What is a Liquid Crystal Waveguide?

The Brief Explanation:

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Waveguides are optical structures used for communications.  When a signal in the form of light enters a waveguide, it is channeled along a path towards a desired outlet.  By channeling these signals, one can set up complex communications networks that use fast fiberoptics rather than traditional copper wire.  By using liquid crystals to produce these waveguides we could potentially reduce the cost of production and allow for integration of these waveguides directly into fiberoptic cables, allowing for more direct switching and fewer necessary cable lines.

The Thorough Explanation:

Liquid Crystals and Polymer

For an explanation of liquid crystals and their interaction with polymers, please see the H-PDLC page.

Photolithography

Photolithography is the process of transferring shapes from a mask onto the surface of a sample.  In our photolithography experiments we place a mixture of polymer and liquid crystal between two glass slides, with spacers making sure the thickness of the film remains uniform.  Then a mask is placed over the sample and exposed to light.  When the light reaches the sample it cures the polymer.  However, in the areas covered by the mask the liquid crystal diffuses from the polymer and remains in these dark areas.  By using a mask shaped like a waveguide the sample is able to take on the shape of a liquid crystal waveguide without the need for etching.  By incorporating resonators and alternate pathways, this waveguide could be turned easily into an optical switch, which would transfer the light signal from one channel to another.

Why Study Liquid Crystal Waveguides?

This technology will be simple and cost-effective to produce and will allow for integration of local optical switches within fiberoptic networks.  This will result in a more direct cable network and will greatly reduce the infrastructure required to bring fiberoptic technology to both residential and commercial applications.  Additionally, the low cost of the device will allow the switches to be used in environments best suited for disposable devices (e.g. oceans, rough climates, etc.). The knowledge gained from this project can be applied further towards fabricating additional photonic structure in the LC/polymer set (e.g. couplers, ring resonators, etc.) to explore the possibility of extending the advantages of an LC/polymer substrate to the larger field of photonic communication devices.