A birefringent etalon as single-mode selector in a laser cavity

A novel technique is demonstrated for stabilizing an intra-cavity etalon used for single-mode selection in a laser cavity. By appropriate polarization analysis of the reflection from an etalon designed as a quarterwave plate an electronic signal can be derived, that enables the implementation of an electronic stabilization scheme. This scheme obviates the need for any modulation of the etalon in order to ensure stable single mode operation of a cw tunable laser.