Researchers steer beams with integrated optical modulators
As part of a long-term investigation of integrated optics in silicon-on-insulator structures such as SIMOX (separation by implantation of oxygen), researchers at the University of Surrey (Guilford, England) and the University of Southhampton (Southhampton, England) have demonstrated the principle of using the interference pattern of several coherent optical sources to form and steer an optical beam. The steering results from varying the relative phase of the sources--in this demonstration case, the output of two integrated optical waveguides excited by an unpolarized 1550-nm-output diode laser. A standard SIMOX wafer produced by Spire (Bedford, MA) was modified with a buried n+ layer, which allows buried contacts that can be common to all optical modulators controlling the phase of each of the outputs.
Graham Reed, one of the researchers, says this structure makes it possible to construct arrays of outputs with minimum complexity. He says the grou¥will continue improving performance of optical devices in SIMOX, which has the advantage of low cost, although it can suffer from power limitations in the current application. The grou¥is also interested in the potential of working with high-quality silicon carbide because it retains many of the advantages of silicon technology together with much-higher speed and efficiency. A complex optical beam-steering device could find use in an optical switch or multiplexer.
