Lucent Technologies Inc.

At&t Bell Laboratories

Lgs Innovations LLC

Other

Caci, Inc. - Federal

Alcatel Lucent

American Telephone & Telegraph Co., At&t Bell Laboratories

American Telephone and Telegraph, Co.

Thomas Huntington Wood

Clinton R Giles

Robert D Feldman

Xiang Liu

Gordon Cook Wilson

Robert William Tkach

Gerald Nykolak

Tingye Li

Yacov Cohen

James Albert Walker

David A Miller

Mark David Feuer

Joseph Earl Ford

Paul Francis Wysocki

Rodney C Alferness

Dietrich Marcuse

John L Zyskind

Enrique A Marcatili

Atul Kumar Srivastava

Arthur C Gossard

Theodoor Charlouis Damen

Daniel S Chemla

Andrew Russell Grant

Douglas P Holcomb

Stephan Frank Wielandy

John A Stiles

Peter P Bohn

Methods, devices, and systems are described for free space optical communication. An example method can comprise generating a first linearly polarized optical signal and converting the first linearly polarized optical signal to a first circularly polarized optical signal. The first circularly polarized optical signal can be output into free space. The method can comprise converting a second circularly polarized optical signal, received via free space, to a second linearly polarized optical signal. The second linearly polarized optical signal can have a linear polarization different than a polarization of the first linearly polarized optical signal. The method can comprise directing, via a polarizing beam splitter, the second linearly polarized optical signal to a first path separate from a second path from which the polarizing beam splitter received the first linearly polarized optical signal.

Optical communication terminal for bidirectional communication

Methods, devices, and systems are described for free space optical communication. An example method can comprise generating a first linearly polarized optical signal having a wavelength and a first type of linear polarization and converting the first linearly polarized optical signal to a first circularly polarized optical signal. The first circularly polarized optical signal can be output into free space. The method can comprise converting a second circularly polarized signal, received via free space using the wavelength, to a second linearly polarized optical signal. The second linearly polarized optical signal can have a second type of linear polarization different than the first type. The method can comprise directing, via a polarizing beam splitter, the second linearly polarized optical signal to one or more detectors configured to output data.

A free-space optical communication system is provided. The free-space optical communication system includes a transmitter configured to optically transmit data in a plurality of subcarrier signals over a free-space scattering medium. The free-space optical communication system includes a coherent receiver configured to receive the plurality of subcarrier signals and extract the transmitted data from the plurality of subcarrier signals after traversal over the free-space scattering medium.

Free-space optical communication system and method in scattering environments

The present application is directed an optical communication method. The method includes a step of receiving a signal at a single-polarization receiver. The method also includes a step of detecting, through the single-polarization receiver, the signal including a symbol with a pulse position modulation pulse and an additional modulation. The method also includes a step of decoding a first portion of bits carried by the symbol based on a position of the PPM pulse. Further, the method includes a step of decoding a second portion of the bits at the position through an additional modulation. The application is also directed to an apparatus for optical communication. In addition, the application is directed to an optical communication method which recovers two polarization components form the signal each carrying independent data. Further, the application is directed to an optical communication method that recovers two frequencies of the detected signal.

Methods and systems for optical detection

An apparatus transmits data using a format where information bits intended for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through pulse position modulation (PPM) format and the rest of which are encoded through an additional modulation format on each PPM pulse. The additional modulation format for the PPM pulse may be at least one of a polarization-division-multiplexed (PDM) modulation, phase-shift keying (PSK) modulation, polarization shift keying (PolSK) modulation, amplitude modulation (AM), quadrature-amplitude modulation (QAM) modulation, or a combination thereof. In one embodiment, the additional modulation of the PPM pulses is through polarization-division-multiplexed quadrature-phase-shift keying (PDM-QPSK). The unique combined use of PDM-QPSK and PPM produces much higher receiver sensitivity than either PPM or PDM-QPSK alone.

