title: Shaping of the end of a multimode optical fiber for efficient coupling light from a laser diode.
abstract: An entrance surface of a multimode optical fiber with the highest efficiency of coupling radiation from a laser diode is considered. The geometry of the surface is designed with the purpose of keeping a refracted ray inside the fiber with simultaneous minimization of the reflection coefficient in each point of the surface. As a good approximation to the ideal surface, the composite entrance surface of a cylinder-wedge shape is proposed. It has clearly improved the coupling efficiency as compared with that of the purely cylindrical surface. Analysis of the entrance surfaces is based on their transmission coefficients, depending on the incident ray direction.
authors.affiliation: Institute of Laser Physics SD RAS, 630090 Novosibirsk, Russia.
authors.forename: S B
authors.initials: SB
authors.lastname: Sevastianov
authors.forename: S M
authors.initials: SM
authors.lastname: Vatnik
authors.forename: A P
authors.initials: AP
authors.lastname: Mayorov