光子晶体面发射激光器（PCSEL）利用二维光子晶体光栅的布拉格共振实现面发射激光，具有其独特的优势，包括单模性能、在片测试、高功率、低发散角等。相比垂直腔面发射激光器（VCSEL），PCSEL有将近两倍的有源区光限制因子，展现出高速运行的潜力。本文探讨了PCSEL的基本结构和工作原理，并详细分析了影响PCSEL激光器实现高速性能的关键因素。随后，文章系统地介绍了近年来研究者们为实现PCSEL高速性能所做的努力，重点聚焦于通过增强PCSEL的面内限制来缩小激光腔，并提供了相关的研究方向和指导。

We report a wavelength-tunable multi-point pump scheme of the semiconductor disk lasers (SDLs). By designing an external cavity of SDL with an intra-cavity transmission grating, multiple pump gain regions share the same resonator. The effect of the intra-cavity grating on the output laser power, wavelength, and beam quality was investigated. The emission wavelength could be tuned over a bandwidth of ∼18nm. With multi-point pumping, we achieve the laser output power with almost no loss, and further improvement is limited by the thermal effect. The changes in the beam are due to the mode selectivity by the intra-cavity grating.

垂直腔面发射激光器(VCSEL)具有低成本、低阈值、高速率和低功耗等优点，在短距离光互连中有着重要的应用。随着大数据、超级计算机技术的发展，短距离光互连性能需求越来越高，从而对高速调制的850 nm VCSEL技术提出了更高要求。从带宽限制机理、调制新方法两方面详细回顾了高速850 nm VCSEL技术最新进展，对技术发展趋势进行了总结与展望。

Localized surface plasmon resonance (LSPR) of nanostructures and the interfacial charge transfer (CT) of semiconductor materials play essential roles in the study of optical and photoelectronic properties. In this paper, a composite substrate of Ag2S quantum dots (QDs) coated plasmonic Au bowtie nanoantenna (BNA) arrays with a metal–insulator–metal (MIM) configuration was built to study the synergistic effect of LSPR and interfacial CT using surface-enhanced Raman scattering (SERS) in the near-infrared (NIR) region. The Au BNA array structure with a large enhancement of the localized electric field (E-field) strongly enhanced the Raman signal of adsorbed p-aminothiophenol (PATP) probe molecules. Meanwhile, the broad enhanced spectral region was achieved owing to the coupling of LSPR. The as-prepared Au BNA array structure facilitated enhancements of the excitation as well as the emission of Raman signal simultaneously, which was established by finite-difference time-domain simulation. Moreover, Ag2S semiconductor QDs were introduced into the BNA/PATP system to further enhance Raman signals, which benefited from the interfacial CT resonance in the BNA/Ag2S-QDs/PATP system. As a result, the Raman signals of PATP in the BNA/Ag2S-QDs/PATP system were strongly enhanced under 785 nm laser excitation due to the synergistic effect of E-field enhancement and interfacial CT. Furthermore, the SERS polarization dependence effects of the BNA/Ag2S-QDs/PATP system were also investigated. The SERS spectra indicated that the polarization dependence of the substrate increased with decreasing polarization angles (θpola) of excitation from p-polarized (θpola=90°) excitation to s-polarized (θpola=0°) excitation. This study provides a strategy using the synergistic effect of interfacial CT and E-field enhancement for SERS applications and provides a guidance for the development of SERS study on semiconductor QD-based plasmonic substrates, and can be further extended to other material-nanostructure systems for various optoelectronic and sensing applications.

A modified spectral beam combining (SBC) approach based on double asymmetrical filters was proposed. By using this scheme, the high-order lateral modes at the edge of the far-field pattern can be suppressed in the external cavity, and the beam quality in the slow-axis direction was improved from 16.1 to 13.4 compared to the conventional SBC. In the meanwhile, the electrical-to-optical efficiency from the modified SBC was more than 40% with an output power of 34.1 W, which is similar to that of the conventional SBC.

Broad-area diode lasers usually supply high output power but low lateral beam quality. In this Letter, an on-chip combined angled cavity is proposed to realize narrow lateral far field patterns and high brightness. The influence of included angles, emitting facets on output power, and beam quality are investigated. It demonstrates that this V-junction laser is able to achieve a single-lobe far field at optimal cavity length with a 3.4 times improvement in brightness compared with Fabry–Perot (F-P) cavity lasers. The excited high-order modes at a high injection level reduce the brightness, but it is still 107% higher than that of F-P lasers.

A novel and simple polarization independent grating couplers is designed and analyzed here, in which the TE polarization and the TM polarization light can be simultaneously coupled into a silicon waveguide along the same direction with high coupling efficiency. For the polarization-insensitive grating coupler, the coupling efficiencies of two orthogonal polarizations light are more than 60% at 1550 nm wavelength based on our optimized design parameters including grating period, etching height, filling factor, and so on. For TE mode the maximum efficiency is ～72% with more than 30 nm 1 dB bandwidth, simultaneously, for TM mode the maximum efficiency is 75.15% with 40 nm 1 dB bandwidth. Their corresponding wavelength difference between two polarizations’ coupling peaks is demonstrated to be 35 nm. Polarization independent grating coupler designed here can be widely used in optical communication and optical information processing.