Abstract

The frequency modulated continuous wave (FMCW) technique¹, which was developed and used in radar systems, has recently been applied to optical sources in interferometric sensors. Applications of this technique include remote distance sensing², fiber evaluation¹, and characterization of the source itself. The use of single frequency lasers is especially attractive because the optical frequency can be directly modulated over a large range by injection current modulation. The resolution of such systems³ often suffers from intensity modulation accompanying the frequency modulation. The range of measured distances is limited by the short coherence length of semiconductor lasers. These problems have been alleviated in the present work by using two-section constant amplitude tunable lasers and external cavities for linewidth narrowing.

© 1988 Optical Society of America