Low-voltage, polarization-insensitive, electro-optic modulator based on a polydomain barium titanate thin film

A BaTiO3 thin-film electro-optic waveguide modulator with a half-wave voltage-interaction length product (VpiL) of 1.1 V cm at 1.55-mum wavelength is demonstrated. The half-wave voltage and the measured effective electro-optic coefficient are 3.3 V and 162 pm/V, respectively. The half-wave voltage increases less than 10% over a temperature range of 23-90 degreesC. Polarization-independent electro-optic modulation was observed and attributed to the polydomain structure of the BaTiO3 film. The unique combination of large electro-optic coefficient and polarization independence illustrates how engineered domain structures in ferroelectric thin films can enable properties and performance unachievable in bulk single crystals. (C) 2004 American Institute of Physics.