180 Park Ave - Building 103
Florham Park, NJ
Subject matter expert in Free Space Optical Communications devices and applications and terahertz communications, spectrum devices and applications
Biographical information
January 2010
David M. Britz is AT&T’s subject matter expert for Free Space Optical Communications (FSOC) and the Terahertz initiative. He is a Principal Technical Staff Member with AT&T Labs Research - Shannon Labs and has worked at AT&T contiguously for 25 years. Over the years his principal activities have included forward looking technologies and advanced product design and development including public communications products, ISDN telephones, advanced speakerphones, in-building and terrestrial optical wireless.
From 1994 he became the project leader for AT&T’s internal development and applications of commercial FSOC technologies, and later, after the break up of AT&T and Lucent and the change in AT&T’s research direction, he initiated and continued investigations and industry collaborations on the utilization of FSOC for broadband local access networks, and later meshed based FSOC backbone applications for broadband Wireless Local Area Networks. Since mid 2007 he has been focused on the technologies and network applications utilizing extreme bandwidth sub-millimeter (terahertz) frequencies for multi-gigabit wireless links for next generation terahertz based communications and Personal Area Networks.
He is a founding board member and has served as the Chairman of the FSO Alliance, a USA delegate to the IEC on laser safety and founding member of IEC-TC76 Working Group 5 part 12 (FSOC operation standards). He is an active member of IEEE 802.11 standards organization and in late 2007, successfully lobbied and initiated the Terahertz Interest Group in 802.15, accepting the Vice Chair position of that group. The THz IG was formed to investigate applications and prepare standards for this next generation multi-Gigabit wireless area networks and PAN’s utilizing THz spectrum, and to engage with the ITU on impending THz spectrum allocations.
He is multiply published and provides regular FSOC and THz presentations to internal and external AT&T customers and external subject related conferences. Over his career he has been granted 15 patents. On a personal note, he is married to Jeanne, has two adult children Helen and Peter and is an active amateur astronomer and telescope maker for 35 years and is now learning to make his own wine.
Secure Open-Air Communication System Utilizing Multi-Channel Decoyed Transmission,
December 7, 2010
A secure, open-air communication system utilizes a plurality of "decoy" data signals to hide one or more true data signals. The true data signal(s) are channel hopped with the plurality of decoy data signals to form a multi-channel "scrambled" output signal that is thereafter transmitted in an open-air communication system. The greater the number of decoy signals, the greater the security provided to the open-air system. Further security may be provided by encrypting both the true and decoy signals prior to scrambling and/or by utilizing a spatially diverse set of transmitters and receivers. Without the knowledge of the channel assignment(s) for the true signal(s), an eavesdropper may be able to intercept (and, with time, perhaps descramble) the open-air transmitted signals, will not be able to distinguish the true data from the decoys without also knowing the channel assignment(s).
Optical/Radio Local Access Network,
July 21, 2009
A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path coupled to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure is due to fog.
Optical/radio local access network,
November 13, 2007
A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path couples to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links to corresponding users, an optical switch coupled to the plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure by monitoring channel losses in a first link, the received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure sensed is due to fog.
Metropolitan networks based on fiber and free space access distribution system,
October 9, 2007
An architecture for facilitating wavelength-specific and packet-switched routing comprises a primary metropolitan fiber ring, a primary distribution/aggregation node in the primary metropolitan fiber ring and a local service domain further comprising a secondary aggregation node in communication with the primary distribution/aggregation node. A network to provide local metropolitan switching and routing and broadband local access distribution described in terms of its component layers comprises a distribution/aggregation routing layer that interfaces with a primary fiber metropolitan ring and a local customer primary distribution/aggregation node via transport branches of a mesh architecture, a local distribution and routing layer that routes specific wavelengths and newly assigned wavelengths to and from a customer's premises and a cross-connect layer that handles customer specific wavelength and packet routing via one of fiber, millimeter wave radio and free space optical communications.
Optical/radio local access network,
September 25, 2007
A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path couples to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links to corresponding users, an optical switch coupled to the plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure by monitoring channel losses in a first link, the received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure sensed is due to fog.
Optical/radio local access network,
August 22, 2006
A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path couples to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links to corresponding users, an optical switch coupled to the plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure by monitoring channel losses in a first link, the received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure sensed is due to fog.
Optical/radio local access network,
March 7, 2006
A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path couples to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links to corresponding users, an optical switch coupled to the plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure by monitoring channel losses in a first link the received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure sensed is due to fog.
