Yutaka Honda

Serially grafted optical waveguide fabrication of NLO polyimide and transparent polymers

We have investigated polymers suitable for fabricating serially grafted optical waveguide with nonlinear optical (NLO) polyimide (PI). UV cured epoxy resins were appropriate not only as a cladding layer for the NLO PI but also as a core layer of the grafted waveguide. By using NLO PI as an active core layer and the UV cured epoxy resins as a passive core layer, serially grafted waveguide was fabricated. The scattering loss of the serially grafted points was relatively small. The serially grafted waveguide is applicable to many types of practical optical circuits.

High-speed light modulation using complex refractive-index changes of electro-optic polymers

We propose a promising type of light modulator using complex refractive-index changes of electro-optic polymers in the wavelength region of absorption. The material used in this study is a high-glass-transition-temperature active-polyimide thin film. The wavelength dependence of electrically induced complex refractive-index changes and the modulation efficiency are evaluated. A modulation efficiency of 33.8% has been realized with 141 V rms applied potential at a wavelength of 633 nm. Very fast modulation at over 25 MHz has been demonstrated.