High tilt angle FLC SLM for optical interconnects

Optically transparent switching has become a vital part of the modern vision of telecommunications networks. Integral to this is an optically transparent switch that is polarisation insensitive and capable of low loss and low crosstalk. The recent ROSES (reconfigurable optical switches for telecommunications and aerospace applications) project has demonstrated the feasibility of an all-optical switch based on holographic beam steering using a ferroelectric liquid crystal (FLC) spatial light modulator (SLM). This project demonstrated that for low loss switching, a high tilt angle FLC material has to be used in the SLM. For this reason, a prototype 3×3 optical switch was built using a transmissive glass SLM containing the commercially available FLC material CS2005 which possesses a tilt angle of 43°. The ROSES switch called for a silicon backplane SLM, however, due to the voltage limitations of the CMOS circuitry, the principles were first tested with a transmissive glass SLM