Laser relaxation-oscillation frequency imaging

We describe a new imaging technique based on modification of laser relaxation frequency induced by coherent optical feedback from an external target. A direct comparison (both theoretical and experimental) is made with laser feedback interferometry techniques, in which there is a modification of the laser's steady state. We show that, for a laser with a cavity damping rate gamma(c) higher than the population damping rate, gamma(1) , the modification of the laser relaxation frequency can be several orders of magnitude more sensitive than the perturbation of the laser's output power. Application of this technique to imaging is reported.