Single longitudinal mode pumped optical waveguide laser arrangement

Abstract

An optical waveguide laser arrangement includes a solid optical waveguide having a waveguiding portion that extends along an axis between two spaced regions of the optical waveguide and is of a material capable of emitting stimulated light upon excitation by pumping light that is launched into the optical waveguide for axial propagation through the axially spaced regions of the optical waveguide. Two reflectors are provided, each being disposed at one of the axially spaced regions of the optical waveguide to delimit a laser resonator. At least one of the reflectors is constituted by a Bragg grating consisting of a multitude of axially consecutive periodic perturbations in the refractive index of the respective one of the axially spaced regions that cumulatively reflect the stimulated light at a reflectivity that decreases for adjacent longitudinal modes of the stimulated light with increasing deviation from a central wavelength. The axial length of the laser resonator, the reflectivity of the Bragg grating and the gain of the excitable material are so coordinated with one another as to sustain lasing in only a single longitudinal mode.

Claims

1. In an optical waveguide laser arrangement including a solid optical waveguide having a gain portion that extends along an axis between two axially spaced reflectors disposed along the optical waveguide, said gain portion being of an excitable material which emits stimulated light upon excitation by pumping light, means for launching the pumping light into the optical waveguide for axial propagation along the optical waveguide, the two reflectors axially delimiting said gain portion thereby forming a laser resonator in said gain portion, the improvement wherein at least one of the reflectors is constituted by a Bragg grating consisting of a plurality of axially consecutive periodic perturbations in the refractive index of the optical waveguide, said Bragg grating reflecting the stimulated light with a reflectivity profile this is a maximum at a central wavelength corresponding to a central longitudinal mode of the laser resonator, said reflectivity profile decreasing for longitudinal modes adjacent to said central longitudinal mode of the laser resonator, and wherein the axial length of the laser resonator, the reflectivity of the one Bragg grating, and the gain of the excitable material are such that lasting occurs only at said central longitudinal mode of the laser resonator.

2. The improvement as defined in claim 1, wherein both of said two reflectors are constituted by said Bragg gratings.