<title>Laser diode phase-conjugate interferometry with a frequency-modulated continuous-wave technique</title>

Abstract

Laser-diode phase-conjugate interferometry with self-pumped phase-conjugate mirrors (SPPCMs) is presented by using a frequency-modulated continuous-wave (FMCW) technique. The phase is shifted to produce a spatially uniform phase change uncancelled by a phase conjugator between two beams of an unbalanced interferometer. The phase-modulated conjugate wave with the frequency-ramped laser diode (LD) is stable since the frequency-modulated LD can decrease the grating contrast due to the average action of moving gratings inside a crystal. A wavefront-matched interferometer has been constructed with two BaTiO3, SPPCMs instead of usual two mirrors. The wavefront-matched unbalanced interferometer does not depend on the distortion of input wave, but can only detect the spatially uniform phase change introduced by the displacement of one cat mirror in two phase-conjugate mirrors. The FMCW technique can be applied to a tunable-LD wavefront-matched interferometer for distance measurement that is not significantly dependent on the phase distortion. The distance introduced by the displacement of one cat mirror in the interferometer can be measured by detecting the carrier beat frequencies with an rf spectrum analyzer.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.