Search

We demonstrate a hybrid approach to detecting a short fringe period of two-photon interference with high brightness, by combining spontaneous parametric down-conversion (SPDC) and up-conversion techniques. Photon pairs were generated at the wavelength of 1550 nm via SPDC, and converted to 516.7 nm through up-conversion process with the pump light 775 nm in efficiency ∼90%. The two-photon interference of the up-converted photon pairs exhibited a fringe period of 258.3 nm with high event rate (∼2000 counts s−1), which was 6 times shorter than the original wavelength, demonstrating that the energy-time correlation of the photon pairs was preserved. The technique simultaneously provides short fringe period beyond the classical limit and high brightness of the photon pairs.

We report a high-efficiency source of cross-polarized photon pairs via type-II quasi-phase matched spontaneous parametric down-conversion using periodically poled lithium niobate (PPLN). The photon pairs are generated from the PPLN in a fifth-order quasi-phase matching condition around 800 nm, which matches the wavelength band of efficient Si avalanche photodiodes. We obtained the photon-pair production rate of 6.8×105 s-1 mW-1.

We have developed a new tapping mode-scanning near-field optical Raman microscope (SNORM) with a caved and pyramidical probe, using resonant Raman scattering and measured the stress distribution of very-large-scale integration (VLSI) standards made of the silicon dioxide film and Si. It has been found that compressive stresses of about 0.69 GPa/cm2 are concentrated on the corner of the area uncovered by silicon dioxide. The SNORM we developed has at least the spatial resolution of less than 250 nm and is a useful tool to measure image of stresses in Si devices within a short time and with a penetration depth of 5 nm.

We demonstrate efficient up-conversion detection of photons at 1550 nm utilizing bulk periodically-poled LiNbO3 (PPLN) and nanosecond-pulsed pumping. An internal conversion efficiency of 96% and an overall photon detection efficiency of 19% including the efficiency of a visible photon detector were achieved with a low dark count rate.

We have developed a high-efficiency source of cross-polarized photon pairs generated via type-II spontaneous parametric down-conversion using periodically poled lithium niobate (PPLN). The photon pairs are generated from bulk PPLN under third-order quasi-phase-matched conditions around 800 nm. We achieved a photon-pair production rate of N=1.95×106 s-1mW-1.

We have studied shape transformation of micron-sized trenches on Si substrates during high temperature hydrogen annealing, performing numerical simulations based on Mullins' theory. We have considered evaporation-condensation and surface diffusion as mass transport mechanisms causing shape transformation. The simulation allowing only surface diffusion reproduces well the observed micron-scale aspects of shape transformation by hydrogen annealing at 1000–1150°C.

This paper describes 5 1/4-in. high track-access performance magneto-optic disk drive. The drive employs a split optical system with a swing-arm actuator, the inertia of which is 160 g cm2(equivalent to a linear actuator of 10 g weight). An avarage seek time was estimated less than 35ms in the absence of latency. It is noticeable that both its mechanism and control systems are very simple.