Media 1: Grating-based far field modifications of ring quantum cascade lasers

Originally published in Optics Express on 30 June 2014 (oe-22-13-15829

Far-Infrared Quantum Cascade Lasers Operating in the AlAs Phonon Reststrahlen Band

We report on the operation of a double metal waveguide far-infrared quantum cascade laser emitting at 28 μm, corresponding to the AlAs-like phonon reststrahlen band. To avoid absorption by AlAs-like optical phonons, the Al-free group V alloy GaAs_0.51Sb_0.49 is used as a barrier layer in the bound-to-continuum-based active region. Lasing occurs at a wavelength of 28.3 μm, which is the longest wavelength among the quantum cascade lasers operating from mid-infrared to far-infrared. The threshold current density at 50 K is 5.5 kA/cm², and maximum operation temperature is 175 K. We also discuss the feasibility that the operation wavelength can cover the whole spectral range bridging between mid-infrared and terahertz by choosing properly suited group III–V materials

Supplement 1: Random lasers for broadband directional emission

SupplementaryMaterial Originally published in Optica on 20 October 2016 (optica-3-10-1035

Microcavity-Integrated Graphene Photodetector

There is an increasing interest in using graphene, for optoelectronic applications.− However, because graphene is an inherently weak optical absorber (only ≈2.3% absorption), novel concepts need to be developed to increase the absorption and take full advantage of its unique optical properties. We demonstrate that by monolithically integrating graphene with a Fabry-Pérot microcavity, the optical absorption is 26-fold enhanced, reaching values >60%. We present a graphene-based microcavity photodetector with responsivity of 21 mA/W. Our approach can be applied to a variety of other graphene devices, such as electro-absorption modulators, variable optical attenuators, or light emitters, and provides a new route to graphene photonics with the potential for applications in communications, security, sensing and spectroscopy

Remote Sensing with Commutable Monolithic Laser and Detector

The ubiquitous trend toward miniaturized sensing systems demands novel concepts for compact and versatile spectroscopic tools. Conventional optical sensing setups include a light source, an analyte interaction region, and a separate external detector. We present a compact sensor providing room-temperature operation of monolithic surface-active lasers and detectors integrated on the same chip. The differentiation between emitter and detector is eliminated, which enables mutual commutation. Proof-of-principle gas measurements with a limit of detection below 400 ppm are demonstrated. This concept enables a crucial miniaturization of sensing devices