Experimental investigation of high-frequency noise and optical feedback effects using a 9.7 (mu)m continuous-wave distributed-feedback quantum-cascade laser

摘要

An experimental investigation of high-frequency noise, i.e., up to 3 GHz, exhibited by a 9.7 (mu)m quantum cascade laser, is described. Noise characteristics and measurements of a liquid-nitrogen-cooled continuous-wave distributed-feedback laser are presented. Well defined sets of narrow and intense resonance peaks have been observed in the 10-300 MHz range. Measurements of relative intensity noise have been performed. It is also shown that quantum-cascade lasers are sensitive to optical feedback. The excess noise generated by the feedback has been investigated under well defined conditions. A description of the experimental phenomenon is presented along with methods of minimizing optical feedback.