2D patch antenna array on a double metal quantum cascade laser with >90% coupling to a Gaussian beam and selectable facet transparency at 19 THz

=2.45) of the BCB substrate. Because the patch array has a very low input reflectivity of -13 to -20 dB over the 1.7-2.1 THz operation band, the laser needs a partially transmitting reflector to maintain the Q-factor of the active medium resonator to assure lasing in the antennas operation band. By changing the dimensions of the reflector, the facet transparency can be designed in a wide range from fully transmissive to highly reflective.