LIGHT SOURCE-OPTICAL FIBER COUPLER

摘要

PROBLEM TO BE SOLVED: To combine a semiconductor laser and a single mode optical fiber with a small loss by reducing the vignetting of laser-emitted light. SOLUTION: In a light source-optical fiber coupler, the diffused light flux emitted from a light source (e.g. a semiconductor laser chip 10) is coupled with the end surface of the optical fiber (e.g. a single mode optical fiber 16) with a graded refractive index rod lens 14. In the graded refractive index rod lens, the end surface at the side of the light source is of a convex spherical shape, and the end surface at the side of the optical fiber is planar. The light source (a laser chip) and graded refractive index rod lens are held with a housing in a state that they are disposed close to each other. The distance of the laser chip surface and the graded refractive index rod lens end surface is set to 0.3 mm or smaller, more preferably to within the limits of about 0.2-0.25 mm.