Relative intensity noise of a mid-infrared quantum cascade laser: insensitivity to optical feedback

This article experimentally demonstrates that the relative intensity noise (RIN) of a mid-infrared quantum cascade laser is insensitive to the optical feedback for feedback ratios up to 31% (-5.1 dB). The RIN of the free-running laser is in the range of -150 dB/Hz to -160 dB/Hz, while the optical feedback induced RIN variation is less than ± 2.0 dB. In addition, the feedback-induced lasing frequency variation is less than 2.0 GHz. Rate equation analyses of the laser are in good agreement with the experimental observations.