High-speed all-optical modulation of a standard quantum cascade laser by front facet illumination

A simple experimental scheme to control intersubband lasing transition by optically induced nonresonant interband transition is presented, allowing for high-speed all-optical modulation of mid-infrared (MIR) quantum cascade laser (QCL). Illuminating the QCL front facet with 100 fs Ti:sapphire laser pulse, a fast modulation of a cw-MIR emission is observed with an estimated transient time of less than 81 ps, limited by instrument bandwidth, and a modulation depth of 18%. It has a great potential for high-speed modulation of high power QCL at room temperature.