Berlin 2005 – scientific programme

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DF: Dielektrische Festkörper

DF 10: Elektrische, elektromechanische und optische Eigenschaften

DF 10.5: Talk

Tuesday, March 8, 2005, 15:20–15:40, TU EMH225

Holographic reflection filters in photorefractive LiNbO₃ channel waveguides for applications as add/drop multiplexers — •Daniel Runde and Detlef Kip — Clausthal University of Technology, Institute of Physics and Physical Technologies, Leibnizstr. 4, 38678 Clausthal-Zellerfeld

A slanted refractive index grating in a bi-modal waveguide section breaks the orthogonality of the fundamental and first order mode. It couples the forward propagating fundamental mode into the backward propagating first order mode. A mode selective coupler splits the reflected signal from the passing signal into a drop channel. In a symmetrically designed device, a second coupler works as the add channel. The gratings are recorded with the green light of a Nd:YVO₄ laser (λ = 532 nm) in photorefractive LiNbO₃:Ti:Cu channel waveguides operating in the infrared wavelength region around 1.55 µm. The bandwidth (FWHM) of these gratings is about 0.1 nm and makes the filter applicable for DWDM telecommunication devices. Due to the electrooptic effect the Bragg wavelength is adjustable by applying a bias electric field. A modulation of the electric field allows switching of the filter.