A novel velocity-matched distributed photodetector (VMDP) is proposed to simultaneously achieve high saturation photocurrent and broad bandwidth. Theoretical analysis on the tradeoff between saturation power and bandwidth shows that the VMDP offers fundamental advantages over conventional photodetectors. A comprehensive theoretical model has been developed for the design and simulation of the V...

We have combined hyperspectral imaging with spectral domain optical coherence tomography (SDOCT) to noninvasively image changes in hemoglobin saturation, blood flow, microvessel morphology, and sheer rate on the vessel wall with tumor growth. Changes in these hemodynamic variables were measured over 24 h in dorsal skin fold window chamber tumors. There was a strong correlation between volumetri...

The saturation properties of terahertz emission from biased, large-aperture photoconductors excited by trains of amplified femtosecond optical pulses are presented. A direct comparison is made of the multiple-pulse saturation properties of terahertz emission from semi-insulating GaAs and low-temperature-grown GaAs emitters with different carrier lifetimes. When the carrier lifetime is less than...

We investigate current saturation at short channel lengths in graphene field-effect transistors (GFETs). Saturation is necessary to achieve low-output conductance required for device power gain. Dual-channel pulsed current-voltage measurements are performed to eliminate the significant effects of trapped charge in the gate dielectric, a problem common to all oxide-based dielectric films on grap...

the simultaneous flow of oil and water in porous media is described by relative permeability curves, mainly derived from laboratory experiments. relative permeability is of paramount importance in predicting reservoir production performance and drive mechanisms and its value depends largely on the volume fraction of fluids present in the test samples. nowadays x-ray scanners are one of the most...

Experimental demonstration of low power laser induced optical nonlinearities in two different types of specially designed materials: dye doped liquid crystals and copolymers with new pendant azobenzene moieties, is presented. Saturation of the nonlinear refractive index change is observed for some of the samples. The origin of the huge nonlinearity and its saturation in the continuous wave lase...

We develop a statistical model to study all the relevant phenomena that can give rise to an anomalous intensity saturation in the propagation of incoherent pulses in a laser amplifier. The interplay among diffraction, self-focusing, group-velocity dispersion, gain narrowing, and gain saturation is investigated. Changes in the temporal and spatial characteristics of the pulses are shown. © 1998 ...

In this paper, effectiveness of semiconductor optical amplifiers (SOA's) in tree-net in terms of increase in the number of users has been investigated. In the analysis, SOA's with i) unsaturated gain, ii) average gain saturation, and iii) average gain saturation with gain fluctuations have been considered. Further, the results for the tree-net are compared with those for the star network. It is...

Photonic receivers integrating unitravelling carrier (UTC) photodiodes with high saturation power=high gain semiconductor optical amplifiers (SOAs) are presented. The SOAs demonstrated up to 28 dB of gain with saturation output powers of up to 18.6 dBm, while the UTC photodiodes were capable of 40 Gbit=s operation under high photocurrent operation. The chip-coupled receiver sensitivity was bett...

2014 The spin-lattice relaxation of the Fe3+ ion in cubic ZnS has been studied between 1.3 and 300 K by pulse saturation, progressive saturation and broadening of the E.P.R. line. In ZnS, the Fe3+ ion is more strongly coupled to the lattice than the isoelectronic ion Mn2+. For T > 50 K, the optical phonons contribute to the relaxation, and are responsible for a strong line broadening at 30...