Liquid Crystal Waveguides

Light propagation in an EOIW with a liquid crystal core with increasing electric field strength.
© Fraunhofer IPMS
Light propagation in an EOIW with a liquid crystal core with increasing electric field strength.

We developed an innovative concept of electro-optically induced waveguides in isotropic phase liquid crystals (LC-EOIW) on a silicon backplane. Characteristics such as low loss and sub-microsecond response time stem from the use of liquid crystals of large electro-optic Kerr coefficients and excellent transmission over a broad wavelength (400 – 1600 nm) as core layers in the EOIWs design. The waveguides can be configured to provide various optical functionalities such as n × m switching, variable optical power splitting, variable optical attenuation or modulation. This technology is open to the most versatile applications. The components could be used, for example, in optical telecommunication or in fiber optic sensor networks. These variable waveguide components are also attractive from the viewpoint of manufacturing. Due to their straightforward design, they can be manufactured using silicon wafer technology and as such can be easily integrated and adjusted according to the desired application.

Furthermore polarization insensitive LC-EOIWs have been developed with very low polarization dependent loss (PDL) on a wide attenuation range. In this particular case, by employing a special electrode arrangement in the waveguide design, both TE and TM polarized light waves could propagate simultaneously inside the waveguide with the same but variable transmitted power.