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A mode-locking mechanism by active gain modulation is studied numerically and experimentally. The parameter window for the emission of stable pulse trains was found. Pulses as short as 3 ps (~0.5 pJ) were characterized by second-order autocorrelation.
A quantum-cascade laser design for suppressing carrier leakage from the active region was achieved. For both threshold and slope efficiency the characteristic temperatures, T0 and T1, reach values of 238 K over the 20-60degC range.
A density-matrix based theory of transport and lasing in quantum-cascade lasers reveals that large disparity between lasing linewidth and tunneling broadening changes the design guidelines to favor strong coupling between injector and upper laser level.
A 65-nm quasi-continuous tuning range is reported for a 3.5-mm-wide optically pumped type-II chirped-grating distributed-feedback laser at 3.2 mum. Methane absorption spectra demonstrate the utility of this source for atmospheric-pressure molecular spectroscopy.
We calculate intersubband absorption loss and report measured waveguide loss for two high-performance mid-infrared quantum cascade laser designs. Intersubband absorption loss accounts for a major component of waveguide loss for these structures.
We demonstrate a Quantum Cascade Laser employing ultra-strong (~20 meV) coupling between the injector and the upper laser state. The laser shows a pulsed wall-plug efficiency of 34%(8%) and peak power of 8.0 W(2.0 W) at 80 K(300 K).
We report operation of v ~ 2.7 THz quantum-cascade lasers (QCLs) up to 174 K. A new three-well active region, one-well injector scheme is utilized to lower the operating current densities. While the temperature performance of this design is comparable to that of the best published THz QCLs, lower operating current densities make this design a viable alternative.
We demonstrate Limaccedilon-shaped microcavity lambda=10 mum lasers with directional emission. Their performance is robust with respect to variations of the deformation factor near its optimum value epsiv=0.40. Excellent agreement between experiments and theory is achieved.
An injectorless quantum cascade laser design, using two 0.6 nm InAs spikes within the active zone, yielding shorter wavelength and improved performance is presented. The average pulsed output power was measured to 880 mW at 297 K.
We demonstrate a tunable terahertz quantum cascade laser using an abutted silicon lens and grating feedback. The device tunes discontinuously over 160 GHz with a center frequency of 4.4 THz.
Rapidly responding, high-sensitivity terahertz (THz)-wave detection with an organic DAST crystal was demonstrated using nonlinear frequency up-conversion to near-infrared light. Detection of THz-wave signals from 16.4-THz to 26.3-THz was achieved at room temperature.
We demonstrate magnetic field assisted, (sub)THz quantum cascade laser operating above 200 K. This is achieved through the application of strong magnetic fields which provide an additional lateral confinement in order to suppress non-radiative intersubband scattering.
Production of intense infrared pulses with 250-muJ pulse energy from a laser wakefield accelerator is demonstrated. It is strongly correlated with the production of self-injected monoenergetic electron beam.
Improvements in the design of mid-infrared interband cascade lasers have allowed them to operate cw to 334 and 319 K for devices with emission wavelengths of 3.3 and 3.7 mum, respectively.
We report the first room temperature strain compensated InGaAs/AlAs(Sb)/InP quantum cascade lasers operating down to 3.15 mum. The lasers with selective incorporation of AlAs barriers in the active regions emit hundreds of milliwatts peak optical power.
We demonstrate a quantum cascade laser featuring a low-voltage-defect short injector. Devices showing a voltage-defect as low as 20 meV and voltage efficiency of 88% at 80 K are reported, with > 80% voltage efficiency at room temperature.
A 3-mm-long, 150-mum-wide broad-area quantum cascade laser (lambda = 4.65 mum) with sidewall corrugations produced a maximum-current-limited pulsed output power of 53 W and wall-plug efficiency of 29.4% from two facets at 80 K. The processing was applied to a structure which employed a Ga0.33In0.67As/Al0.64In0.36As strain-compensated double-phonon design with the injection barrier thinned in order...
A new Quantum Cascade laser design with a ldquotwo-steprdquo coupling between the injector and the active region provides a voltage tuning range of 200 cm-1 for electroluminescence and 80 cm-1 for laser spectra at room temperature.
Electroluminescence from GaInSb/AlGaInSb quantum well (QW) diode lasers, grown on GaAs, has been investigated as a function of strain in the QWs, with lasing occurring at ~3.3 mum at 200 K with 1.1% strain in the QW.
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