Modulated infrared laser with two coupled cavities

Claim 1

A gas laser comprising: a main resonant cavity including a gain cell positioned along an optical axis, a source of excitation coupled to said cell, a pair of windows at opposite ends of said gain cell providing an output of vertically polarized optical energy; a coupled cavity axially aligned with said main cavity and including a polarization coupler angularly disposed at its Brewster angle to said axis for coupling energy out of said laser having a polarization normal to that from said gain cell, an electro-optic modulator spaced from said coupler in said coupled cavity along said axis for controlling the polarization of energy passing therethrough, a source of control voltage coupled to said modulator; and a plurality of mirrors including first and second highly reflective end mirrors positioned at the respective opposite ends of said main and coupled cavities and a third low reflectivity mirror positioned between said cavities, the reflection of energy between said coupled cavity end mirror and third mirror being of a phase to reinforce output of said gain cell in order to sustain continuous wave operation.