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We demonstrate the first II–VI based short-wave (λ ≤ 4 µm) Quantum Cascade Detector. Peak responsivity and background limited detectivity of 0.1 mA/W and 2.5×1010 cm√Hz/W, respectively, were measured at 80 K.
We present a fully integrated mid-infrared sensor. The laser and detector are fabricated from a bi-functional quantum cascade structure, connected through a dielectric-loaded surface plasmon waveguide, which acts as interaction zone and provides high coupling.
Broadly tunable single-mode quantum cascade laser at ∼10 µm with a monolithically integrated two-section slot structure is presented. The device shows ∼80 cm−1 tuning range and ∼20 dB side mode suppression ratio by adjusting the currents and temperature.
By combining first and second order DFB gratings, a new solution for surface emission QCL is presented. A QWS mode and a buried hetero-structure process allow single mode emission and low dissipation devices.
The non-uniform electric field in the active regions of an interband cascade laser is directly imaged and characterized for the first time by employing a nanoscopic voltage profiling technique.
This paper studies relation between high-frequency chirping of a quantum-cascade laser and the curvature of its light-current characteristic. Assuming negligible thermal backfilling and a photon lifetime of 9ps, a gain-compression effect explains both experimental observations.
For the first time, we present direct experimental evidence of the presence of spatial hole burning within switchable aperiodic DFB terahertz quantum cascade lasers. This will lead towards the development of quasicontinuous tuneable terahertz lasers.
Label free mid-infrared photothermal imaging on bird brain slices is presented. The Amide-I vibrational band is excited by a quantum cascade laser and an Er:doped fiber measures the photothermal response.
A dual-modulation Faraday rotation spectrometer is employed for isotopic ratiometry of nitric oxide (NO) converted from nitrate/nitrite. Excellent linearity of measured NO to dissolved nitrate is demonstrated. Ratiometry of IAEA-NO-3 standards indicates ∼3 % accuracy.
Phase locking, via resonant leaky-wave coupling, of five 8.36 µm-emitting quantum cascade lasers has provided in-phase-mode operation to 3 W with 1.5 × diffraction limit lobe-width and 2.45 W emitted in the main far-field lobe.
A wide-bandwidth, highly efficient method of inter-chip waveguide coupling suitable for on-chip, mid-infrared sensing is discussed. Simulations and preliminary fabrication work on laser-to-waveguide coupling are presented, with losses predicted to be better than 6 dB.
We propose and study GaAs/Al25Ga75As terahertz frequency quantum cascade lasers in which mid-infrared radiation is used as a coherent drive for enhancing the terahertz gain.
We consider SESAM soliton-modelocking via cascaded quadratic nonlinearities in the normal dispersion regime. We explain the theory, perform a design study for our experimental implementation in LiB3O5/Yb:CaGdAlO4, and present detailed numerical simulations of this laser.
An active spectrometer has been developed based on diffuse backscattering by solid targets combined with coherent detection and mid-infrared quantum cascade lasers. High selectivity and sensitivity have been shown at standoff distances of 40 m.
We report continuous mode-hop free tuning of a sample-grating distributed Bragg reflector (SG-DBR) quantum cascade laser (QCL) operating at 4.55µm wavelength observing N2O features in this range by controlling all three sections of laser namely: front DBR, back DBR and the phase.
Difference frequency generation in monolithic semiconductor waveguides using χ(2) nonlinearities produced mid IR radiation between 7700 – 8300 nm in a single waveguide element via 20 nm tuning of a 1550 nm fiber laser pump.
We demonstrate terahertz quantum cascade lasers based on arrays of subwavelength micropillar structures, corresponding to scaled-down photonic crystals. Stimulated emission is measured at 4 THz for devices operating in the effective medium regime of the photonic bands.
Flicker noise was studied in a set of 20 QCLs at 7–8 µm, showing significant differences among the devices and the probable existence of various noise sources. Ridgewaveguide lasers showed lower noise than buried-heterostructures.
We report high power (>3 mW) mid-infrared superluminescent emission around 2100 cm−1 from Quantum Cascade devices. The superluminescent emission shows a Gaussian shape spectrum with FWHM of 80 cm−1.
The localization of electron wavefunctions due to interface roughness in a quantum cascade heterostructures is investigated by observing the electroluminescence spectra. Localization is more prominent in heterostructures with designed extended states.
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