Coherent near-infrared wavelength conversion in semiconductor quantum cascade lasers

A scheme for generating coherent "sidebands" on a near-infrared optical carrier beam is demonstrated experimentally, using a modified quantum cascade laser. The active region of the laser simultaneously provides the gain, generates one of the optical fields, and provides a doubly resonant second-order nonlinear optical medium. This allows coherent sideband generation with normal incidence coupling and with interaction lengths sufficiently short to be immune to phase-matching problems. The resulting electrically modulatable two-terminal device offers a means of performing various all-optical routing, switching, and detection operations of interest for optical telecommunications.