Showing papers by "Gang Chen published in 2009"

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

Abstract: 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.

Quantum cascade laser gain enhancement by front facet illumination

Abstract: Optical gain enhancement is demonstrated in a standard mid-infrared quantum cascade laser in pulse operation, using a near infrared illumination on the laser facet. An increase in the laser emission is observed, as well as greater dynamic range, threshold reduction, and a blue shift in the laser cavity modes. The optically induced gain increase allows for optical switching of the laser. All the changes have a nonlinear dependency on the illumination optical power and are attributed to the free carrier concentration increase and the electron transport change in the active region due to the near infrared illumination.

All-optical amplitude modulation of a middle-infrared quantum cascade laser

Abstract: We demonstrated the all-optical modulation in the optical emission power of a standard middle infrared quantum cascade laser by optically illuminating its front facet with femtosecond near infrared pulse train The modulation frequency is found up to 1035 GHz, much faster than the observed laser current response, only 3 GHz