Kazunori Shiota

Electro-optic and dielectric characterization of ferroelectric films for high-speed optical waveguide modulators

We investigate the electro-optic properties and high-frequency relative dielectric constants of epitaxially grown lanthanum-modified lead zirconate titanate (PLZT) and polycrystalline barium titanate (BaTiO3) films in a high-frequency range of up to 40 GHz for designing a high-speed ferroelectric thin-film modulator. We also demonstrate a ferroelectric thin-film Mach-Zehnder-type waveguide modulator using the epitaxially grown PLZT film. The use of a composite structure with a low dielectric coefficient substrate and a buffer layer enabled of a ferroelectric thin-film waveguide modulator with 40-Gb/s operation.

A 13 C 2 H 2 frequency-stabilized, polarization-maintained erbium fiber ring laser with no frequency modulation

We have constructed a new¹³C<inf>2</inf>H<inf>2</inf>frequency-stabilized fiber laser whose output beam has no frequency modulation. The frequency stability reached as high as 1.8 × 10^-10for τ of 1 s, and 1.5 × 10^-11for τ of 100 s.