Intersubband gain-induced dispersion.
Time-resolved transmission spectroscopy of a mid-infrared quantum cascade laser emitting at 11.7 mum allows us to iteratively retrieve the effective refractive index and the extinction coefficient of the gain medium in a broad spectral range with an accuracy of +/-7x10(-3). Besides a 3% slowdown of the group velocity we find a large induced group-velocity dispersion with changing signs in the vicinity of the gain maximum, disclosing implications for self-pulse formation in quantum-cascade lasers. Additionally we measured the temperature in the active region by exploiting the thermo-optic effect. A linear behavior with respect to the current and the duty cycle was observed.
Parz
Wolfgang
W
Institute for Photonics, Vienna University of Technology, Vienna, Austria. wolfgang.parz@tuwien.ac.at
Müller
Thomas
T
Darmo
Juraj
J
Austerer
Maximilian
M
Strasser
Gottfried
G
Wilson
Luke
L
Cockburn
John
J
Krysa
Andrey
A
Roberts
John
J
Unterrainer
Karl
K