Open AccessRf-modulation of mid-infrared distributed feedback quantum cascade lasers
Author(s) -
Borislav Hinkov,
Andreas Hugi,
Mattias Beck,
Jérôme Faist
Publication year - 2016
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.003294
Subject(s) - sideband , quantum cascade laser , optics , optoelectronics , cascade , lasing threshold , materials science , laser , semiconductor laser theory , amplitude modulation , microwave , frequency modulation , physics , radio frequency , telecommunications , chemistry , chromatography , quantum mechanics , computer science
We present the electrical and optical characterization and theoretical modeling of the transient behavior of regular 4.5-μm single-mode emitting distributed feedback (DFB) quantum cascade lasers (QCLs). Low residual capacitance together with a high-frequency optimized three-terminal coplanar waveguide configuration leads to modulation frequencies up to 23.5 GHz (optical) and 26.5 GHz (electrical), respectively. A maximum 3-dB cut-off value of 6.6 GHz in a microwave rectification scheme is obtained, with a significant increase in electrical modulation bandwidth when increasing the DC-current for the entire current range of the devices. Optical measurements by means of FTIR-spectroscopy and a heterodyne beating experiment reveal the presence of a resonance peak, due to coupling of the lasing DFB- with its neighboring below-threshold Fabry-Pérot-(FP-)mode, when modulating around the cavity roundtrip frequency. This resonance is modeled by a 2-mode Maxwell-Bloch formalism. It enhances only one sideband and consequently leads to the first experimental observation of the single-sideband regime in such kind of devices.