Envelope narrowing from photorefractive phase conjugate feedback toa semiconductor laser

摘要

The effects of envelope narrowing were confirmed experimentally.nIn our experiments a Hitachi HLP1400 laser diode is coupled to a ringnPPCM that is constrained to be unidirectional. The photorefractivenmaterial used is barium titanate. The laser spectrum was compared tonthat of a laser diode coupled to an external cavity with a dielectricnmirror, i.e., we compared the effects of phase conjugate feedback tonconventional feedback. In both cases the laser is multimode when couplednto the external cavity. The envelope for the phase conjugate feedback isnnarrower than that for the conventional case. It can also be seen thatnin the conventional case the gains for the different longitudinal modesnvary with the phase delay as each mode experiences a different roundntrip phase delay. This is not the case for the phase conjugate cavitynbecause all of the modes experience the same round trip phasendelay