G. Livescu

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We present a method for transparent watermarking using a custom bidirectional imaging device. The two innovative concepts of our approach are reflectance coding and multiview imaging. In reflectance coding, information is embedded in the angular space of the bidirectional reflectance distribution function (BRDF) and this information can vary at each surface(More)
Using a 6 X 6 array of integrated quantum-well self-electro-optic-effect devices, we demonstrate an optically addressed spatial light modulator able to convert a visible, incoherent image into coherent infrared (IR) light. Depending on the IR wavelength used, the output is either a positive, binary-thresholded version of the input (bistable mode) or its(More)
We have fabricated high-speed Si metal-semiconductor-metal photodetectors using(19) F(+) ion implantation in low-doped Si. Bandwidths in excess of 6 GHz have been obtained that represent more than an order-of-magnitude improvement over unimplanted counterparts. Measurements with short optical pulses show that the increase in bandwidth is due primarily to a(More)
We demonstrate that GaAs/AlGaAs smart pixels can be operated with picosecond and subpicosecond laser pulses. Switching times as short as 200 ps are measured. Our results confirm the theoretical prediction that input mode-locked pulses are more advantageous than the more typical square-wave pulses. They also suggest that use of picosecond mode-locked pulses(More)
We extend our recent general discussion of electroabsorption and refraction in multiple-quantum-well modulators to determine the optimum modulator design for smart-pixel applications. In addition to the optimum operating wavelength shift, from that of the zero-voltage exciton, we determine the optimum number of quantum wells, and we calculate the(More)
Optically bistable symmetric self-electro-optic-effect devices that use an asymmetric Fabry-Perot resonator are demonstrated and assessed. Contrast ratios exceeding 30 for low bias levels (under 6 V) are measured for low intensities. The Fabry-Perot self-electro-optic-effect device is also shown to saturate readily with intensity, with the contrast ratio(More)
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