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We temporally resolve ultrafast modulation of quantum cascade lasers (QCLs) using a near-infrared pump mid-infrared probe technique. We compare interband and intersubband transition mechanism assisted modulation of QCLs by using different pump wavelengths.
Heat dissipation issues are critical for quantum-cascade-laser (QCL) high-power operations. Simulation shows multi-emitter array can better dissipate heat than broad area laser does. QCL arrays with 5 and 16 elements are fabricated and results are presented.
Using quantum-cascade-lasers (QCL) as resonant optical amplifiers, active filters, and detectors with gain, we demonstrated signal amplification in the mid-IR wavelength range. Optical gain of >10dB and electrical gain of >28dB were achieved.
Neuron optical excitations are important for brain-circuitry explorations and sensory-neuron-stimulation applications. To optimize the stimulation, we identify neuron mid-IR absorption peaks in this study and discuss their meanings and delivery methods of mid-IR photons.
We report a tunable mid-infrared photo-detector based on quantum cascade laser (QCL). The device is biased below and near threshold and it performs as a resonant optical amplifier and at the same time a photo-detector.
Standoff photoacoustic chemical detection using quantum cascade lasers is demonstrated. With 40 mW power the detection distance is extended from 1–2 inches to, currently, 17 feet through component and acoustic coupling improvement.
Standoff chemical detection using quantum-cascade-lasers as pump sources and photoacoustic techniques for sensing is demonstrated for the first time. With <40mW laser power, a chemical detection distance of more than one meter has been achieved.
Leakage current in quantum-cascade-lasers with oxide-blocked-ridge waveguide and buried-heterostructure (with/without n-InP top-cover) are compared using electrical derivative measurements. Oxide-blocking structure provides the least leakage current although the top-covered BH QCLs show the toughest durability.
Growth quality of quantum-cascade-lasers (QCLs) is difficult to be characterized due to the demanding requirements on hetero-interface quality and thickness control for all >1000 nano-scale superlattice structure. In this work we employ X-ray diffractometry (XRD) to effectively evaluate QCL-wafer growths.
Testing QCL devices usually requires cryogenic systems, mid-IR windows, optics and detectors. We report here the demonstration of an electrical derivative method that can quickly measure QCL lasing thresholds without using mid-IR optics or detectors.
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