Intracavity amplitude modulation of quantum-cascade lasers using intersubband absorption in the active region under reverse bias

Abstract

We have analyzed light absorption in a quantum cascade laser structure under forward and reverse bias. Strong absorption modulation at the laser frequency is predicted and observed experimentally for the voltage variation within the high differential resistance voltage range. We propose to use this mechanism for monolithically integrated intracavity modulation of quantum cascade lasers, promising suppressed thermal chirp and fast modulation capability. In addition, the described method allows for extraction of the intersubband absorption from the total waveguide losses.