Atsushi Sugiyama

Real-time spatiotemporal division multiplexing electroholography with a single graphics processing unit utilizing movie features

We propose a real-time spatiotemporal division multiplexing electroholography utilizing the features of movies. The proposed method spatially divides a 3-D object into plural parts and periodically selects a divided part in each frame, thereby reconstructing a three-dimensional (3-D) movie of the original object. Computer-generated holograms of the selected part are calculated by a single graphics processing unit and sequentially displayed on a spatial light modulator. Visual continuity enables a reconstructed movie of the original 3-D object. The proposed method realized a real-time reconstructed movie of a 3-D object composed of 11,646 points at over 30 frames per second (fps). We also displayed a reconstructed movie of a 3-D object composed of 44,647 points at about 10 fps.

Protein disulfide isomerase-P5, down-regulated in the final stage of boar epididymal sperm maturation, catalyzes disulfide formation to inhibit protein function in oxidative refolding of reduced denatured lysozyme.

In mammalian spermiogenesis, sperm mature during epididymal transit to get fertility. The pig sharing many physiological similarities with humans is considered a promising animal model in medicine. We examined the expression profiles of proteins from boar epididymal caput, corpus, and cauda sperm by two-dimensional gel electrophoresis and peptide mass fingerprinting. Our results indicated that protein disulfide isomerase-P5 (PDI-P5) human homolog was down-regulated from the epididymal corpus to cauda sperm, in contrast to the constant expression of protein disulfide isomerase A3 (PDIA3) human homolog. To examine the functions of PDIA3 and PDI-P5, we cloned and sequenced cDNAs of pig PDIA3 and PDI-P5 protein precursors. Each recombinant pig mature PDIA3 and PDI-P5 expressed in Escherichia coli showed thiol-dependent disulfide reductase activities in insulin turbidity assay. Although PDIA3 showed chaperone activity to promote oxidative refolding of reduced denatured lysozyme, PDI-P5 exhibited anti-chaperone activity to inhibit oxidative refolding of lysozyme at an equimolar ratio. SDS-PAGE and Western blotting analysis suggested that disulfide cross-linked and non-productively folded lysozyme was responsible for the anti-chaperone activity of PDI-P5. These results provide a molecular basis and insights into the physiological roles of PDIA3 and PDI-P5 in sperm maturation and fertilization.

Extremely temperature-insensitive continuous-wave quantum cascade lasers

Conspicuous temperature performances of λ ∼ 8.7 μm quantum cascade lasers with anticrossed dual-upper laser states are reported. The lasers characterized by strong super-linear current-light output curves exhibit an extremely high characteristic temperature for the threshold current density above 330 K (T0 ∼ 750 K). The slope efficiency grows with increasing temperature (a negative T1-value). In addition, for the pulsed operation of a short 1 mm length laser, the T0-value reaches a value of 1085 K above 340 K. These distinctive characteristics are attributable to optical absorption quenching in the injector as well as to suppression of carrier leakage in the active region.

A 350-nm-band GaN/AlGaN multiple-quantum-well laser diode on bulk GaN

We have demonstrated the pulsed operation of a 350-nm-band ultraviolet laser diode with a vertical current path. The laser structure was grown on a (0001)-face bulk GaN substrate. The lasing wavelength was 356.6 nm and the peak output power reached to 10 mW from the one side of uncoated facets under pulsed current operation with a pulse duration of 10 ns and a repetition frequency of 5 kHz at room temperature. The GaN substrate is expected to provide a cleaved facet configuration leading to an excellent far-field pattern as well as an advantageous thermal management solution of the devices relative to sapphire substrates. The far-field pattern of actual device on GaN substrate has been improved dramatically compared with distorted one on that of sapphire substrates.

Over 1 W record-peak-power operation of a 338 nm AlGaN multiple-quantum-well laser diode on a GaN substrate

We have demonstrated the high-peak-power operation of an AlGaN-based ultraviolet laser diode (UV-LD) with a lasing wavelength of 338.6 nm. The UV-LD structure was fabricated on a bulk GaN(0001) substrate. The broad-area and vertical conductive structure of the UV-LD, whose ridge width and cavity length were 50 and 600 µm, respectively, was employed. The threshold current density and differential external quantum efficiency were estimated to be 38.9 kA/cm2 and 8.5%, respectively. The characteristic temperature of threshold current was estimated to be 119 K, and the temperature dependence of lasing wavelength was obtained to be 0.033 nm K−1. A peak power of over 1 W has been achieved in 338.6 nm under pulsed operation at room temperature, which is the highest peak power ever obtained for AlGaN-based UV-LDs.

Acceleration of computer-generated hologram by Greatly Reduced Array of Processor Element with Data Reduction

Abstract. We have implemented a computer-generated hologram (CGH) calculation on Greatly Reduced Array of Processor Element with Data Reduction (GRAPE-DR) processors. The cost of CGH calculation is enormous, but CGH calculation is well suited to parallel computation. The GRAPE-DR is a multicore processor that has 512 processor elements. The GRAPE-DR supports a double-precision floating-point operation and can perform CGH calculation with high accuracy. The calculation speed of the GRAPE-DR system is seven times faster than that of a personal computer with an Intel Core i7-950 processor.