The world‐wide spreading of coronavirus disease (COVID‐19) has greatly shaken human society, thus effective and fast‐speed methods of non‐daily‐life‐disturbance sterilization have become extremely significant. In this work, by fully benefitting from high‐quality AlN template (with threading dislocation density as low as ≈6×10 8 cm −2 ) as well as outstanding deep ultraviolet (UVC‐less than 280 nm) light‐emitting diodes (LEDs) structure design and epitaxy optimization, high power UVC LEDs and ultra‐high‐power sterilization irradiation source are achieved. Moreover, for the first time, a result in which a fast and complete elimination of SARS‐CoV‐2 (the virus causes COVID‐19) within only 1 s is achieved by the nearly whole industry‐chain‐covered product. These results advance the promising potential in UVC‐LED disinfection particularly in the shadow of COVID‐19.

Quantum key distribution is a matured quantum science and technology. Over the last 20 years, there has been substantial research and development in this area. Recently, silicon technology has offered tremendous promise in the field for improved miniaturization of quantum key distribution through integrated photonic chips. We expect further progress in this area both in terms of protocols, photon sources, and photon detectors. This review captures some of the recent advances in this area.

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Recent progress in quantum nanophotonics brings novel ways for manipulating single photons in various nano-waveguides. Among them, one promising approach is to use optical nanofibres (ONFs), tapered optical fibres with sub-wavelength diameter waists. Here, we develop a hybrid system of an ONF and a single quantum dot (QD) operated at cryogenic temperatures. We deposit a single colloidal CdSe QD on an ONF waist and observe emitted photons through the fibre guided modes. We systematically investigate emission characteristics for both the neutral exciton and charged exciton (trion) for one specific QD. We quantitatively show that the trion at cryogenic temperatures acts as an excellent quantum emitter for the ONF and QD hybrid system. The present ONF/QD hybrid system at cryogenic temperatures paves the way for quantum information technologies for manipulating single photons in fibre networks.

Ultraviolet-C light-emitting diodes (UVC-LEDs) have great application in pathogen inactivation under various kinds of situations, especially in the fight against COVID-19. Unfortunately, its epitaxial wafers are so far limited to a size of 2 inches, which greatly increases the cost of massive production. In this work, a 4-inch crack-free high-power UVC-LED wafer is reported. This achievement relies on a proposed strain-tailored strategy, where a 3D to 2D (3D-2D) transition layer is introduced during the homo-epitaxy of AlN on the high temperature annealed (HTA)-AlN template, which successfully drives the original compressive strain into a tensile one and thus solves the challenge of realizing a high-quality Al 0.6 Ga 0.4 N layer with a flat surface. This smooth Al 0.6 Ga 0.4 N layer is nearly pseudomorphically grown on the strain-tailored HTA-AlN template, leading to 4-inch UVC-LED wafers with outstanding performances. The strategy succeeds in compromising the bottlenecked contradictory in producing a large-sized UVC-LED wafer on pronounced crystalline AlN template: The compressive strain in HTA-AlN allows for a crack-free 4-inch wafer, but at the same time leads to a deterioration of the AlGaN morphology and crystal quality. The launch of 4-inch wafers makes the chip fabrication process of UVC-LEDs match the mature blue one, and will definitely speed up the universal application of UVC-LED in daily life.

Based on the polarization switching mechanism in an optically injected vertical cavity surface emitting laser (VCSEL), and the new electro-optic modulation theory, we propose a novel approach to implement optoelectric logic gates. Here, the two linearly polarized lights from the output of the laser are considered as two logic outputs. Under the electro-optic modulation, one of the logic outputs is the NOT operation with the other one. With the same logic input signal, we perform various digital signal processing (AND, OR, XNOR, NAND, NOR and XOR) in the optical domain, controlling the logic operation of the applied electric field between the two logic input signals. On this basis, the logic operation of half-adder is further implemented.

Realization of fully integrated silicon photonics has been handicapped by the lack of a reliable and efficient III-V light source on Si. Specifically, electrically pumped continuous wave (CW) lasing and operation sustainable at high temperatures are critical for practical applications. Here, we present the first electrically pumped room temperature (RT) CW lasing results of 1.55 μm quantum dash (QDash) lasers directly grown on patterned on-axis (001) Si using metal organic chemical vapor deposition (MOCVD). Adopting a dash-in-well structure as the active medium, the growth of QDash was optimized on an InP on Si template. Incorporating the advantages of the optimized material growth and device fabrication, good laser performance including a low threshold current of 50 mA, a threshold current density of 1.3 kA/cm2 and operation at elevated temperature up to 59 °C in CW mode was achieved. Comparison of lasers grown on Si and native InP substrates in the same growth run was made. Based on the laser characteristics measured at room temperature and elevated temperatures, the QDash quality on the two substrates is comparable. These results suggest that MOCVD is a viable technique for lasers on Si growth and represent an advance towards silicon-based photonic-electronic integration and manufacturing.

A photodetector (PD) converts optical signals into electrical ones and is widely used in optical interconnect. High-speed PDs are in high demand as they are necessary to meet requirements of large-capacity optical interconnect. Many high-performance PDs with various absorption materials and structures are demonstrated on silicon photonics platform, including germanium (Ge) PDs, germanium tin (GeSn) PDs, heterogeneous integrated III-V PDs, all silicon (Si) PDs, 2D material PDs, etc. These kinds of PDs continue to set new records of speed and open an era of ultrahigh-speed optical interconnect. A comprehensive summary of the state-of-the-art high-speed PDs on silicon photonics platform is necessary and meaningful. In this review, the basic metrics and key process technologies for the PDs are introduced, and various types of high-speed PDs based on silicon photonics platform are reviewed and discussed. Furthermore, the summary and perspectives are provided. It is hoped that this review can provide readers more insights into recent advances in high-speed PDs on silicon photonics platform and contribute to the further development.