The image on the cover of Photonics Research Volume 9, Issue 4, demonstrates temperature tunable spectral broadening using a nonlinear ultra-silicon-rich nitride device consisting of a 3-mm-long cladding-modulated Bragg grating and a 7-mm-long nonlinear channel waveguide. Provided by Y. Cao et al., researchers from Singapore University of Technology and Design, Ecole Polytechnique Fédérale de Lausanne, Institute of Microelectronics, A*STAR and The University of Sydney, the image is based on the research presented in their article "Thermo-optically tunable spectral broadening in a nonlinear ultra-silicon-rich nitride Bragg grating", Photonics Research 9(4) 04000596, doi 10.1364/PRJ.411073.
The image on the cover of Chinese Optics Letters Volume 19, Issue 4, indicates that a new type of optical bi-layer metasurface system is designed and studied, which is based on subwavelength metal slit arrays with phase-gradient modulation, referred to as metagratings (MGs). Provided by Q. Shi et al., researchers from Soochow University, Nanjing University of Aeronautics and Astronautics and North University of China, the image is based on the research presented in their article "Optical beam splitting and asymmetric transmission in bi-layer metagratings", Chinese Optics Letters 19(4) 042602, doi 10.3788/COL202119.042602.
The image on the cover of Photonics Research Volume 9, Issue 3, presents a new imaging modality, deep compressed imaging via optimized-pattern scanning, which can significantly increase the acquisition speed for a single-detector-based imaging system. Provided by K. Zhang, J. Hu and W. Yang, researchers from University of California, the image is based on the research presented in their article "Deep compressed imaging via optimized pattern scanning", Photonics Research 9(3) 03000B57, doi 10.1364/PRJ.410556.
The image on the cover of Chinese Optics Letters Volume 19, Issue 3, indicates that under near-ultraviolet excitation at 394 nm, optimal Sr2LaTaO6: 0.2Eu3+ phosphors emitted high-brightness red light around 613 nm with the International Commission on Illumination chromaticity coordinates (0.650, 0.349). Provided by Z. Zhang et al., researchers from Taiyuan University of Technology, the image is based on the research presented in their article "High-brightness red-emitting double-perovskite phosphor Sr2LaTaO6: 0.2Eu3+ with high color purity and thermal stability [Invited]", Chinese Optics Letters 19(3) 030003, doi 10.3788/COL202119.030003.