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We demonstrate monolithic tunable terahertz quantum cascades laser sources with a tuning range over 580 GHz at room temperature by integrating electrically separated distributed feedback section and distributed Bragg reflector section into a single device.
Time-resolved far-field measurements of Quantum Cascade lasers show intra-pulse beam steering on the nanosecond scale. Spatially-dependent spectra at different pulse times show evidence of frequency locking between transverse modes when the beam steering happens. The light pulse instability has been found to reduce the device received output power by 20% in some cases. A proposal on how to reduce...
Two different ultra-strong coupling Quantum Cascade laser designs and their modified versions with two taller electron exit barriers are compared experimentally to study the influence of such taller electron exit barriers on the device performance.
Single-mode Quantum Cascade lasers employing a candy-cane shaped Fabry-Perot cavity are demonstrated. Single-mode emission with ∼25 dB side mode suppression is achieved up to ∼500 mA above threshold current in pulsed operation.
Time-resolved far-field measurements of Quantum Cascade lasers show beam steering on the few nano-second scale. Spatially resolved spectra show that the beam steering is accompanied with frequency locking between transverse modes.
We demonstrate a quantum cascade laser for detecting 12CO2 and 12CO2 isotopes for use in fingerprinting CO2 emissions from sources such as power plants and carbon storage reservoirs. The lasers emit a single mode at 4.22 μm in continuous wave operation.
We demonstrate single mode operation of Quantum Cascade lasers employing a folded Fabry-Perot resonator waveguide design. Single mode emission is achieved with ∼20dB side mode suppression up to ∼400mA above threshold current in pulsed operation.
A thermoelectric effect is observed in quantum cascade lasers and validated through thermal/electrical transport modeling. Choosing the proper polarity leads to an active core heat reduction of 9 K for a 7.5 kW/cm2 thermal load.
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 study high performing mid-infrared quantum cascade lasers with highly discretized injector regions. We observe negative differential resistance features of ~2V that persist to room temperature and pulse instabilities below 180K.
Using low-duty cycle pulses superimposed on a DC current, we determine the type of power roll-over and obtain the instantaneous threshold current, current efficiency and core temperature of a quantum-cascade laser in continuous wave operation.
Temperature-dependent optical gain and waveguide loss have been measured for continuous-wave operated quantum-cascade lasers with wavelengths between 8.2 and 10.2 mum up to room temperature using the Hakki-Paoli method. The gain coefficient decreases with increasing temperature, and is close to the designed value for vertical transition lasers, but smaller than the designed value for diagonal transition...
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