Integrated-optical high power amplitude modulator for the visible wavelength range in KTP

Summary form only given. Color image generation is an important application for amplitude modulators working in the visible spectral range. A suitable candidate is the integrated-optical Mach-Zehnder interferometer in KTP [Ruske et al. 1998]. However. Due to the very small cross section of its singlemode waveguides it can only be used for low power applications. In order to overcome this limitations, we realized a novel modulation device using large cross section waveguides with high optical damage threshold, the so called asymmetric diffraction amplitude modulator (ADAM) [Pertsch and Wachter 1999]. This device is based on a diffraction zone embedded asymmetrically between an input and an output waveguide. In the off-state the light is diffracted asymmetrically because of the reflecting boundary. At the end of the diffraction zone only a negligible fraction of light couples into the output waveguide. To switch the device to the on-state, the refractive index of a barrier region is reduced by applying a voltage to an appropriate pair of electrodes due to the electro-optical effect. This barrier creates a waveguide connecting the input and output.