Frequency stabilization, line narrowing and modulation studies in quantum cascade lasers

Summary form only given. Some of the applications of stabilized laser sources (mid-IR sub-Doppler spectroscopy, precision laser ranging) require reduction of the high frequency spectral noise components, resulting in fine narrowing and an increase in the coherence length of the laser. In order to achieve this, considerable servo bandwidth is required. For this reason, the phase transfer function behavior of the laser stabilization system is crucial, time delays and inductive effects being detrimental. In this paper, we report on our latest developments in QC laser stabilization, including some elegant electronics that have alleviated a number of common control theory issues including resonances and variability in the transfer function.