Excess frequency noise in interband cascade lasers: towards narrower-linewidth operation

Interband Cascade Lasers are becoming more and more attractive sources for sensing applications due to their direct mid-IR emission and low power consumption. In many demanding applications of precision spectroscopy and imaging, the laser frequency and intensity noise represent the ultimate limiting factor for the final sensitivity. Here, we first characterize the response of a DFB ICL to a frequency modulation and measure its tuning coefficients. A frequency noise analysis of the ICL is then provided, through experimental investigation of the frequency noise power spectral density, with a particular attention to the technical noise contribution. A possible scheme for frequency stabilization and linewidth narrowing is presented through frequency locking to a high-Q factor microresonator.