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The characteristics of Schottky junctions made with diamond films of different unepitaxial crystallite and pyramidal hillock densities were studied. Also, the superiority of Schottky junctions made from the films of the step-flow mode was explained and compared with those made from the conventional growth mode. Schottky junctions exhibited high-rectification properties with minimal leakage current at reverse bias and were more sensitive to surface flatness and film quality.

A transmission differential phase-contrast microscope with a split detector is used as a readout system for a multilayered three-dimensional optical memory. The system is applicable to data recorded as refractive-index changes. The system is compact and easy to use. The three-dimensional optical transfer function for the system is derived. This shows that the spatial bandwidth of the system is the same as that of a conventional microscope with incoherent illumination but with much improved contrast. Six layers of information are recorded in a photopolymer and are read out with little cross talk and high contrast. Key words: Optical memory, photorefractive, differential phase-contrast microscope, three-dimensional optics, nonlinear optics, holographic memory.

We analyze the three-dimensional refractive-index distribution that is induced locally when a laser beam is focused onto a very small region in a photorefractive crystal. The formation of the index distribution is deduced from the temporal behavior of the electron density distribution in the crystal under non-steady-state conditions. The density distribution is computed by the use of a set of the recurrence relations that was derived from Kukhtarev's equations, which describe the transport of electrons in time. In particular, we calculated the index distribution formed in Fe-doped LiNb[O.sub.3] crystals. To verify the validity of our analysis, we read, by using a phase-contrast microscope, refractive-index dots that were recorded in Fe-doped LiNb[O.sub.3] crystals. A good agreement was obtained between experimental results and the calculated phase-contrast images when the characteristics of the imaging system are taken into account. We also found that the induced index change is largest when the c axis of the LiNb[O.sub.3] crystal is oriented parallel to the polarization direction of the reading beam. Under this optimal condition, we succeeded in recording up to 10 layers of readable data in a LiNb[O.sub.3] crystal.

A technique of speckle-noise reduction for an image amplified by two-wave coupling with a photorefractive crystal is proposed. The spatial coherence for the axis along the fringe formed in the photorefractive crystal is reduced to remove the speckle, but the spatial coherence for the axis vertical to the fringe is unaltered. This is obtained by rotating a mirror to deflect the illumination beams one dimensionally for both the signal and reference patterns during the exposure of the hologram. Because of the image-holography configuration, the images of the signal and the reference do not move on the photorefractive crystal as the two beams deflect. The beam deflection can be faster than the response of the photorefractive crystal. Some experimental results for the image amplification with the technique developed are presented, and they are compared with results obtained without speckle-noise reduction. Fringe deformation caused by deflection of the signal and reference beams is analyzed.

A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF) throughout the heavy ion beam (HIB) driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may produce a time-dependent implosion acceleration, which reduces the Rayleigh-Taylor (R-T) growth [Laser Part. Beams 11, 757 (1993), Nuclear Inst. Methods in Phys. Res. A 606, 152 (2009), Phys. Plasmas 19, 024503 (2012)] and the implosion nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ∼ 1 GHz [Phys. Rev. Lett. 104, 254801 (2010)]. Three-dimensional HIBs illumination computations present that the few % wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency.

A remarkable ion energy increase is demonstrated for post acceleration by a laser-plasma booster. An intense short-pulse laser generates a strong current by high-energy electrons accelerated, when this intense short-pulse laser illuminates a plasma target. The strong electric current creates a strong magnetic field along the high-energy electron current in plasma. During the increase phase in the magnetic field, a longitudinal inductive electric field is induced for the forward ion acceleration by the Faraday law. Our 2.5-dimensional particle-in-cell simulations demonstrate a remarkable increase in ion energy by several tens of MeV.

A remarkable improvement is presented on the energy conversion efficiency from laser to protons in a laser-foil interaction by particle simulations. The total laser-proton energy conversion efficiency from laser to protons becomes 16.7%, though a conventional plane foil target serves a rather low efficiency. In our 2.5-dimensional particle-in-cell simulations the Al multihole structure is also employed, and the laser absorption ratio reaches 71.2%. The main physical reason for the enhancement of the conversion efficiency is a reduction of the laser reflection at the target surface area;

This study investigates a target for heavy ion fusion (HIF) using light target materials. In this study, the target structure, the heavy ion beam (HIB) input pulse shape and the HIB input pulse energy are optimized for the maximal fusion energy output. We performed two-dimensional fluid implosion simulations to obtain a high pellet gain. The optimized target shows a high yield of a gain 223. The input Pb beam energy is 1.8 MJ.