Transparent polycrystalline YAG ceramics with nearly the same optical characteristics as those of a singlecrystal were fabricated by a sintering method using > 99.99 mass% purity powder. The average grain size andpore density of Nd: YAG ceramics obtained were several ten μm and about 1 ppm, respectively. A cwoscillation experiment using present Nd: YAG ceramics was performed by a diode laser pumping in the regionof 808 nm. The laser performance of the Nd: YAG ceramics was equivalent or superior to those of high-qualitycommercial Nd: YAG single crystal by the Czochralski method.

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This paper describes the recent progress for ultraprecision machining of functional optical materials havingpeculiarities such as physical anisotropy, softness, brittleness, deliquescence, and narrow phase matching angleacceptance. Those peculiarities introduce the difficulty for producing optical surfaces by using the conventionaloptical polishing process. Both single point diamond turning and ultraprecision grinding can produce opticalsurfaces on such functional optical materials under very special machining conditions. The relation betweencrystallographic orientation and machining direction is important for producing optical surfaces on nonlinearoptical crystals. Machining fluid is also a key factor in such processes.

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Photo-induced surface modification of plastics was accomplished with an ArF excimer laser in the presence ofchemical solutions. The chemical stability of the plastics is attributed to the presence of C-H, C-F or C=Obonds. Mechanism of this surface modification is to pull the terminal atoms from C-H or C-F bond in theplastic surface and to substitute the functional group for the dangling bond of C. In this treatment, the chemicalsolution was sandwiched between the sample surface and silica glass window by capillary phenomenon. Then, the solution and sample surface were excited with UV photons. In addition, the sample surface was dehydrogenatedor defluorinated by the H or B atoms which were photodissociated from H₂O or B (OH) ₃ in an aqueous solution, and the photodissociated OH radicals were substituted for unbonding chain of C. As a result, the plasticssurface were photochemically modified to have hydrophilic, oleophilic or metallic properties.

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Using the world's strongest permanent magnet develops an active attitude control system. The system isdesigned for a wide variety of applications, which rely on pneumatic vibration isolation systems. Its applicationsrange from precision laboratory environment to semiconductor manufacturing equipment, which demands theoptimum noise performance and platform stability as well as to improve settling time and increase productivity.

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Recent advances in optical materials for vacuum ultraviolet (VUV) lithography are reviewed from a view of interaction of excimer laser light with materials. Synthetic silica glasses applicable for F₂ excimer laser totally differs from those for KrF and ArF lasers. A novel phenomenon was found in H₂-impregnated SiO₂ glasses byirradiation with F₂ laser light pulses, i. e., bleaching of VUV absorption edge. Degradation of optical transmissionat 193 nm of calcium fluoride single crystals is primarily determined by the concentration of specific impuritycations such as Y³⁺ and Tb²⁺. Time resolved fluorescence was an effective technique to make screening of the fluoride crystals with high tightness to ArF laser pulses.

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Effect of ion beam etching on laser-induced surface damage was investigated in CsLiB₆O₁₀ (CLBO) crystaland fused silica. In high-power UV lasers, these optical surfaces were damaged due to absorption of thepolishing compound embedded inside the surface. From SIMS analysis, the polishing compounds were foundto be embedded in the CLBO and fused silica surfaces to a depth of 60 nm. These polishing compounds couldbe removed by using Ar ion beam etching. No ion beam-induced surface damage was observed when theapplied ion beam voltage was less than 200 V. Due to the effect of polishing compounds removal on damageresistivity, the laser-induced surface damage threshold of CLBO was improved up to 16 J/cm2 (wavelength: 355 nm, pulse width: 0.85 ns) as compared with that of the as-polished surface 11 J/cm². The laser-inducedsurface damage of fused silica also increased from 7.5 J/cm² to 14.5 J/cm².

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Application potential of multistory optical waveguide structure (MSWG) to intra-board, intra-wafer, or intrachipoptical interconnection systems is discussed with proposed coupling scheme between stacked waveguidesusing grating couplers. Basic concept of three dimensional optoelectronic integrated circuits (3-D OEICs), which is constructed by stacking several wafer-scale electronic IC (EIC) layers and optical IC (OIC) layers, isfigured and described. Number of micro-processors, memories, light sources, photodetectors, etc., are integratedon each EIC layer of semiconductor wafer of several micron thickness. Optical data-bus and control-bus areformed in each OIC layer with MSWG, which is introduced between EIC layers. Use of grating couplers forselective interconnection among MSWG or OIC layers is proposed and discussed with preliminary experimentalresults.

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Simulated results of two-dimensional plume distribution in urban areas were verified using a UV lidarsystem. Nitric oxide emitted from diesel engines on the roof of a building was used as a tracer in lidarmeasurements. The solid-state lidar system with a Ti: sapphire and Nd: YAG lasers has recently beendeveloped for nitric oxide measurements. The output pulse energy achieved was 4 mJ at 226.8 nm with a 2 pmlinewidth. Distribution was calculated by k-ε turbulence model in computational fluid dynamics (CFD) code.Comparison of the horizontal distribution between lidar and simulated data shows a difference of spread, caused by the assumption in the model of the same turbulence along all axial directions.

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Niobium (Nb) -doped KTiOPO₄ (KTP) has been investigated. We report the crystal growth of Nb-doped KTP, the effects of content variation of Nb dopant on the phase-matching properties, and our success in obtaining 90°non-critical phase matching (NCPM) of Nd: YAG 1064 nm laser. We also present an analysis in thecorrelation between the NCPM and variation in the content of Nb dopant and the decreasing effect of Nbdoping on the phase-matching cutoff wavelength of KTP.

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