Metropolitan networks based on fiber and free space access distribution method,
January 3, 2006
A method for facilitating wavelength-specific and packet-switched routing comprises the steps of demultiplexing wavelengths propagating on a primary metropolitan fiber ring, determining a destination address for the wavelength, accessing a look-up table, determining if the destination address matches a local address contained in the look-up table and switching the wavelength based on a result of the determining step. A method for providing local metropolitan switching and routing and broadband local access distribution described in terms of the functions of the layers comprises the steps of interfacing with a primary fiber metropolitan ring and a local customer primary distribution/aggregation node via transport bran ches of a mesh architecture, routing specific wavelengths and newly assigned wavelengths to and from a customer's premises and handling customer specific wavelength and packet routing via one of fiber, millimeter wave radio and free space optical communications.
Metropolitan networks based on fiber and free space access distribution system,
December 6, 2005
An architecture for facilitating wavelength-specific and packet-switched routing comprises a primary metropolitan fiber ring, a primary distribution/aggregation node in the primary metropolitan fiber ring and a local service domain further comprising a secondary aggregation node in communication with the primary distribution/aggregation node. A network to provide local metropolitan switching and routing and broadband local access distribution described in terms of its component layers comprises a distribution/aggregation routing layer that interfaces with a primary fiber metropolitan ring and a local customer primary distribution/aggregation node via transport branches of a mesh architecture, a local distribution and routing layer that routes specific wavelengths and newly assigned wavelengths to and from a customer's premises and a cross-connect layer that handles customer specific wavelength and packet routing via one of fiber, millimeter wave radio and free space optical communications.
Free Space Duplexed Optical Communication With Transmitter End Multiplexing And Receiver End Amplification,
February 15, 2005
A free space wavelength duplexed system includes first and second terminals. The first terminal includes an optical transmitter and an optical receiver. The optical receiver has a telescope, an optical to electrical converter and an optical amplifier coupled between the telescope and the optical to electrical converter. A method includes the steps of receiving a received optical signal through a telescope, diverting the received optical signal in an optical splitter into an optical amplifier, and transmitting a transmit optical signal through the optical splitter to the telescope. Another method includes the steps of receiving plural received optical signals through a telescope, diverting the plural received optical signals in an optical splitter into an optical amplifier, separating the plural amplified optical signals by wavelength, and transmitting plural transmit optical signals at distinct wavelengths through the optical splitter to the telescope.
Optical/radio local access network,
September 7, 2004
A communication system includes a plurality of nodes and a plurality of point-to-point links that interconnect the plurality of nodes into a network. Each node includes an optical switch to controllably route a plurality of in-ports of the optical switch into a plurality of out-ports of the optical switch. Each point-to-point link includes a free space optical channel. A first free space optical channel couples to a first node through a receive path and through a transmit path. The receive path couples to a respective in-port of the optical switch of the first node, and the transmit path couples to a respective out-port of the optical switch of the first node. In an alternative embodiment, a communication hub includes a plurality of neighborhood links to corresponding users, an optical switch coupled to the plurality of neighborhood links, and a trunk coupled between the optical switch and a free space optical channel link to the network. A method of communicating in a network having plural links includes sensing the presence of a received signal failure by monitoring channel losses in a first link, the received signal failure resulting from at least one of rain and fog. The method further includes sending data in a free space optical channel of the first link when the received signal failure sensed is due to rain and sending the data in an RF channel of the first link when the received signal failure sensed is due to fog.
Free space duplexed optical communication with transmitter end multiplexing and receiver and amplification,
May 11, 2004
A free space wavelength duplexed system includes a first and second terminals where each terminal includes a receiver part and a transmitter part, and the receiver includes a telescope, and optical-to-electrical converter, and an optical amplifier coupled between the telescope and the optical-to-electrical converter.
Free space optical communication link with diversity,
May 4, 2004
A free space communication system includes first and second terminals, and the first terminal includes a transmitter to transmit an input signal. The transmitter has plural laser sources, at least one optical delay line and a telescope. Each laser source modulates the input signal onto a wavelength that is distinct from a wavelength of each other laser source. The plural laser sources include a first laser source and at least one other laser source, and the at least one optical delay line is coupled to a respective output of the at least one other laser source. The telescope projects an output of the first laser source and an output of each of the at least one optical delay line toward the second terminal. Alternatively, a free space communication system includes first and second terminals, and the first terminal includes a transmitter to transmit an input signal. The transmitter has at least one electrical delay line, plural laser sources and a telescope. The at least one electrical delay line delays the input signal. The plural laser sources include a first laser source and at least one other laser source, the first laser source modulates the input signal onto a first wavelength, and each of the at least one other laser source modulates an output of a corresponding electrical delay line onto a wavelength that is distinct from the first wavelength. The telescope projects an output of each of the plural laser sources toward the second terminal.
