Optical Devices

James Young is an experimentalist concentrating on the development of new optical/photonic devices and their application to solving scientific and technical problems. His current programs focus on the physical layer of optical fiber communications. Optical communications can be divided into two general areas. Pointto-point optical fiber links are the focus of intense commercial development and application, while work on optical multi-user networks is at a earlier stage of research. His group conducts interdisciplinary research in both areas, using a combination of theory, simulations, and experiments.

Wavelength division multiplexing, the use of several distinct, wavelengths on a single fiber, is revolutionizing point-to-point optical links in the telecommunications industry. The separate wavelengths, however, are not truly independent but are coupled together by nonlinear interactions in the fiber material. A modified version of wavelength division multiplexing has been developed that significantly reduces this interference and improves performance. Testbed measurements are underway to verify calculations.

For a multiuser network the parameters of interest are the total number of users that can subscribe to the network, and the number of users that can be active simultaneously on the network for a given quality of service. The number of active users on a network is generally a small fraction of the total number of subscribers due to the bursty nature of computer traffic, but even so, network channels can have capacities exceeding a terabit per second. The user interface, which extracts the desired data from the combined data stream on the channel, must be able to process such data streams. The group has developed, demonstrated, and patented a system that uses all-optical encoders and decoders to eliminate electronic speed limitations, plus, the processing gain and number of users is independent of the transmission rate. Currently they are working on integrating the encoder/decoder onto an integrated photonics chip.