Abstract: The local area optical network interconnects a plurality of user terminals. The local area network includes an interface unit for receiving information from the user terminals and an active star node connected to the interface unit by fiber optic cables. In one embodiment, the active star centered node includes a passive optical star coupler having a plurality of ports for interconnecting the terminals. An optical receiver receives optical signals from the star coupler and is interconnected with an optical transmitter which transmits the signal from the receiver back into the star for distribution to the plurality of ports. In either embodiment, the star node includes an expansion port and an optically associated transmitter and receiver to allow multiple nodes to be connected to one another in an hierachial, branching architecture. In another embodiment, the active star centered node includes a passive input star coupler and a passive output star coupler.

Abstract: The wavelength division multiplexer/demultiplexer includes a gradient index of refraction (GRIN) lens and a diffraction grating located adjacent to one end of the GRIN lens. The diffraction grating is adapted for switching from a first angle to a second angle with respect to the GRIN lens. For both path and terminal equipment redundancy, first and second input optical fibers are located at first and second input locations on an end surface of the GRIN lens. A first and a second plurality of output optical fibers are also located on this end surface of the GRIN lens. The input and output optical fibers are located so that optical energy will travel from the first input optical fiber to the first plurality of output optical fibers when the diffraction grating is oriented at the first angle and optical energy will travel from the second input optical fiber to the second plurality of output optical fibers when the diffraction grating is oriented at the second angle.

Abstract: A graded index of refraction (GRIN) lens/diffraction grating combination is used to monitor the output source peak wavelength of an optical source. As the output wavelength of a source varies, different detectors are activated. The output of these detectors is used to control a thermoelectric cooler which will raise or lower the temperature of the source so as to drive the output wavelength toward the desired peak output wavelength.