-thick layers that make a Bragg mirror for wavelengths in the solar irradiance window (0.3–4 μm). The structures are then optimized in terms of the calculated net cooling power and characterized via the reflected and absorbed incident light as a function of their structural parameters. This investigation provides with optimal designs of beyond-Bragg, all-dielectric, ultra-broadband mirrors that provide net cooling powers in the order of ≈100 W m⁻², similar to the best-performing structures in literature. Furthermore, it explains AI's success in producing these structures and enables the analysis of resonant conditions in metal-free multilayers with unconventional layer thickness distributions, offering innovative tools for designing highly efficient structures in RC.

The compact and broadband optical switch with a large port count is demanded with the increasing communication capacity. In this article, a universal method for modeling the 1 × N switch using multimode interferometer (MMI) through transmission matrixes is proposed. Herein, the reasons for the narrowing of the operating bandwidth switch are analyzed. As a proof of concept, a wide bandwidth 1 × 4 switch, which has an insertion loss lower than 23.7 dB, and a cross talk better than −10 dB at 1550 nm are simulated, designed, and fabricated. The cross talk throughout the C band is lower than −8.5 dB. According to the experimental result, the 1 × 4 switch with four-equal-length modulating arms shows a 32 nm bandwidth for −10 dB cross talk which is 13 times larger than traditional switch. The switch realizes a multi-port logic optical switch by modulation. The 1 × N switch based on the generalized Mach–Zehnder interferometer (GMZI) structure reduce the footprint significantly compared with the 1 × N switch consisting of a 1 × 2 switch cascade. It is believed that 1 × N switch based on GMZI structures is a promising solution to increase integration density.

2D Layered Superconductors

In article number 2400045, Kaveh Delfanazari showcases methods for the realization of ultrafast terahertz (THz) metamaterial photonic switches on a few nanometer-thick layered high-temperature superconductor van der Waals (vdWs). The metamaterial array offers active modulation of THz amplitude and phase with an ultrafast-picosecond-switching timescale. The device holds promise for the development of future THz communication circuits and systems operating at cryogenic temperatures.

Core–Shell Particles

Essential features of functional optical materials are their interaction with light and underlying structures. In article number 2400091, Markus Gallei and co-workers report the combination of structural colors with cellulose, a renewable and biodegradable biopolymer. The latter acts as reinforcement agents, maintaining the polymer opal film’s structural color and mechanochromic material behavior.

Polymer-Network Liquid Crystals

In article number 2300340, Dan Luo, Kun-Lin Yang, and co-workers show that after partially completed photopolymerization, the polymer network liquid crystal undergoes a secondary polymerization to form an isotropic polymer network when it is heated beyond its clearing point, resulting in an irreversible optical appearance change from transparent to cloudy. It enables applications such as a heating stopwatch and oxygen sensing.

Coherent Perovskites Emitters

In article number 2400033, Kwangdong Roh and co-workers provide a comprehensive overview of the historical progress in perovskite lasers and light-emitting didoes, along with important design considerations essential for their development.

Owing to their excellent optoelectronic properties, halide perovskites (HPs) have garnered significant attention in the field of optoelectronics. However, conventional HPs-based optoelectronic devices primarily are fabricated using solution-based processes, implying that extremely time-consuming needs to individually synthesize their composition-dependent optoelectronic properties. This study demonstrates the feasibility of combining first-principles simulations with combinatorial synthesis, comparing the effects of HP properties on optoelectronic devices using this combined approach. The first-principles simulations confirm that increasing the ratio of small halide ions increased the band gap by k·p perturbation theory and harmonic oscillator models. By fabricating HP thin films with compositional gradients using combinatorial synthesis, it is confirmed that an increase in band gap corresponds to a decrease in static relative permittivity. Furthermore, HP-based optoelectronic devices are fabricated to measure their photoelectric conversion efficiency and responsivity based on the simulated and measured relative permittivity, including time-resolved photoluminescence. The findings demonstrate the influence of the relative permittivity on device performance, elucidating the relationship between band structure and relative permittivity. Therefore, in this study, the potential of combining first-principles simulations with combinatorial synthesis is confirmed by comparing the relative permittivity characteristics of optoelectronics developed using this combined approach.