Integrated quantum cascade laser-modulator using vertically coupled cavities

We demonstrated an integrated three terminal device able to modulate the cavity losses of quantum cascade lasers. By growing asymmetric doped quantum wells coupled to the laser's mode an absorption peak can be electrically shifted in and out the laser transition. The use of three terminals allows one to drive the laser independently from the wells and therefore to modulate the laser's amplitude with an electrical power of only a few milliwatts. This is far less than the power needed for a direct modulation of the laser light.