Singlemode channel waveguides and electrooptic modulators in KTiOPO/sub 4/ for the short visible wavelength region

Abstract

Single-mode channel waveguides at short visible wavelengths have been fabricated in KTiOPO/sub 4/ by Rb/spl rlhar2/K ion exchange in mixed melts of RbNO/sub 3/-KNO/sub 3/-Ba(NO/sub 3/)/sub 2/. The technological parameters have been chosen by means of theoretical WKB- and calculations concerning the singlemode region of the effective channel waveguide index N/sub 00/ at the given wavelength. Great diffusion anisotropy and small dispersion of the surface refractive index change guarantee singlemode operation of the very same channel waveguide from the blue up to the red. Typical attenuation of about 2.0 dB/cm for TM- and 1.5 dB/cm for TE polarization was obtained at /spl lambda/=0.5145 /spl mu/m. Light-induced refractive index changes (photorefractive effect) have been determined as a function of time, wavelength, guided optical mode intensity and temperature. The light-induced effects in Rb/spl rlhar2/K ion-exchanged channel waveguides in KTiOPO/sub 4/ are about two orders of magnitude smaller than those in annealed proton-exchanged channel waveguides in LiNbO/sub 3/. Electrooptic phase modulators have been successfully investigated concerning dynamic V/sub /spl pi// measurements, the electric-optical field overlap and dc-drift phenomena. Design, fabrication and experimental results of integrated-optic Mach-Zehnder-interferometer modulators for short visible wavelengths are presented. >