Abstract

Two-wave mixing in a nonlinear medium can induce coherent energy transfer (GET) between a probe field and a pump^1-4 that can be strong enough to significantly affect both the probe and the pump (e.g., giving gain in absorptive media or loss in an amplifier). We use mode competition in a semiconductor laser as a sensitive test for coherent depletion of the lasing field by a weak injected probe. With injection locking, the injected field becomes the dominant competitor for optical gain, gain is suppressed for all modes, and the laser switches to the injected frequency. However, we find that below the injection-locking threshold, depletion of the strongly lasing field by a probe causes the laser to switch to a third mode, a next-best competitor that is different in polarization and frequency from both the original lasing pump mode and the injected probe field. The probe only acts to deplete the pump field and does not significantly change the material gain.

© 1995 Optical Society of America