INJECTION LOCKING SEMICONDUCTOR-LASERS WITH PHASE-CONJUGATE FEEDBACK

Phase conjugate injection locking is shown to couple coherently two se miconductor lasers through a double phase conjugate mirror geometry. T he mutual coherence and stability of the lock band are characterized f rom the visibility and relative intensity noise measurements for vario us levels of phase conjugate coupling and frequency detunings. Side mo de phase conjugate injection locking is demonstrated by high mutual co herence with visibility approximately 0.93 and detunings up to nine lo ngitudinal mode spacings at injection levels of -22 dB. Central mode p hase conjugate injection locking with high mutual coherence is also po ssible for feedback levels of -36 dB and exhibiting an asymmetric stab le locking region of 350 MHz bandwidth within the locking band. The ph ase locking is unstable though, the reasons for which are discussed. I ncreased phase conjugate feedback extends the lock band to greater det unings and asymmetry as in direct injection locking with only a small region showing high mutual coherence. Intensity noise measurements are also discussed.