Mode-locked pulses from mid-infrared quantum cascade lasers.
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.
Wang
Christine Y
CY
Department of Physics and 2School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
Kuznetsova
Lyuba
L
Gkortsas
V M
VM
Diehl
L
L
Kärtner
F X
FX
Belkin
M A
MA
Belyanin
A
A
Li
X
X
Ham
D
D
Schneider
H
H
Grant
P
P
Song
C Y
CY
Haffouz
S
S
Wasilewski
Z R
ZR
Liu
H C
HC
Capasso
Federico
F