Novel Design of Z-Cut Lithium Niobate Electrooptic Modulator

Analysis and optimisation of ultra-high-speed Z-cut lithium niobate (LN) electrooptic modulator, operating at a high frequency region, by using full wave finite element numerical technique has been demonstrated. Investigation of the effects of adjusting the buffer layer thickness, the electrode height and the waveguide trapezoidal profile on the microwave effective index (Nm), the characteristic impedance (Ζc), the microwave losses (αc) and the half-wave voltage-length product (VπL) has been reported. Optimisation of the above parameters yield to a novel design of LN modulator with a low VπL and high bandwidth operating at a frequency range between 1-100 GHz. The frequency dependent dispersion of the key device parameters with aim to determine the device suitability for high speed operation has been demonstrated.