Abstract: A free-space wavelength division multiplexing system is provided having a demultiplexer and receiver arrangement. The demultiplexer and receiver arrangement may be based on a rotatable interference filter. A desired wavelength can be selected by adjusting the angle of the interference filter with respect to the incoming light beam. Alternatively, the demultiplexer and receiver arrangement may be based on a diffraction grating. Multiple wavelengths of light are diffracted at different angles, which spatially separates each wavelength in the system. A corresponding multiple-element linear photodetector array is used to receive the spatially separated optical signals.

Abstract: The present invention encompasses an apparatus and method for supporting multiple wireless data communication networks between a wireless communications device and a fixed communications device or another wireless communications device. Two network elements compose the physical apparatus, a protocol converter and a router. Upon receiving packet data from a fixed communications device, a router will locate a destination wireless communications device. The router will then convert the packet data to a format usable by the wireless data network that the wireless communications device is currently using for wireless access. After conversion, the router will perform actual transmission of the packet data to the correct destination wireless network. Once the converted packet data is received by the wireless network base station, it will be transmitted via RF to the destination wireless communications device.

Abstract: A system is provided for tracking a free-space optical communications beam. The incoming beam is split by a beam splitter. One portion of the incoming beam is focused onto a high-speed photodetector. Another portion of the incoming beam is passed through a target pattern optical element. A resulting target pattern is formed on a two-dimensional active pixel sensor array. The alignment of the system can be adjusted based on the position of the target pattern on the sensor array.