To handle the recent increase in data traffic, in optical telecommunication systems multiple optical signals are sent onto a single fiber and then must be de-multiplexed with great accuracy, namely separated with a controlled power level on multiple channels. Scientists at the Fraunhofer IPMS developed a unique concept of on-chip integrated liquid crystal waveguides, which – when voltage is properly set on a specific electrode arrangement – are able to rapidly and precisely control the optical power transmitted from one fiber to another. Specifically, multiplexing schemes based on this waveguide concept feature low optical loss over a wide wavelength range from VIS up to IR range (400-1600 nm), switching times between channels of less than 100 ns and wide variable attenuation range and splitting ratio due to the (analog) voltage controlled optical transmission. Through patented designs, these waveguides can be configured for both polarization maintaining and/or polarization independent applications with low polarization dependent loss (PDL < 0.1 dB).

This waveguide technology finds applications in optical telecommunication but also in fiber optic sensor networks and laser systems, thus wherever there is a need to control the power (optical signals) distribution in fiber optic networks.

The Fraunhofer IPMS offers as evaluation kits variable optical attenuators (VOAs), variable power splitters (VPSs) and switches based on this waveguide technology. Customized designs are possible and these could include – integrated on that same chip – combinations of switches, VOAs and VPSs with multiple input and output ports. Such designs can be adapted to the customers’ requirements for performance, light coupling geometry and footprint.

Visitors to the European Conference on Optical Communication ECOC, Europe's largest meeting place for optical communication, which will be held in Valencia from September 28 - 30, 2015, can have a look at compact, fiber-coupled silicon-liquid crystal waveguide based modules demonstrating the aforesaid optical functions for fiber optic networks. The Fraunhofer IPMS exhibition can be found at the booth 812.