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Now showing items 61-70 of 72
Planar THz quasioptics
(AIP Publishing, 2004-08-09)
Two-dimensional (2D) quasioptical elements are demonstrated as guiding structures in the THz frequency regime. A planar polyethylene lens is incorporated in a parallel metal plate structure and is shown to focus guided THz ...
Optical pulse compression based on enhanced frequency chirping
(AIP Publishing, 1982-07-01)
Through numerical simulations, we show that, under relatively general conditions, passage of an intense picosecond pulse through a single-mode optical fiber can cause the pulse to become strongly frequency broadened with ...
Line-shape transition of collision broadened lines
(American Physical Society, 1995-02-20)
Using the newly developed technique of THz time-domain spectroscopy, we have measured the far-wing absorption line profile of the ensemble of collision broadened ground state rotational lines of methylchloride vapor out ...
Optical pulse compression
(AIP Publishing, 1974-11-15)
Dramatic and controllable reshaping of frequency-modulated dye laser pulses has been observed. The pulses, nearly resonant with the 2P1/2 line (7948 A) of Rb, first passed through a LiNbO3 frequency modulator, and then ...
Coherent excitation, incoherent excitation, and adiabatic states
(American Physical Society, 1976-08)
Coherent excitation of an atomic excited state occurs during the propagation of near-resonant light pulses and is responsible for the induced polarization. Simultaneously, incoherent excitation occurs due to the relaxation ...
Observation of self-steepening of optical pulses with possible shock formation
(American Physical Society, 1973-08-13)
Near-resonant light pulses were steepened by passage through Rb vapor. The rise time changed from typically 4 nsec to less than 1 nsec, and complicated envelopes developed. The self-steepening, well described by adiabatic ...
Trap-enhanced electric fields in semi-insulators: The role of electrical and optical carrier injection
(AIP Publishing, 1991-10-14)
We report extremely large field enhancement near the anode of an electrically biased metal/semi-insulator/metal structure. The large anode field results from a trap-enhanced space-charge region and is large enough to cause ...
Terahertz two-cylinder waveguide coupler for transverse-magnetic and transverse-electric mode operation
(AIP Publishing, 2011-02-18)
We report the coupling and guiding of broadband terahertz radiation using a two-cylinder waveguide coupler. For the transverse electromagnetic TEM (TM0) geometry, the two opposing metal cylinders exhibit an amplitude ...
Measurement of ultrafast hot-carrier relaxation in silicon by thin-film-enhanced, time-resolved reflectivity
(AIP Publishing, 1988-01-04)
Time-resolved reflectivity measurements within ~100 fs resolution have revealed an initial 350 fs relaxation time in silicon, believed to be the time it takes hot, photoinjected carriers to relax to the band edge. The ...
High Q, one-dimensional terahertz photonic waveguides
(AIP Publishing, 2007-02-28)
A one-dimensional (1D) photonic metal parallel plate waveguide is presented in the spectral range of 0.5-3 THz that has high throughput and stop bands with up to the experimental limit of 40 dB of dynamic range. By ...