title: Mode-locked pulses from mid-infrared quantum cascade lasers.
abstract: In this study, we report the unequivocal demonstration of midinfrared mode-locked pulses from quantum cascade lasers. The train of short pulses was generated by actively modulating the current and hence the gain of an edge-emitting quantum cascade laser (QCL). Pulses with duration of about 3 ps at full-width-at-half-maxima and energy of 0.5 pJ were characterized using a second-order interferometric autocorrelation technique based on a nonlinear quantum well infrared photodetector. The mode-locking dynamics in the QCLs was modeled based on the Maxwell-Bloch equations in an open two-level system. Our model reproduces the overall shape of the measured autocorrelation traces and predicts that the short pulses are accompanied by substantial wings as a result of strong spatial hole burning. The range of parameters where short mode-locked pulses can be formed is found.
authors: Department of Physics and 2School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
authors: Christine Y
authors: CY
authors: Wang
authors: Lyuba
authors: L
authors: Kuznetsova
authors: V M
authors: VM
authors: Gkortsas
authors: L
authors: L
authors: Diehl
authors: F X
authors: FX
authors: Kärtner
authors: M A
authors: MA
authors: Belkin
authors: A
authors: A
authors: Belyanin
authors: X
authors: X
authors: Li
authors: D
authors: D
authors: Ham
authors: H
authors: H
authors: Schneider
authors: P
authors: P
authors: Grant
authors: C Y
authors: CY
authors: Song
authors: S
authors: S
authors: Haffouz
authors: Z R
authors: ZR
authors: Wasilewski
authors: H C
authors: HC
authors: Liu
authors: Federico
authors: F
authors: Capasso