Photonic crystal surface-emitting lasers (PCSELs) are an unprecedented type of semiconductor laser that can achieve single longitudinal- and lateral-mode oscillation even over areas of millimeters in diameter. Their brightness, defined as power per unit area per unit solid angle, is expected to be increased up to the range of 1~10GWcm-2sr-1, which is comparable to those of gas lasers and fiber lasers. Also, PCSELs have additional functions, including the generation of beams with various patterns and polarizations, and they can even achieve electric two-dimensional beam scanning. Material systems for PCSELs are currently being expanded to not only InGaAs/GaAs (900-1000nm), but also InGaAsP/InP (1.3-1.55um) and even InGaN/GaN (400-530nm). LiDAR is discussed as one example of the applications of PCSELs. PCSELs will become a key light source in the forthcoming ultra-smart Society 5.0, which includes smart mobility and smart processing.
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