Liquid crystal on silicon technology for integrated guided wave devices

Liquid crystal on silicon (LCoS) technology has been developed in the past decade for high resolution, fast switching pixellated devices either for optical interconnections or for display applications [1][2]. In this communication, we propose LCoS technology for both linear and nonlinear integrated optic devices, in which the driving electronics can be also included on the same substrate. We describe the development of a novel process to fabricate LCoS channel waveguides made of SiO2/Si grooves filled with LC. Preliminary characterization of LCoS waveguides at both visible and optical communication wavelengths will be presented. Propagation of light launched at one end of the waveguide by butt coupling was observed for a channel length of 2 cm. The signal at the output of the waveguide could be also coupled to a second optical fiber. Both in theory and in the experiment the guided light showed a good optical confinement. The simulated output profile by means of beam propagation method was found to be very similar to the one grabbed at the output of the waveguide. It was found that only one state of input polarization could fully propagate through the whole length of the waveguide due to the contribution the LC extraordinary refractive index. The orthogonal light polarization state, for which the optical electric field “sees” only the lower LC refractive index was suppressed by more than 20 dB. This result can be explained by means of the observation of the sample under a polarized microscope of a pre-tilt angle of the molecules with respect to the propagation direction along the LC optical channel. References [1] Crossland, W. A., Manolis, I. G., Redmond, M. M., Tan, K. L., Wilkinson, T. D., Holmes, M. J., Parker, T. R., Chu, H. H., Croucher, J., Handerek, V. A., Warr, S. T., Robertson, B., Bonas, I. G., Franklin, R., Stace, C., White, H. J., Woolley R. A., & Henshall, G. Journal of Lightwave Technology, Vol. 18, No. 12, (2000) pp. 1845–1853. [2] d’Alessandro A. and Asquini R., Molecular Crystals and Liquid Crystals, Vol. 398, (2003), pp. 207-221.