Advanced Photonics Research最新文献

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.

This study demonstrates the surface lattice resonance (SLR) laser utilizing asymmetric dual-metallic nanoparticle arrays, incorporating a high-refractive-index material, which exhibits a confinement factor of 16%, enhancing the coupling between metal and dielectric materials. Multiple quantum wells (MQWs) are integrated with plasmonic SLR in the proposed structure. Through theoretical design and experimental validation, the MQW plasmonic SLR laser exhibits excellent high Q-factor and stable operation at room temperature. This demonstration enhances laser performance and achieves low-threshold operation with a laser threshold as low as ≈2.39 MW cm⁻². This study's design of plasmonic SLR lasers further advances the realization of optoelectronic device applications.

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.

Gallium nitride (GaN)-based semiconductor laser diodes (LDs) have garnered significant attention due to their promising applications. However, high-power LDs face serious degradation issues that limit their practical use. This study investigates the degradation factors of 437 nm and 6.3 W LDs by comparing light–current–voltage (L–I–V) characteristics, transmission electron microscopy (TEM), cathodoluminescence (CL), and secondary ion mass spectroscopy (SIMS) before and after 1000-h aging. The diffusion of mirror coating from the resonant cavity surface is identified as a key factor contributing to high-power LD degradation, which has not been reported in milliwatt-level LDs. Meanwhile, the mechanisms behind the LD degradation are profiled and summarized together with the diffusion and other factors. On basis of the mechanism exploration, an anti-aging technology for high-power GaN-based LDs is developed by using aluminum nitride for passivation layer and sapphire materials for mirror film. This anti-aging technology has been verified, and a nearly ten-time degradation suppression is achieved from 1000 h. This study elucidates the degradation mechanisms of high-power GaN LDs and provides an effective technology to extend their lifespan, thereby prompting the practical applications of high-power LDs.

Optically pumped spintronic terahertz emitters (STEs) have, in less than a decade, strongly impacted terahertz (THz) source technology, by the combination of their Fourier-limited ultrafast response, their phononless emission spectrum and their wavelength-independent operation. However, the intrinsic strength of the inverse spin Hall effect governing these devices introduces a challenge: the optical-to-terahertz conversion efficiency is considerably lower than traditional sources. It is therefore primordial to maximize at least their electromagnetic efficiency independently of the spin dynamics at play. Using a rigorous time-domain treatment of the electromagnetic generation and extraction processes, an optimized design is presented and experimentally confirmed. With respect to the strongest reported spintronic THz emitters it achieves a 250% enhancement of the emitted THz field and therefore an 8 dB increase of emitted power. This experimental achievement brings STE close to the symbolic barrier of mW levels. The design strategy is generically applicable to any kind of ultrafast spin-to-charge conversion (S2C) system. On a broader level, our work highlights how a rigorous handling of the purely electromagnetic aspects of THz spintronic devices can uncover overlooked aspects of their operation and lead to substantial improvements.