Optical modulator based on electro-optically induced waveguides

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