OPTICAL FIBER COUPLING SYSTEM

摘要

PROBLEM TO BE SOLVED: To propagate light to an optical fiber with high efficiency by converting the light which is made incident and is made into clad mode light of the light emitted from an exit end toward a free space to the propagation mode light propagating in the same direction by the diffraction grating in the vicinity of the incident end of the optical fiber. SOLUTION: The laser beam emitted from the exit end 105 of a semiconductor laser 10 emitted to the free space by spreading at a prescribed spreading angle and is made incident on the incident end 203 of the optical fiber 20. The optical fiber 20 is a wire of a small diameter formed of a core part 201 and a clad part 202 of a low refractive index around the core part to a concentric shape and propagates the light into the core part 201 while reflecting totally at the boundary surface between the core part 201 and the clad part 202. The diffraction grating 204 is formed in the core part 201 near the incident end 203 of the optical fiber 20. The clad mode light is converted to the propagation mode light propagating in the same direction by the diffraction grating 204.