Abstract: Apparatus for monitoring and displaying the status of a local area network. The network includes a hub with ports for connection to various data terminal equipment in a star configuration and for connection to other hubs of the network. The hubs each have different types of plug-in modules which have ports for connecting the hub to different types of network cable such as fiber optic cable, unshielded twisted pair cable and shielded twisted pair cable. Information is automatically provided to a control console identifying the types of modules and the location of the modules in the hub so that an image of the actual hub can be displayed on the screen of the control console. The actual hub image shows the location and types of modules installed in the hub. In addition, information regarding the connection of each of the hubs to other hubs of the network is obtained and provided to the control console.

Abstract: An active repeater for a star configured communications network includes a threshold detector for collision detection. Whenever two or more terminals simultaneously feed data into the repeater, a threshold sensitive collision detector is triggered to logically isolate the data from the output of the repeater and to logically substitute a predetermined collision signal therefor, thereby causing the competing terminals to reset to retry the transmissions at randomly selected later times.

Abstract: There is disclosed a method of fabricating an optical waveguiding surface layer in an optically transparent crystalline substrate, such as lithium niobate, by selectively indiffusing metal ions, such as titanium, into the crystal to effect an increase in the index of refraction of a surface portion thereof. The indiffused metal ions serve to raise both the ordinary and extraordinary refractive indices of the substrate by amounts which are of the order of one percent at the diffusion surface and which gradually decrease by one-half at depths of the order of one micrometer below the surface. By properly adjusting the relevant diffusion parameters in the method, the important surface waveguide characteristics can be independently controlled.

Abstract: By randomly varying the difference in the phase constants and/or the coupling coefficient along the lengths of two or more wavepaths, an equal division power divider is obtained whose operation is not critically dependent upon its dimensions.

Abstract: An integrated optically-controlled 4-port bistable switch having a waveguide directional coupler as one of its elements is disclosed. A photodetector is positioned so as to be sensitive to the optical energy at one output port of the directional coupler and the voltage developed by this photodetector is coupled to electrode elements of the directional coupler. The resulting bistable device permits such functions as remote optical switching to be performed.

Abstract: Acoustical and optical surface wave filters are described wherein the filter characteristic near resonance is provided by cascaded grating resonators. The out-of-band suppression for these resonators is provided by a track changing element that includes a four-port directional coupler having one port connected to receive input energy and a fourth port connected to couple energy into the cascaded grating resonators. Tapered and chirped reflection gratings are positioned so as to selectively reflect energy present at the second and third ports of the directional coupler. In a surface acoustic wave embodiment of the invention, the directional coupler is provided by a multistrip coupler. In an optical embodiment, the directional coupler function is provided by waveguiding structures that are brought sufficiently close to induce 3 dB coupling.

Abstract: An integrated optical filter composed of coupled nonidentical strip waveguides in LiNbO.sub.3 is disclosed. The device has a broad bandwidth, is tunable over several hundred angstroms, and offers electrical control of the crossover efficiency. Several devices are combined on a single substrate to provide an electrically tunable multiplexer or demultiplexer.