Abstract: Integrated mechanical angular alignment-enhancement structures for incorporation into free-space micromachined optical switches are capable of achieving better than 0.1° micro-mirror angular precision and repeatability with the optical switches. The structures open the path to high port-count crossconnects with sufficiently low loss for deployment in practical optical-communications networks.

Abstract: The present invention provides a variety of methods and apparatus for monitoring signal quality and switch operation for optical switches in an optical cross connect. The signal quality can be checked by using a beamsplitter to reflect a portion of the light beam carrying the signal onto a photodetector which is connected to a device which can monitor loss of signal, loss of frame, and other transmission characteristics. The position of a switch or waveguide can be monitored by circuits which detect variable levels of resistance and capacitance based on the switch's position or by reflecting probe light beams off the back of the switching mirror. The present invention also provides a method for determining if the signal quality photodetector is functioning correctly.

Abstract: A trunk and branch logical ring network includes a plurality of nodes that are coupled to a ring backbone by a plurality of branching units. The connections to the ring backbone are such that physically adjacent nodes are not adjacent to one another logically in the network. By providing this alternating branching arrangement the maximum length of any unregenerated span along the ring is significantly reduced. This reduces repeater spacing in the network.

Abstract: A non-blocking crossconnect apparatus includes a primary bi-directional crossconnect device and a plurality of secondary bi-directional crossconnect devices. The primary crossconnect device has a plurality of pairs of bi-directional signal ports. A first one of each of the plurality of pairs of the bi-directional signal ports are arranged in a first set and a corresponding second one of each of the plurality of pairs of the bi-directional signal ports are arranged in a second set. Each secondary crossconnect device is associated with a respective one of the plurality of pairs of bi-directional signal ports and has a pair of secondary bi-directional signal ports and a pair of bi-directional signal leads.

Abstract: Integrated mechanical angular alignment-enhancement structures for incorporation into free-space micromachined optical switches are capable of achieving better than 0.1° micro-mirror angular precision and repeatability with the optical switches. The structures open the path to high port-count crossconnects with sufficiently low loss for deployment in practical optical-communications networks.

Abstract: A method and apparatus for minimizing optical loss associated with light beam divergence in a free-space micro-machined optical switch is presented. The coupling efficiency of a free-space micro-machined optical switch, that is, how efficiently the switch transfers an optical light beam from an emitting optical fiber to a receiving optical fiber, is obtained by calculating the overlap integral of the wave functions of an optical beam taken in a free-space mode at an entry point in the switch and in a fiber mode at a receiving fiber facet of the optical switch. Since the optical light beam diverges as it propagates through the optical switch, and the propagation distance increases with mirror size, that coupling efficiency is limited by the ratio of the optical light beam radius and the mirror radius of the switch.

Abstract: Integrated mechanical angular alignment-enhancement structures for incorporation into free-space micromachined optical switches are capable of achieving better than 0.1° micro-mirror angular precision and repeatability with the optical switches. The structures open the path to high port-count crossconnects with sufficiently low loss for deployment in practical optical-communications networks.

Abstract: A method and apparatus for curvature-resistant micro-mirror structures to reduce light beam coupling loss due to mirror curvature in free-space micro-machined optical switches is presented. As a significant contributor to light beam coupling loss is the curvature of the micro-mirrors in these cross-connect systems, an improved thick mirror slab utilizing a phosopho-silicate glass (PSG) core is constructed. The PSG core is sandwiched between two poly-silicon layers, thus providing an enhanced, bending-resistant structure which protects the PSG core from the release etchant used in surface micro-machining and substantially reduces mirror curvature. The reflective layer is laid down on top of the enhanced, bending-resistant structure.

Abstract: Integrated connection-verification system for use in a micro-electro-mechanical system (MEMS) crossconnect device. The system uses application of a dithering signal such as a sinusoidal bias to an electrode plate associated with a micro-mirror switching element to dither the micro-mirror. The optical signal from the dithering micro-mirror is fed through a beam splitter, a portion of the optical signal thus being directed to a photodetector. If intensity modulation in the optical signal corresponding to the frequency of the dithering signal is detected by the photodetector associated with the micro-mirror, the connection path between the desired input and output ports is verified.

Abstract: A symmetrical optical matrix crossconnect apparatus includes a plurality of optical switch devices with each comprising a first pair of fiber optic ports, a second pair of fiber optic ports and a reflective element. The first pair of fiber optic ports are disposed apart from one another and aligned coextensively along a first optical path. One of the first pair of fiber optic ports emits a first light beam that travels along the first optical path in free space while the remaining one of the first pair of fiber optic ports receives the first light beam. The second pair of fiber optic ports are disposed apart from one another and aligned coextensively along a second optical path. A first one of the second pair of fiber optic ports emits a second light beam that travels along the second optical path in free space while a remaining one of the second pair of fiber optic ports receives the second light beam. The first optical path and the second optical path crisscross each other at an intersection.

Abstract: A bridging apparatus is used with an optical matrix crossconnect mechanism that has an array of reflective panels that are disposed in a plurality of columns and rows and are selectively operative between reflective states and non-reflective states. The bridging apparatus includes at least one light beam splitting device that is peripherally disposed in the array of reflective panels adjacent to an entry position of a light beam. The at least one light beam splitting device is operative in a retracted state to permit the light beam to enter into the optical matrix crossconnect mechanism in an undivided manner. The at least one light beam splitting device is operative in a beam splitting state so that the light beam entering into the optical matrix crossconnect mechanism can be divided into a first light beam portion and a second light beam portion which are directed into the optical matrix crossconnect mechanism in different directions.

Abstract: The specification relates to a repeaterless branch powered fiber optic communications system. The system comprises an optical fiber cable trunk, configured in ring topology, with one or more telecommunications hub, and one or more branching unit serially interconnected therein. Branching units are provided as convenient add/drop points along the trunk ring from which branch fiber optic cable radially extend to cable stations. Cable stations insert and extract telecommunications traffic from the trunk ring over the branch fiber optic cables. In addition, the branch fiber optic cables are also coupled to light emitting power sources. The branch fiber optic cables deliver the energy produced from these power sources to optical amplifiers serially embedded within the branch fiber optic cables, the branching units, or the optical fiber cable trunks. The optical amplifiers convert the energy delivered from the branch fiber optic cables into amplified telecommunications signals.