Yoshimaru Nakata

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Ultrasonic motors have some special unique features, such as high-torque under low-speed operation, compact size, and no electromagnetic noise. Ultrasonic motors would be expected to apply an element of the artificial muscle. The driving principle of the ultrasonic motor is based on friction force between a rotor and a stator. Therefore, it is difficult to(More)
We demonstrate the low-noise and high-gain operation of a fluoride Er/sup 3+/ and Ce/sup 3+/ codoped fiber (F-ECDF) amplifier with 980-nm pumping. A 980-nm-pumped F-ECDF with a length of only 45 cm exhibits a noise figure of <4.5 dB in the entire C-band and a small signal gain of >20 dB with a gain ripple of <1 dB without any gain-flattening filter in the(More)
Two types of diphenyldiazomethanes having two trifluoromethyl and two bromine groups at the ortho positions, either in unsymmetrical or in symmetrical fashion, that is, (2,6-dibromo-4-phenylphenyl)[4-phenyl-2,6-bis(trifluoromethyl)phenyl]diazomethane (U-1-N2) and bis(2-bromo-4-phenyl-6-trifluoromethylphenyl)diazomethane (S-1-N2), are prepared. Triplet(More)
Fiber laser operating property at 1.55-/spl mu/m band in a newly developed Ce,Er:ZBLAN fiber by a continuous-wave laser diode pumping at 980 nm is presented. The output characteristics of the Ce,Er:ZBLAN fiber laser system are analyzed in detail based on the rate equations model by taking into account the energy transfer between Ce/sup 3+/ and Er/sup 3+/(More)
A unit-cell of the array with vacuum window, except plasma and chamber, is analyzed by the GSM-MoM analysis and the array is designed for uniform aperture illumination. Uniform aperture illumination on the quartz glass strips is observed by the near field measurement using 1/5 scale model antenna, and validity of the analysis/design is confirmed. Aperture(More)
Single-layer slotted waveguide arrays (SWA) are promising candidates for generating a large area plasma. The analysis for one slot in a SWA with a complex external structure with the assumption of two dimensional periodicity in the external region is demonstrated with a simplified model. This model is analogous to that for a dual-polarized waveguide slot(More)
Er-doped heavy-metal fluoride glass, because of its wider emission bandwidth around 1500 nm, which spans the most important communications window, now has been investigated as one of the most promising materials for wide-band optical fiber amplifier, which would be of great value in the future wavelength division multiplexing (WDM) optical fiber(More)
We describe the fabrication of Ti:sapphire thin films by pulsed laser deposition (PLD) and their optical characteristics. The reduction of droplets, which is always problematic in PLD, with a high-speed rotating target is also presented to achieve a low loss optical film.