Patent ID: 7602823

Claim:
A light-emitting element comprising: a light amplification unit having a function of amplifying light; an external resonator connected to said light amplification unit, said external resonator comprising a planar light waveguide arranged inside said external resonator and a stress application unit which applies stress directly or indirectly to at least a partial region of said planar light waveguide; a stress control unit which controls a magnitude of the stress applied to said planar light waveguide by said stress application unit; and an emission state monitor that detects optical power of light transmitted from said planar light waveguide, wherein said stress application unit controls the magnitude of the stress on the basis of information from said emission state monitor, wherein said planar light waveguide has a spiral waveguide portion extending through a region where said stress application unit is arranged, and said stress application unit applies stress to the spiral waveguide portion.