Polarity Inversion of Nitride Semiconductors and Application to Deep-Ultraviolet Photonic Devices

Abstract

  III-nitride semiconductors are promising nonlinear optical crystals due to a wide bandgap energy, a high nonlinear optical constant, enabling broadband operation of nonlinear optical effects such as wavelength conversion and optical modulation in the deep ultraviolet (DUV) wavelength. Integration of nitride-based wavelength conversion with blue laser diodes enables a compact and highly-efficient coherent source in the DUV wavelength. This paper describes the principle of wavelength conversion and nonlinear optical crystals used in the ultraviolet region. Subsequently, focusing on nitride semiconductors as nonlinear optical crystals, polarity inversion methods, evaluation methods, and device applications are described.