Abstract: A method and system for effectuating network routing over primary and backup channels. In one embodiment, a primary link is enabled to transfer customer traffic between network nodes, while a transmission quality of the link is monitored. Upon determining the primary link has entered a marginal state, the primary link is disabled such that the network immediately determines it is unavailable. Test traffic is sent over the primary link while monitoring the transmission quality to determine if the link returns to a non-marginal state, and in response thereto the primary link is re-enabled such that the network immediately determines it is available for routing customer traffic again. In one embodiment, rerouting the customer traffic is effectuated by opening and closing the primary link, such that it appears to the network to be disconnected and reconnected. In one embodiment, the primary link comprises a free space optical (FSO) link.

Abstract: A communication system communicates control data in unused segments in the data stream of an asynchronous channel. The communication system includes a transmitting unit and a receiving unit. The transmitting unit transmits communications data to the receiving unit via the asynchronous channel, in compliance with the channel's asynchronous protocol. However, the transmitting unit transmits control data to the receiving unit in unused segments of the data stream.

Abstract: A free space optical tap and multi/demultiplexer unit includes at least one optical unit that can tap off an optical signal from and/or add an input optical signal to a received FSO signal. The optical unit propagates the resulting optical signal, via free space, to a next optical unit of the system. The optical unit can include a holographic grating to diffract a portion of the received FSO signal to an optical detector and/or diffract an input optical signal to form part of a free space optical output signal. In addition, the FSO signal can include component signals of different wavelengths, with each optical unit of the system being wavelength specific to a different one of the wavelengths of the FSO signal.

Abstract: An apparatus for transmission of free space optical communication system signals employing a spatially-extended light source and method of using the same. A laser beam source directs an optical signal into a free end of a segment of multimode fiber. As the optical signal passes through the segment of multimode fiber, the optical signal is converted into a mode-scrambled optical signal. This mode-scrambled signal may then be used as a spatially-extended light source that is directed outward as an optical beam through the use of a collimating lens.

Abstract: A spontaneous data communication network includes antenna/transceiver sets located in mobile (e.g., vehicles such as cars, buses, trucks, ferries, etc.) or stationary units (e.g., computers, manufacturing equipment, office furniture, office equipment, road signs, overpasses, bridges, etc.). Each antenna/transceiver set directs network traffic based on optimizing a merit function or penalty function to reduce costs of congestion for stochastically changing demands and flows in a data communication system. The routers exchange values with neighboring routers. Based on the exchanged values and values local to a router, flow conditions are checked and if necessary the local values are adjusted until the flow conditions are satisfied or a time period expires. Adjustments are associated with optimizing a merit function or penalty function.

Abstract: A link quality agent running in a computer embedded in a device, such as an optical communication transceiver, to monitor an optical signal quality of the link. In one embodiment, avalanche photodiode (APD) and filter wheel values on each side of the free space link as well as packet errors from a distribution switch are monitored. When the link quality agent determines that the free space link is marginal (based on the monitored optical signal quality), the link quality agent configures down the port between the distribution switch and the router on the receive end of the free space link, and forces customer traffic over a backup link. When both ends of the free space link are again functional, the link quality agent configures the port up and routes customer traffic to the free space link.

Abstract: One embodiment of the present invention generates random samples for a Bernoulli distribution. A first covariance matrix is generated using a desired mean vector and a desired covariance matrix of the Bernoulli distribution. A normal vector is constructed using the desired mean vector and the first covariance matrix. A sampling vector is generated using the normal vector and a threshold vector. The sampling vector has the desired mean vector and the desired covariance matrix.

Abstract: Apparatus and methods for implementing a high-power or high-sensitivity tracking mode of operation in a free-space optical communication system are disclosed. Functions of the high-power or high-sensitivity tracking mode may be implemented in response to one or more engage signals generated and transmitted in response to a sensed inclement weather condition, such as fog or the like, which may interfere with communication of an optical signal between a pair of free-space optical terminals in the free-space optical communication system. Implementation of the high-power or high-sensitivity tracking mode facilitates maintenance of the alignment between the pair of free-space optical terminals throughout the duration of the inclement weather condition to allow data communication to resume fully after the inclement weather condition has diminished.

Abstract: Systems and methods for the transmission of auxiliary data via a modulated carrier signal superimposed on a primary data communication signal between terminals of a free-space optical communication system are disclosed. The carrier signal is modulated with an auxiliary data signal via phase-shift keying, amplitude-shift keying, frequency-shift keying, or other suitable modulation technique, and superimposed on the primary data communication signal prior to transmission as an optical signal by a transmitting free-space optical terminal. The primary data communication signal is received by at least one photo detector coupled to a receiving free-space optical terminal that demodulates the primary data communication signal to reconstruct the auxiliary data.

Abstract: A window-mounted positionable collector comprising a base that is secured to a window. An inner rotatable hollow wedge-cut member may be rotated about the base to produce a first degree of freedom, while an outer rotatable hollow wedge-cut member may be rotated about a top end of the inner rotatable hollow wedge-cut member to provide a second degree a freedom. The combination of the first and second degrees of freedom enables the optical axis of an optical collector operatively coupled to the outer rotatable hollow wedge-cut member to be directed along any direction falling within a cone of angulation defined by acute angles corresponding to the angles of the wedge cuts defined in the rotatable hollow wedge cut members. In one embodiment, a cover is connected to a top end of the outer rotatable hollow wedge-cut member to form a sealed volume, whereby the apparatus may be secured to the window by applying a vacuum to the sealed volume.

