Abstract
New insights into the laser dynamics of interband cascade lasers reveal the possibility to generate frequency-modulated combs by utilizing their inherent gain nonlinearity. The resulting comb state is characterized by chirped instantaneous frequency, which appears to be universal to frequency combs based on gain-induced four-wave mixing. The fast dynamics in the injectors further allow the realization of exceptionally sensitive and high-speed photodetectors, operating at room temperature, using the very same epilayer structure. With the capability of integrating frequency combs and ultra-fast detectors on a single chip consuming less than a watt of electric power, interband cascade laser technology provides a complete and unmatched platform for future monolithic and battery-driven dual-comb spectrometers.
Highlights
Sensors are the heart of every smart technology
The mid-infrared region is the spectral region of choice when it comes to sensing and spectroscopy
Our findings and conclusions on frequency comb operation are different from those of recent works that focused on comb generation via passive mode-locking of interband cascade lasers (ICLs) [21] and suggest that a careful reinterpretation of those results is required. (Recent results on passive mode-locking of ICLs [23] include both a second-order autocorrelation as well as a multiheterodyne beat trace, which show no sign of pulse formation, lacking the 8:1 ratio in the autocorrelation and pulses in the multi-heterodyne beat trace.) The ICL frequency combs presented in this letter rely on the inherent gain nonlinearity caused by the fast-gain dynamics
Summary
Sensors are the heart of every smart technology. They allow us to capture data about environmental pollution, plant infections, or our current physiological condition. (Recent results on passive mode-locking of ICLs [23] include both a second-order autocorrelation as well as a multiheterodyne beat trace, which show no sign of pulse formation, lacking the 8:1 ratio in the autocorrelation and pulses in the multi-heterodyne beat trace.) The ICL frequency combs presented in this letter rely on the inherent gain nonlinearity caused by the fast-gain dynamics. They do not require a saturable absorber, and show they the same phase characteristics as QCL frequency combs
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