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Electro-optical switches developed from liquid crystals

Posted: 12 Mar 2013 ?? ?Print Version ?Bookmark and Share

Keywords:Fraunhofer? fibre-optic? liquid crystal switch? EOIW?

Optical switches and modulators based on electro optical waveguides induced in special liquid crystals have been recently developed by The Fraunhofer Institute for Photonic Microsystems IPMS Dresden.

The research institute has demonstrated a fibre-optic coupled liquid crystal switch with two switching states, based on electro-optically induced waveguides in liquid crystals (EOIW). These materials are especially sensitive to electrical fields, exhibit short response times on the sub-micron scale and feature excellent transparency over a broad spectral range, from visible to infrared.

"Large anisotropies are induced in a special liquid crystal layer within a limited region by locally applying an external electrical field. This allows a light wave to be precisely guided in this specific region", explains Technology development manager Dr. Florenta Costache. Optical loss of only 0.5 dB/cm is achieved with this guiding technique. The devices' fast switching speeds of below one microsecond as well as MHz modulation frequency arise from the use of the liquid crystals' electro-optic Kerr response to electrical fields. Although the components were developed for 1550 nm telecommunication wavelength, if desired they can be designed for any wavelength within the visible to infrared part of the spectrum (4001600 nm).

The components are manufactured using planar silicon technology, which allows cost-effective, high-volume production. The switch features a straightforward design that provides key advantages with respect to the stability and reliability of the switching process and the simple integration with other components.

This switching and modulation technology could be implemented in any complex optical system for applications such as data transfer and processing, fibre optic sensor systems and laser technologies or security.

For more information, visit the Fraunhofer IPMS website.

- Julien Happich
??EE Times

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