Abstract: A method of fabricating a nitride-based semiconductor device capable of reducing contact resistance between a nitrogen face of a nitride-based semiconductor substrate or the like and an electrode is provided. This method of fabricating a nitride-based semiconductor device comprises steps of etching the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure and thereafter forming an n-side electrode on the etched back surface of the first semiconductor layer.

Abstract: An SHG device wherein a channel is formed on a part of a waveguide layer; and the thickness of the waveguide layer is set so that the refractive index of the channel for a fundamental is greater than that for an SH (second harmonic) and the refractive index of portions on the both sides of the channel for the SH is greater than that for the fundamental, thereby accomplishing the phase matching between the fundamental and the SH, which satisfies the conditions that an output power of 2 mW or more which is sufficient for reading signals from an optical disk, that the optical intensity distribution at a light emitting end has a single peak, that the optical spot diameter at a light emitting end is small enough, and that the wavelength of the output is in the blue region.