3 research outputs found
Enhancing the photomixing efficiency of optoelectronic devices in the terahertz regime
A method to reduce the transit time of majority of carriers in photomixers
and photo detectors to ps is proposed. Enhanced optical fields associated
with surface plasmon polaritons, coupled with velocity overshoot phenomenon
results in net decrease of transit time of carriers. As an example, model
calculations demonstrating (or 2800 and 31.8 W at 1
and 5 THz respectively) improvement in THz power generation efficiency of a
photomixer based on Low Temperature grown GaAs are presented. Due to minimal
dependence on the carrier recombination time, it is anticipated that the
proposed method paves the way for enhancing the speed and efficiency of
photomixers and detectors covering UV to far infrared communications
wavelengths (300 to 1600 nm).Comment: 5 pages, 4 figure
Orientational Glasses: NMR and Electric Susceptibility Studies
We review the results of a wide range of nuclear magnetic resonance (NMR)measurements of the local order parameters and the molecular dynamics of solid ortho-para hydrogen mixtures and solid nitrogen-argon mixtures that form novel molecular orientational glass states at low temperatures. From the NMR measurements, the distribution of the order parameters can be deduced and, in terms of simple models, used to analyze the thermodynamic measurements of the heat capacities of these systems. In addition, studies of the dielectric susceptibilities of the nitrogen-argon mixtures are reviewed in terms of replica symmetry breaking analogous to that observed for spin glass states. It is shown that this wide set of experimental results is consistent with orientation or quadrupolar glass ordering of the orientational degrees of freedom