Light emitting element, reference light source and method for observing luminous body

A light-emitting element, in which a light whose emission angle distribution is one of Lambert's emission law or uniform Isotropic emission, is extracted from a light extraction opening window, and an in-plane distribution of a light intensity on a light extraction surface of the light extraction opening window is uniform, and which can be used as a reference light source when measuring an absolute light quantity of a weak light emitted from a luminous body which is a measurement object, the light-emitting element comprising:

• a lower clad layer;
• a light-emitting layer formed on the lower clad layer;
• an upper clad layer formed on the light-emitting layer;
• a transparent electrode formed on the upper clad layer;
• a cylindrical insulator provided so as to embed a groove formed at a depth that reaches at least the light-emitting layer from a surface side of the transparent electrode;
• a surface electrode formed on the transparent electrode, having an opening by exposing a surface of the transparent electrode surrounded by the insulator as the light extraction opening window for extracting a weak light and supposed to be the light extraction surface, and covering an entire circumference of an outer circumferential edge of the transparent electrode surrounded by the insulator;
• and
• a back electrode connected to the lower clad layer.