Abstract: A free space point-to-multipoint optical transceiver has a reflective element and an optical feed mounted on the reflective element. When the optical feed is coupled to a light source, the optical feed is positionable to direct light received from the light source onto a reflective surface of the reflective element. Light directed onto the reflective surface is reflected towards a remote location to be received by a receiver located at the remote location. By adjusting a position of the optical feed, the reflected light is aimed. Therefore, adjusting the position of the optical feed provides a technique to track moving remote locations and/or to target different remote locations.

Abstract: A mode scrambler comprises an optical fiber adapter having a diffuser disposed between optical fiber mating ends of the optical fiber adapter. When a single mode optical signal is launched in the mode scrambler, the mode scrambler converts the single mode optical signal to a multimode optical signal that has a substantially even intensity distribution across the modes.

Abstract: Apparatus, system, and method for enabling eye-to-eye contact in video conferences. In general, the system and apparatus employ means for generating video images corresponding to real images that would be produced if a video camera were disposed at or behind a video display having a field of view directed toward a target object such as a participant. An image (either real, reflected, or holographic) is formed based on light reflected off of the target object, and object light corresponding to the image is received by the video camera, which produces a video signal containing the image. Typically, the means for generating the video images employs direct imaging, reflective imaging, or holographic imaging. The means for generating the video images are also configured in such a manner as to be substantially transparent to video conference participants viewing the display images on the video display.

Abstract: A holographic optical element (HOE) device is mounted in wireless optical telecommunication system transceiver. The HOE device includes a developed emulsion material having an interference pattern recorded thereon, sandwiched between a pair of elements, such as a pair of clear glass plates. In operation, the HOE device uses the recorded interference pattern to diffract received light rays towards an optical processing unit of the system receiver. A transmitter unit can be positioned at least in part behind the HOE device. An opening in the emulsion material allows a light signal transmitted from the transmitter unit to be substantially unaffected by the recorded interference pattern. The transceiver can also include a spotting scope and an alignment beacon.

Abstract: An apparatus and method for combining multiple optical beams into mode-scrambled optical signals. In one embodiment, the apparatus includes a plurality of laser beam sources, each to produce a modulated optical beam. A plurality of input fiber segments, each comprising a multimode optical fiber core, are operatively coupled at one end to a respective laser source to receive a respective modulated optical beam. A multimode optical beam combiner is used to operatively couple the output ends of the input fiber segments to the input end of an output fiber segment having a multimode optical fiber core. The modulated optical beams produced by the laser beam sources are combined into a single mode-scrambled optical signal. The apparatus enables multiple optical beams having similar wavelengths to be combined to increase optical signal strength. It also enables multiple optical beams having different wavelengths to be combined to form a wavelength division multiplexed signal.

Abstract: A fast steering mirror for use in free space optical communication systems. The fast steering mirror includes a gimbaled movement comprising an outer gimbal pivotally coupled to a base member and an inner gimbal pivotally coupled to the outer gimbal. A mirror that is posited by the apparatus is coupled to the inner gimbal. A first pair of voice coil drivers including a pair of magnetized stators fixedly coupled to the base member and a pair of voice coils fixedly coupled to the outer gimbal are provided along with a second pair of voice coil drivers comprising a pair of magnetized stators coupled to the base member and a pair of voice coils coupled to the inner gimbal. Selectable drive currents may be provided to the windings in the voice coils to position the mirror. In one embodiment, the fast steering mirror further includes a reference position seek mechanism.

Abstract: A method and apparatus for improving the transmission of a free-space optical communications signals through windows having surface imperfections. A void-filling material is applied to one or both surfaces of the window to fill any non-flat surface voids on those surfaces in areas through which an optical communications signal passes. In one embodiment, one or two substantially perfect optically translucent plates are mounted to the imperfect surface(s) of the window so as to capture the void-filling material between an inside surface of each optically translucent plate and the imperfect surfaces of the window. The void-filling material is selected to have an index of refraction that substantially matches an index of refraction for the window at an optical wavelength corresponding to the free-space optical communication signal.

Abstract: An optical fiber assembly includes an optical fiber and ferrule. The ferrule's face is partitioned into several regions. Optical elements can be formed on the regions to diffract light incident on the ferrule. Alternatively, the ferrule's face may have several reflective facets. Light incident on the end of the optical fiber propagates to a communications detector. Light incident on the ferrule's face is redirected to tracking detectors, each arranged to receive the redirected light from a preselected region of the ferrule. The output signals of the tracking detectors are used to adjust the alignment between the incident light and the assembly. Alternatively, tracking fibers or a quadrant cell may be used to directly receive light that would otherwise be incident on the ferrule's face.

Abstract: Optical transceivers include a diffractive optical element (DOE) attached to a surface of a prism or other optical support. The DOE is configured to direct an input optical signal to a planar or curved reflective surface, or receive an output optical signal from the planar or curved reflective surface at angles greater than a critical angle in the prism. In some examples, the optical support includes one or more curved reflective surfaces and the DOE is a hologram. Such optical transceivers include a reflective surface that is rotatable with respect to the DOE, or with respect to a selected communication direction and the DOE for selection of a transmission or reception direction. The optical supports of such optical transceivers can be mounted to a window, and include a reflective region configured to total internally reflect optical signals. Selection of a communication direction is based on a rotation of the rotatable reflective surface.

Abstract: An apparatus and method for generating a mode-scrambled optical signal. A laser beam source directs an optical signal into a free end of a first segment of multimode fiber comprising a graded-index (GI) fiber core at an offset from the centerline of the core, generating an offset-launch condition. The first segment of multimode fiber is operatively coupled into a second segment of multimode fiber comprising a step-index (SI) fiber core. As the offset-launched optical signal passes through the first and second segments of multimode fiber, the optical signal is converted into a mode-scrambled optical signal having a substantially-filled numerical aperture.