Abstract: A semiconductor laser element includes a substrate and a semiconductor stack. The semiconductor stack includes an N-side semiconductor layer, an active layer, a P-side semiconductor layer, and a P-type contact layer. The semiconductor stack includes two end faces. Laser light resonates between the two end faces. The semiconductor stack includes: a ridge portion; and a bottom portion surrounding the ridge portion in a top view of the semiconductor stack. The ridge portion protrudes upward from the bottom portion, is spaced apart from the two end faces, and includes at least a portion of the P-type contact layer. A current injection window is provided only on the ridge portion out of a top face of the semiconductor stack, the current injection window being a region into which a current is injected. A distance from a top face of the active layer to the bottom portion is constant.

Abstract: A ScAlMgO4 single crystal substrate having less collapse of crystal orientation, and a method for producing the single crystal substrate. A ScAlMgO4 single crystal substrate is provided, wherein, when a center of the substrate is designated as coordinates (0,0) and a measurement beam width is set to 1 [mm]×7 [mm] to conduct analysis according to an X-ray diffraction method at respective coordinate positions of (x?m,0) to (xm,0) at an interval of 1 [mm] in an x-axis direction and (0,y?n) to (0,yn) at an interval of 1 mm in a y-axis direction, wherein m and n are each an integer falling within the range so that the measurement beam is not stuck out from the substrate, a worst value of a full width at half maximum of a rocking curve at each of the coordinate positions is less than 20 [sec.].

Abstract: A ScAlMgO4 single crystal substrate having less collapse of crystal orientation, and a method for producing the single crystal substrate. A ScAlMgO4 single crystal substrate is provided, wherein, when a center of the substrate is designated as coordinates (0,0) and a measurement beam width is set to 1 [mm]×7 [mm] to conduct analysis according to an X-ray diffraction method at respective coordinate positions of (x?m,0) to (xm,0) at an interval of 1 [mm] in an x-axis direction and (0,y?n) to (0,yn) at an interval of 1 mm in a y-axis direction, wherein m and n are each an integer falling within the range so that the measurement beam is not stuck out from the substrate, a worst value of a full width at half maximum of a rocking curve at each of the coordinate positions is less than 20 [sec.].