Far-infrared radiation response of antenna-coupled quantum-effect devices

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 227-238).by Rolf A. Wyss.Ph.D

Traveling-Wave Photomixers Based On Noncollinear Optical/Terahertz Phase-Matching

Traveling-wave THz photomixers based on angle-tuned optical/THz phase-matching are experimentally demonstrated. A dc-biased coplanar stripline terminated by a planar antenna is fabricated on low-temperature-grown GaAs. A distributed area between the striplines is illuminated by two noncollinear laser beams which generate interference fringes accompanied by THz waves. The velocity of the optical fringe is matched to the THz-wave velocity in the stripline by tuning the incident angle of the laser beams. The device can handle the laser power over 300 mW and provides the THz output of ~0.1 µW with the 3-dB bandwidth of 2 THz. The experimental results show that traveling-wave photomixers have the potential to surpass conventional small area designs

Design and characterization of optical-THz phase-matched traveling-wave photomixers

Design and characterization of optical-THz phase-matched traveling-wave photomixers for difference-frequency generation of THz waves are presented. A de-biased coplanar stripline fabricated on low-temperature-grown GaAs is illuminated by two non-collinear laser beams which generate moving interference fringes that are accompanied by THz waves. By tuning the offset angle between the two laser beams, the velocity of the interference fringe can be matched to the phase velocity of the THz wave in the coplanar stripline. The generated THz waves are radiated into free space by the antenna at the termination of the stripline. Enhancement of the output power was clearly observed when the phase-matching condition was satisfied. The output power spectrum has a 3-dB bandwidth of 2 THz and rolls off as ~9 dB/Oct which is determined by the frequency dependent attenuation in the stripline, while the bandwidth of conventional photomixer design has the limitation by the RC time constant due to the electrode capacitance. The device can handle the laser power of over 380 mW, which is 5 times higher than the maximum power handring capability of conventional small area devices. The results show that the traveling-wave photomixers have the potential to surpass small area designs, especially at higher frequencies over I THz, owing to their great thermal dissipation capability and capacitance-free wide bandwidth

A traveling-wave THz photomixer based on angle-tuned phase matching

A traveling-wave THz photomixer based on a free-space optical-THz phase-matching scheme is proposed. A dc-biased coplanar strip line fabricated on low-temperature-grown GaAs serves as the active area of the device, and is illuminated by two noncollinear laser beams which generate interference fringes that are accompanied by THz waves. The device with the laser-power-handling capability over 300 mW and a 3-dB bandwidth of 1.8 THz was experimentally demonstrated. The results show that traveling-wave photomixers have the potential to surpass small-area designs

Rat reproductive performance following photodynamic therapy with topically administered Photofrin

A rat animal model was used for comparing the photodynamic efficacy of two formulations of topically administered Photofrin in the uterus: 0.7 mg/kg Photofrin and 0.7 mg/kg Photofrin + 4% Azone, a penetrationenhancing agent. Uterine structure and reproductive performance were evaluated following illumination with 80 J/cm2 of 630 nm light. Fluorescence microscopy was employed to determine drug localization in frozen uterine sections at various times after drug administration. Functionality studies demonstrated a significant reduction in the number of implantations per treated uterine horn compared to controls. The mean number of implantations decreased systematically on increasing the interval between Photofrin administration and light application. At 72 h, 0.88 ± 0.52 gestational sacs per rat were recorded with Photofrin therapy, compared with 8.1 ± 1.12 (P = 0.01) on the untreated side, indicating nearly complete loss of reproductive capability. Similar results were achieved after only 3 h treatment with Photofrin + Azone (0.38 ± 0.26 sacs per rat versus 7.5 ± 1.07 on the untreated side; P = 0.01). This indicates that the effect of Photofrin can be enhanced either by extending the drug incubation period from 3 to 72 h or by adding the penetration-enhancing drug Azone. Fluorescence pharmacokinetic studies suggest that both forms of topically administered Photofrin are diffusely distributed throughout the endometrium at virtually the same rate. However, Azone may enhance the selectivity of photodynamic therapy by facilitating drug targeting to critical endometrial structure

High-Frequency (> 100 GHz) Electronic Devices

Contains reports on four research projects, the research facility and a list of publications.Defense Advanced Research Projects Agency Contract MDA972-90-C-0021National Aeronautics and Space Administration Grant NAG2-693National Science Foundation Grant ECS 91-0933

High-Frequency (> 100 GHz) Electronic Devices

Contains reports on five research projects and a list of publications.MIT Lincoln LaboratoryNational Aeronautics and Space Administration Grant NAG2-693National Science Foundation Grant ECS 91-09330Defense Advanced Research Projects Agency Contract MDA972-90-C-0021U.S. Army - Research Office Grant DAAL03-92-G-025

High-Frequency (> 100 GHz) and High-Speed (< 1 ps) Electronic Devices

Contains reports on six research projects and a list of publications.MIT Research Laboratory of Electronics Postdoctoral FellowshipNational Science Foundation Grant DMR 90-22933MIT Lincoln Laboratory Advanced Concept ProgramAdvanced Research Projects Agency Contract MDA972-90-C-0021MIT Lincoln LaboratoryNational Aeronautics and Space Administration Grant NAG2-693U.S. Army Research Office Grant DAAL03-92-G-025

High-Frequency (> 100 GHz) and High-Speed (< 10 ps) Electronic Devices

Contains an introduction, reports on four research projects and a list of publications.Defense Advanced Research Projects Agency Contract MDA972-90-C-0021National Aeronautics and Space Administration Grant NAGW-4691National Aeronautics and Space Administration Grant 959705National Science Foundation Grant AST 94-23608National Science Foundation/MRSEC Grant DMR 94-00334MIT Lincoln Laboratory Advanced Concept Program Grant BX-5464U.S. Army Research Office Grant DAAH04-95-1-0610Hertz Foundation FellowshipU.S. Army - Office of Scientific Research Grant DAAH04-94-G-016