The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the coronavirus disease 2019 (COVID-19) worldwide pandemic. This unprecedented situation has garnered worldwide attention. An effective strategy for controlling the COVID-19 pandemic is to develop highly accurate methods for the rapid identification and isolation of SARS-CoV-2 infected patients. Many companies and institutes are therefore striving to develop effective methods for the rapid detection of SARS-CoV-2 ribonucleic acid (RNA), antibodies, antigens, and the virus. In this review, we summarize the structure of the SARS-CoV-2 virus, its genome and gene expression characteristics, and the current progression of SARS-CoV-2 RNA, antibodies, antigens, and virus detection. Further, we discuss the reasons for the observed false-negative and false-positive RNA and antibody detection results in practical clinical applications. Finally, we provide a review of the biosensors which hold promising potential for point-of-care detection of COVID-19 patients. This review thereby provides general guidelines for both scientists in the biosensing research community and for those in the biosensor industry to develop a highly sensitive and accurate point-of-care COVID-19 detection system, which would be of enormous benefit for controlling the current COVID-19 pandemic.

Fabrication of periodic transient-density structures in a gas jet with a boundary scale length approaching 10μm was demonstrated. This was achieved by passing an ultrashort high-intensity laser pulse through a patterned mask and imaging the mask onto the target plane. Gas/plasma density at the laser-irradiated regions drops as a result of hydrodynamic expansion following ionization and heating by the laser pulse. The fabrication of gas/plasma density structures with such a scheme is an essential step in the development of plasma photonic devices for applications in high-field physics.

We report continuous-wave laser operation at 698 nm in Pr 3 -doped LiYF 4 crystal using an InGaN laser diode emitting at 444 nm with a maximum output power of 760 mW. By suppressing the oscillation at 640 and 721 nm, a maximum output power of 156 mW at 698 nm was obtained in a single transverse mode with a slope efficiency as high as 48.7%. The beam quality factors M 2 in the x and y directions were measured to be 1.4 and 1.2, respectively.

The spatiotemporal optical vortex (STOV) is unique, owing to its phase singularity in the space–time domain, and it can carry transverse orbital angular momentum (OAM). Diffraction is a fundamental wave phenomenon that is well known for conventional light; however, studies on the diffraction of light with transverse OAM are limited. Furthermore, methods that enable the fast detection of STOVs are lacking. Here, we theoretically and experimentally study the diffraction behaviors of STOVs, which are different from those of conventional light. The diffraction patterns of STOV pulses that are diffracted by a grating exhibit multilobe structures with a gap number that corresponds to the topological charge. The diffraction rules of STOVs are also revealed. An approach for the fast detection of STOVs is provided using their special diffraction properties. This method has potential applications in fields that require fast STOV recognition, such as STOV-based optical communications.