Rf-modulation of mid-infrared distributed feedback quantum cascade lasers

Optics Express
Borislav HinkovJérôme Faist

Abstract

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.

References

Apr 22, 1994·Science·J FaistA Y Cho
Dec 14, 2012·Nature·Andreas HugiJérôme Faist
Oct 14, 2014·Nature Communications·Gustavo VillaresJérôme Faist
Apr 4, 2015·Optics Express·Gustavo Villares, Jérôme Faist
Jul 21, 2015·Optics Express·Stefan KalchmairMarko Loncar

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