Organic modulator offers high speeds at low voltages

17 Jun 2002

Researchers at the University of Washington and the University of Southern California have developed polymer-based modulators that can convert electrical signals into optical signals at a rate of up to 100 Gbit/s and a voltage of less than 1 V.

These modulators are based on a polymer matrix that contains organic molecules, known as chromophores, which have special electro-optic properties. This method for making modulators has been proposed for some years. However, in the past there have been problems caused by interactions between the electrostatic fields of the chromophores. The researchers avoided the loss of electro-optic efficiency by modifying the structure of the molecules, making them more bulky, which stops them approaching each other too closely.

Currently, electro-optic modulators are based on lithium niobate crystals. In addition to offering greater capacity and low voltages, the new polymeric materials can be integrated more easily into telecommunications systems than existing technologies. The polymer-chromophore system also generates less heat from signal loss.

These materials have not yet been incorporated into devices but the researchers anticipate practical applications for much faster telecommunications, data processing, sensing and display technologies.

Design and synthesis of the chromophores was carried out at the University of Washington. The modulators were made and integrated with silica fibers and VLSI silicon chips at the University of Southern California. Testing was carried out at Tacan Corp in Carlsbad, CA. This research was reported in the 7 April issue of the journal Science.

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Polymeric electro-optic chips in the cleanroom at the University of Southern California (USC). The cleanrooms are lit with yellow lights and protected from ultraviolet light, which would prematurely develop the chemicals that etch patterns on the chips. Image courtesy of Casey Crafton, USC News Service