We report the first systematic study of the frequency dependence of optical nonlinearities of bulk GaAs at room temperature. In contrast to the previous understanding, band filling and plasma screening of Coulomb enhancement of continuum states are found to be the dominant contributions to the dispersive optical nonlinearities under quasi steady-state excitations. The partly phenomenological semiconductor plasma theory is in good agreement with the experimental data.

Full exfoliation of clay/high density polyethylene (HDPE) nanocomposites was successfully achieved with the aid of maleated HDPE (PE-g-MAn), by melt blending in a twin-screw extruder employing a long residence time configuration. The morphology of the composites was determined using wide-angle X-ray diffraction and transmission electron microscopy. The effects of clay content and state of clay dispersion on the rheological, tensile properties, and flame retardancy of nanocomposites containing very small amounts of clay, in the range of 0.05-1.0 wt %, were investigated in this study. It was demonstrated that achieving a higher degree of exfoliation for nanosized clay particles is key to enhancing the rheological, mechanical, and flame retarding properties even when small amounts of clay (less than 1%) are used.

Various pulsed logic functions (nor, xor, etc.) are performed in a high-finesse nonlinear Fabry–Perot étalon containing GaAs-AlGaAs multiple quantum wells at room temperature. Input pulses with energies less than 3 pJ incident on the device produced contrasts greater than 5 : 1 in the nor gate, and relaxation times of about 5 ns allowed us to operate the gates at 82 MHz. Thermal stability was demonstrated in the nor gate even though the device was poorly heat sunk.