Research at CMMPE — Devices & applications — Liquid crystals for telecommunications

 

The forcasted growth of internet traffic requires a shift in technology. Devices will have to be more integrated and compact, yet consume less energy and hence generate less heat. Liquid crystal technology is a potential candidate for solving some of the most pressing technological challenges.

In this research we are investigating the use of ferroelectric liquid crystals (FLCs) in telecommunication devices. The simplest device consists of an FLC cell placed between crossed polarisers. This device is then inserted in-line with a single mode optical fibre. With such a device, we can achieve binary switching and also variable (analogue) optical attenuation by applying a moderate electric field across the FLC. We have observed optical rise times of 10 microseconds or less, with an extinction ratio between on and off states of 60dB.

Ongoing work is directed towards the integration of such FLC devices with optical waveguides. In future this type of device might be the building block of complex optical circuits on a chip.

Possible applications of this device are channel equalisation in WDM networks, active polarisation control, reconfigurable networks and bandwidth provisioning.