Takumi Kato

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We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation(More)
We generate broad bandwidth visible light ranging from 498 to 611 nm via third-harmonic generation in a silica toroid microcavity. The silica toroid microcavity is fed with a continuous-wave input at a telecom wavelength, where third-harmonic generation follows the generation of an infrared Kerr comb via cascaded four-wave-mixing and stimulated Raman(More)
A novel model for the mechanical joint impedance, which takes into account the force-velocity relationships of skeletal muscles, is proposed. First, velocity-dependent viscosity changes are formulated using the equation proposed by A. V. Hill. Then, human wrist joint impedance is estimated by a conventional model (a linear model) and the proposed novel(More)
We demonstrated the deterministic generation of blue light emission (438 nm) via the third-harmonic process from an infrared pump by carefully engineering the dispersion of a high-quality-factor whispering gallery mode microcavity. We present two different approaches to obtaining broad bandwidth light. One is based on a clustered comb and the other employs(More)
Comb generation in different mode families via a stimulated Raman scattering (SRS) process is studied using a silica toroid microcavity. The broad gain bandwidth of SRS in silica allows us to excite longitudinal modes at long wavelengths belonging to mode families that are either the same as or different from the pump mode. We found through experiment and(More)
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