Frequency Noise Characterization of Interband Cascade Lasers

Thanks to their compactness and low-power consumption, Interband Cascade Lasers (ICLs) are emerging sources for mid-infrared (MIR) molecular sensing below 6 mu m. Understanding their noise features is of fundamental importance for applications like high-sensitivity and high-resolution spectroscopy. It could unveil details of their intrinsic physical behavior and, similarly to what happened for Quantum Cascade Lasers (QCLs), lead to the development of frequency and phase stabilization techniques for linewidth reduction. In this manuscript, we discuss the importance of full frequency noise characterization for ICLs, pointing out the main similarities and differences with respect to QCLs, and we show preliminary noise measurements. The frequency noise spectrum is analyzed and discussed, and the laser linewidth over different timescales calculated.