Michael Wraback

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We present optically tunable metamaterials (MMs) on flexible polymer sheets operating at terahertz (THz) frequencies. The flexible MMs, consisting of electric split-ring resonators (eSRRs) on patterned GaAs patches, were fabricated on a thin polyimide layer using a transfer technique. Optical excitation of the GaAs patches modifies the metamaterial(More)
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Related Articles Near-field dynamics of broad area diode laser at very high pump levels AIP Advances 1, 042148 (2011) Photonic bandstructure engineering of THz quantum-cascade lasers Appl. Phys. Lett. 99, 201103 (2011) Simulation of quantum cascade lasers J. Appl. Phys. 110, 093109 (2011) Ultra-broadband heterogeneous quantum cascade laser emitting from 2.2(More)
A sinusoidal dependence of the sand p-polarized terahertz (THz) emission on sample rotation angle in mand a-plane InN has been observed using ultrafast pulse excitation at a moderate pump fluence of 1 J/cm. The angular dependence is attributed to carrier drift in an intrinsic in-plane electric field parallel to the c-axis induced by stacking(More)
We report a novel approach to the design of normal incidence multiple quantum well light modulators. The quantum confined Stark effect is utilized to tune the light polarization rotation and phase retardation created by a thermally induced in-plane anisotropic strain. An exceedingly high contrast ratio of 5000:1 is demonstrated for a normally-on device at(More)
III-Nitride based deep ultraviolet (DUV) light emitting diodes (LEDs) offer smaller size, wider choice of peak emission wavelengths, lower power consumption and reduced cost compared to mercury vapor lamps and other UV light sources. Increasing efficiency of DUV LEDs accelerates their applications in bio-agent detection, analytical instrumentation,(More)
III-Nitride/SIC separate absorption and multiplication avalanche photodiodes (SAM APDs) provide a new approach for realizing high sensitivity, high gain and low dark current detectors with a response that is tunable over a wide spectral range. However, the heterojunction interface plays a significant role in the performance of these detectors due to(More)