Variable Transmission Output Coupler And Deviationless Tuner For Tunable Lasers

Abstract

A variable transmission output coupler and deviationless tuner forms a part of a tunable laser cavity. The device uses frustrated total internal reflection to provide variable output coupling and laser tunability simultaneously. Two Pellin-Broca prisms are pressed against each other by a variable spring pressure mechanism. An adjustable screw regulates the variable force, controlling the thickness of an air film between two prism faces. The Pellin-Broca prisms enable tuning the laser without angular deviation of the output beam. All beams enter and exit at Brewster's Angle, minimizing losses. No coatings are used on the optical elements, reducing the possibility of damage at high operating power of the laser. The coupler may be used in pulsed as well as continuous wave lasers.