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Optical modulator based on electro-optically induced waveguides

: Blasl, Martin; Hartwig, Haldor; Bornhorst, Kirstin; Costache, Florenta

Verhandlungen der Deutschen Physikalischen Gesellschaft 48 (2013), No.4, Paper Q43.62
ISSN: 0420-0195
ISSN: 0372-5448
Deutsche Physikalische Gesellschaft (DPG Frühjahrstagung) <2013, Hannover>
Fraunhofer IPMS ()

Optical modulators are used to dynamically control the power of signals transmitted in optical fibre networks.
We report on a new design of an optical modulator based on electro-optically induced waveguides (EOIW) in isotropic phase nematic liquid crystals. These materials exhibit, just above their clearing temperature, unusually high electro-optical Kerr coefficients and therefore they are particularly suitable for this EOIW concept.
We fabricated an EOIW based optical modulator-chip by means of silicon technology. The chip assembly includes structured wafers bonded together and enclosing in between a liquid crystal layer. The bottom wafer comprises stripe aluminium electrodes, which define the induced waveguide region, as well as V-grooves for precise fibre to EOIW coupling.
For the modulator chip, we demonstrate a modulation bandwidth (-3 dB) of 5 MHz and an extinction ratio of 12 dB. The insertion loss is 3 dB, which is in agreement with FEM-simulations. Additionally, we analysed the influence of voltage induced phase transition on the performance of the chip.