The onset of coherence collapse in DBR lasers

A study of the dependence of the onset of coherence collapse on laser output power is discussed. Three-section multiquantum-well-distributed-Bragg-reflector (MQW-DBR) lasers were used. The fraction of light reflected back into the lasing mode was varied, and the point at which the transition to coherence collapse occurred was measured. This feedback level varies approximately linearly with laser output power. For these lasers, when the output power is 1 mW, the transition to coherence collapse begins when the optical feedback into the lasing mode is below -40 dBm; when the feedback power is -35 dBm, the laser line is completely collapsed.<>