Mirror control of micro-electro-mechanical optical cross connect switch,
July 30, 2002
An optical switch includes an input optical fiber, an output optical fiber and a mirror that is either inclinable or rotatable or both and reflects a lightwave signal from the input optical fiber into the output optical fiber. The switch further includes a control circuit to sense a misalignment error and to adjust the mirror to correct the misalignment error. The misalignment error may be either an inclination misalignment error, a rotation misalignment error or both. In an alternative embodiment, an optical switch includes an input optical fiber that includes an input core and an input cladding, an output optical fiber that includes an output core and an output cladding, an input GRISM to insert a calibration signal into the input cladding and a mirror that is adjustable. The mirror reflects a lightwave signal from the input core into the output core and reflects the calibration signal from the input cladding into the output cladding. The optical switch further includes an output GRISM to extract the calibration signal from the output cladding and a control circuit to sense a misalignment error based on the extracted calibration signal. The misalignment error includes an inclination misalignment error or a rotation misalignment error or both. The control circuit includes circuitry to adjust the mirror to correct the misalignment error. In an alternative embodiment, an optical switch includes an input optical fiber, an output optical fiber and a rotatable mirror that has diffraction gratings etched thereon. The mirror reflects a lightwave signal from the input optical fiber into the output optical fiber. The optical switch further includes a control circuit to adjust a rotation angle of the mirror to select a wavelength that can be diffracted into the output optical fiber according to a spacing of the diffraction gratings.
High dynamic range free-space optical communication receiver,
September 19, 2000
A free-space optical communications system and method in which a transmitter transmits a free-space optical communication beam to an optical receiver. The receiver includes an optical detector, an optical input level sensor and an optical attenuation device. The optical detector detects the optical communication beam, while the optical input level sensor senses an optical input level of the optical communication beam at the optical detector and outputs a control signal corresponding to the sensed optical input level. The optical attenuation device is responsive to the control signal by attenuating the optical input level of the optical communication beam to be less than a predetermined input level. The optical input level sensor includes a detector optical level sensor, a comparator circuit and a controller. The detector bias level sensor senses an optical level of the optical detector. The comparator circuit is coupled to the detector bias level sensor and compares the sensed optical level of the optical detector to predetermined threshold levels. The comparator circuit outputs a code signal relating a magnitude of the sensed optical level of the optical detector to the predetermined thresholds. The controller is responsive to the code signal by outputting the control signal.
Backlighting scheme for a multimedia terminal keypad,
April 4, 2000
A housing assembly for an ISDN multimedia capable wireless interface device having a plurality of operating capabilities. The housing assembly comprises a main housing, a cover, hinge assembly for coupling the cover to the main housing. The hinge assembly enables the cover to pivot and articulate relative to the main housing to transform the housing assembly into a plurality of mechanical configurations via sensors responsive to the pivoting and articulating of the cover provided in the housing assembly. The cover includes an illuminated keyboard having a display for selectively providing pixel-based graphics and light. The keyboard is disposed over the display when the device is operating in one of a plurality of operational modes. Each keypad of the keyboard has an image viewing surface and coherent light pipe mechanism for conducting light generated by the display to the image viewing surface the keypad. The upper rear surface of the main housing includes three unmarked softkeys which enable finger access for various device functions. The keys are software controlled and as such operate to provide a mouse, cursor control, number and text generation, video camera control and other like device features.
Beam steering and tracking of laser communication links by dual-quadrant tracker and photodiode assembly,
August 4, 1998
At the reception site of a laser transmission system the received laser light beam is converted into a focusing cone of light. The cone of light is directed to partially illuminate the inner area of the quad photo detector array which is used to provide a highly accurate positional measurement of the laser beam. A quad photo detector is utilized to measure deviation of the laser beam from its ideal line-of-sight and provide sensing signals defining the deviation to enable its corrective adjustment. A high speed photo detector located centrally to and behind a central aperture of the quadrant photo detector permits the detection of the laser light beam voice and data.
Personal communicator having orientable video imaging element,
May 9, 1995
A personal communicator for use in a wireless communication network includes a wireless communications LCD and a multimedia LCD with the communications, mounded on a hinged member, and superimposed on top of the multimedia LCD. The communications LCD is sufficiently transparent to permit viewing of the under multimedia LCD. Each provides visual information to the user relative to the present use of the communicator. The selected use of the communicator is primarily responsive to the open or closed position of the hinged keyboard supporting cover. When the hinged member is closed the communicator operates in a communication mode. When it is open the communicator operates primarily in a multimedia mode. The personal communicator includes a steerable video imager for controllably optimizing image field coverage and adjusting to the orientation of the user relative to the personal communicator. The video imager includes an optical lens set and the imager is mounted on a mounting shaft so as to allow controlled rotation about its axis. The video imager includes mechanical apparatus interactive with the hinged keyboard supporting cover to reset its orientation to a standard position when the cover is closed and allow differing orientations when the cover is open.
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