Abstract

There are three basic techniques of diode laser linewidth narrowing. One uses fast electronic feedback with optical reference cavity for phase noise detection^1,2 and the other two utilize pure optical feedback: strong coupling to a low-Q external cavity,^1,3 and weak coupling to a multipass external resonator.⁴ Both techniques have some advantages, and it is very attractive to combine them in a single system.⁵ The attempts and problems of realizing the stable single-mode operation of an extended cavity diode laser (ECDL) strongly coupled to a high-Q cavity are presented.

© 1994 IEEE