Thermal dependence and power-law scaling of relative intensity noise in a few-stage distributed feedback quantum cascade laser

We report the experimental characterization of the Relative Intensity Noise (RIN) in a 9-stage quantum cascade laser (QCL), revealing a pronounced power-law behavior with unusually high scaling exponents. By analyzing the RIN as a function of optical power, temperature, and modulation frequency, we extract power-law exponents reaching values significantly larger than those typically observed in conventional QCLs or interband laser diodes. This deviation highlights the dominant role of spontaneous-emission noise in few-period structures and demonstrates that reducing the number of cascade stages fundamentally alters QCL noise dynamics. The evolution of the exponent with frequency and temperature provides new insight into transport- and scattering-driven noise processes, offering a foundation for engineering low-noise mid-infrared emitters.