title: Time-domain upconversion measurements of group-velocity dispersion in quantum cascade lasers.
abstract: A time-resolved mid-infrared upconversion technique based on sum-frequency generation was applied to measure pulse propagation in lambda approximately 5.0 mum quantum cascade lasers operated in continuous wave at 30 K. The wavelength-dependent propagation delay of femtosecond mid-infrared pulses was measured to determine the total group-velocity dispersion. The material and waveguide dispersion were calculated and their contributions to the total group-velocity dispersion were found to be relatively small and constant. The small-signal gain dispersion was estimated from a measurement of the electroluminescence spectrum without a laser cavity, and was found to be the largest component of the total GVD. A negative group-velocity dispersion of beta2 ( =d2beta/d omega2) approximately - 4.6x10-6 ps2/mum was observed at the peak emission wavelength, and good agreement was found for the measured and calculated pulse-broadening.
authors: Hyunyong
authors: H
authors: Choi
authors: Laurent
authors: L
authors: Diehl
authors: Federico
authors: F
authors: Capasso
authors: David
authors: D
authors: Bour
authors: Scott
authors: S
authors: Corzine
authors: Jintian
authors: J
authors: Zhu
authors: Gloria
authors: G
authors: Hofler
authors: Theodore B
authors: TB
authors: Norris