A monolithic multicomponent system is proposed and implemented on a III-nitride-on-silicon platform, whereby two multiple-quantum-well diodes (MQW-diodes) are interconnected by a suspended waveguide. Both MQW-diodes have an identical low-In-content InGaN/Al_0.10Ga_0.90N MQW structure and are produced by the same fabrication process flow. When appropriately biased, both MQW-diodes operate under a simultaneous emission-detection mode and function as a transmitter and a receiver at the same time, forming an in-plane full-duplex light communication system. Real-time full-duplex audio communication is experimentally demonstrated using the monolithic multicomponent system in combination with an external circuit.

An spoof surface plasmon polaritons (SSPPs) bandpass filter (BPF) supported by trident-shaped complementary grooves is proposed in this letter. Compared with the traditional rectangular-groove SSPP unit cell, the vertical size of the proposed SSPP unit cell is reduced by 40% under the condition of the same asymptotic frequency. Then, a matching feeding structure is introduced by designing microstrip-to-slotline transition (MST) and thus a low cut-off frequency can be obtained. The low cut-off frequency of the passband is determined by the MST structure and the high cut-off frequency of the passband is determined by the SSPP structure. Consequently, a BPF with controllable frequency band and wide stopband suppression is formed by the MST structure and the proposed SSPP structure. Finally, the designed BPF was fabricated and measured. Both numerical and experimental results suggest good filtering performance of the proposed BPF in the frequency band from 2.1 to 8 GHz.

A surface plasmon resonance (SPR) sensor based on exposed core micro-structured optical fiber (EC-MOF) for temperature self-compensated salinity detection is proposed. The sensing channel is fabricated by sequentially coating indium tin oxide (ITO) and Au layers at the exposed region of the fiber core. Benefiting from the large dynamic refractive index (RI) range of ITO induced by dispersion, two separated SPR peaks with equal intensity can be excited at visible spectrum by Kretschmann configuration and near-infrared spectrum by Otto configuration. The RI sensing performance at 1.33–1.39 is investigated and optimized using finite element method, with maximum wavelength sensitivities of 2000 nm/RIU and 3000 nm/RIU, respectively. The distinct RI responses of two SPR peaks make the dual-parameter demodulation realizable, which shows great potential in multiplex or self-compensated sensing applications. The temperature self-compensated salinity sensing ability is demonstrated with high sensitivity of 4.45 nm/% and a temperature compensation coefficient of −0.12%/°C. To the best of our knowledge, this is the first time temperature self-compensation of fiber SPR sensors with a single sensing channel and the single demodulation method has been realized.

Aluminum-rich p-AlGaN electron blocking layers (EBLs) are typically used for preventing overflow of electrons from the active region in AlGaN-based deep ultraviolet (DUV) laser diode (LD). However, these cannot effectively prevent electron leakage and form barrier layers, which affects the hole injection efficiency. Herein, the traditional p-AlGaN EBL in LD is replaced with an undoped BGaN EBL. The undoped BGaN EBL LD increases the effective barrier height of the conduction band to prevent the leakage of electrons and decreases the energy loss caused by the polarization induced electric field, enhancing the hole injection. The slope efficiency of the undoped BGaN EBL LD is 289% higher than that of the highly doped AlGaN EBL LD, and its threshold current is 51% lower. Therefore, the findings of this study provide insights for solving the problems of electron leakage and insufficient hole injection in high-performance and undoped EBL DUV LDs.

GaN-based devices have grown rapidly in recent decades, due to their important research value and application prospects. There is a desire to monolithically integrate different GaN devices into a single chip for the development of future optoelectronic systems with low power consumption. In addition to improved multifunctional performance, a miniature integrated system can result in a significant reduction in material costs, processing costs, and packaging costs. In view of such prospects, we propose monolithic, top-down approaches to build III-nitride transmitter, modulator, waveguide, beam splitter, receiver, and monitor as a single unit onto a conventional GaN-on-silicon wafer without involving regrowth or postgrowth doping. Data communication among these components is realized through light propagation, opening up horizons for GaN optoelectronic systems on a chip.

Optical fiber curvature sensors have been considered as a promising option for human motion detection due to its good toughness, bending flexibility and anti-electromagnetic interference. However, for wearable devices, the miniature configuration is preferred, and a high integration of the light emitter, receiver and guided fiber is essential to configure the miniaturized sensing system. Here, we present a miniaturized curvature sensing system by integrating a GaN-based optoelectronic chip with the plastical optical fiber (POF). The light emitter and detector are fabricated on a GaN-on-sapphire wafer to form a tiny chip sized at 2.5 $$\times$$× 1.5 mm². The on-chip photodetector (PD) effectively senses the reflected light intensity, extracting information on the fiber bending deformation. A compact curvature sensing system is demonstrated for finger motion detection with movement angles of 30–90° and frequencies of 0.4, 1, and 1.6 Hz. The results show that the monolithically integrated LED and PD chip can be combined with the POF with reliable operation. The demonstration of the monolithically integrated optoelectronic device suggests a promising potential technology for future wearable fiber optical sensor system.