Regensburg 2002 – scientific programme
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DS: Dünne Schichten
DS 27: Postersitzung
DS 27.26: Poster
Tuesday, March 12, 2002, 15:30–17:30, Poster Physik B
FERROELECTRIC BaTiO3 THIN FILM OPTICAL WAVEGUIDE MODULATORS — •Adrian Petraru, Jurgen Schubert, Martin Schmid, and Christoph Buchal — Institut für Schichten und Grenzflächen (ISG1-IT), Forschungszentrum, 52425 Jülich, Deutschland
High quality BaTiO3 epitaxial thin films on MgO substrates have been grown by pulsed laser deposition. Both, c-axis and a-axis BaTiO3 orientation were studied. Mach-Zehnder optical waveguide modulators with a fork angle of 1.7 deg. have been fabricated by ion beam etching. The waveguides are of the ridge type, the BaTiO3 thickness is 1 µ m, the ridge step 50 nm, the width 2 µ m. Light was coupled into the waveguides from optical fibers. The BaTiO3 waveguide propagation losses are 1-2 dB/cm. Electrodes of 3 mm length were deposited besides the waveguides. Electro-optic modulation has been demonstrated with Vπ = 6.3V at 632nm wavelength and Vπ = 9.5V at 1550nm wavelength for the a-axis samples and with Vπ = 8V at 632nm wavelength and Vπ = 15V at 1550nm for the c-axis samples. Theoretical modelling of the Mach-Zehnder modulators for both crystalline orientations of the BaTiO3 films gave the Pockels coefficients r51 =80 pm/V for the c-axis film and an effective Pockels coefficient reff = 734 pm/V for the a-axis films at 632 nm wavelength.