System, method, and apparatus for high-sensitivity optical detection

An apparatus receives data encoded in a format where information bits for transmission are mapped into symbols each carrying a plurality of bits, some being encoded through a pulse position modulation (PPM) format and some being encoded through an additional modulation format on at least one PPM pulse. A receiver detects the signal through a dual-polarization coherent receiver front-end, recovering polarization components of the signal by decoding a first non-zero portion of a plurality of bits carried by a symbol based on slot position of at least one PPM pulse in the polarization components and a second non-zero portion of the plurality of bits carried by the symbol based on the additional modulation carried by at least one PPM pulse in the polarization components. Pilot-assisted single-carrier frequency-division equalization (PA-SC-FDE) may be used for reliable signal reception in the presence of severe PPM errors.

An optical amplifier comprises at least two gain regions, an intermediate region situated between the gain regions, and a transition region situated between the intermediate region and each gain region. The aforesaid regions have claddings that collectively form a path for pump radiation propagating from at least one of the gain regions to the other gain region, and cores that collectively form a path for signal radiation propagating from at least one of the gain regions to the other gain region. The cores in the gain regions support multiple propagating optical modes, including at least one signal mode and at least one non-signal mode. The intermediate region, however, supports fewer propagating core modes than are supported by the gain regions. The transition regions are conformed such that when radiation in propagating non-signal core modes passes from the gain regions into the intermediate region, it is at least partly coupled into cladding modes of the intermediate region.

Cladding-pumped optical amplifier having reduced susceptibility to spurious lasing

A data communications system which provides multiple logical channels on a passive optical network (PON) using subcarrier multiple access (SCMA). The PON includes multiple optical network units (ONU) which each communicate with a head-end over a logical channel. Collisions among upstream transmissions are thereby avoided and high speed Ethernet service over large distances is made possible.

System for operating an Ethernet data network over a passive optical network access system

The linearity and noise performance of an inexpensive optical signal source are improved using either feedback or feedforward correction techniques. In a feedback embodiment of the invention, a modulation signal, such as a broadband analog CATV signal, is applied to the optical source along with an error signal. The error signal is generated in a feedback path using a high-speed photodiode to detect a portion of the output optical signal generated by the optical source. A delay compensation filter in the feedback path corrects for variations in error signal delay as a function of frequency, such that source nonlinearity and noise may be corrected over a broad bandwidth. In a feedforward embodiment of the invention, an error signal generated from a portion of the output of the optical source is converted to a frequency band outside of the modulation signal bandwidth before being applied to an input of the optical source. A receiver receiving the optical signal detects both the converted error signal and the modulation signal, and uses the detected error signal to correct the detected modulation signal for the nonlinearity and noise effects of the optical source. The invention allows inexpensive optical sources, such as digital-grade DFB laser diodes or Fabry-Perot laser diodes, to be used in place of expensive highly-linear, low-noise sources in analog signal transmission and other important applications.

Apparatus and methods for improving linearity and noise performance of an optical source

A passive optical network is provided that integrates signals carrying broadcast CATV services into a FTTH/C network that also provides high-speed Internet access and telephony. Essentially all residential telecommunications services are provided in a single network, based on a single fiber and a single simple transceiver in an optical network unit. Multiple services (e.g., analog video, digital video, cable-modem based Internet access) are multiplexed using separate rf subcarriers (subcarrier multiplexing or SCM) and the delivered signals are compatible with existing consumer appliances (e.g., TVs, VCRs, cable modems, etc.). The system and method combines a bi-directional network with dedicated upstream and downstream networks so that the most expensive and extensive portion of the network (the bi-directional outside plant infrastructure) need not be duplicated for each direction, while the use of two separate dedicated upstream and downstream networks further upstream facilitates flexible provisioning of bandwidth for each direction independently.

Subcarrier modulation fiber-to-the-home/curb (FTTH/C) access system providing broadband communications

A two-wavelength WDM analog CATV transmission system which utilizes wavelength channel spacing of about 2.2 nm and laser-dithering. The system includes a pair of optical transmitters (DBF lasers), a pair of modulators, a dithering device, a polarization controller, a 3-dB combiner, an optical amplifier (EDFA), an attenuator, a length of optical fiber, a filter and a CATV receiver. The two lasers have wavelengths of .lambda.1 and .lambda.2, where the difference between .lambda.1 and .lambda.2 is approximately 2.2 nm. The modulators are driven with analog signals comprising 77 NTSC channels between 55.25 and 535.25 MHz A 2-GHz dithering tone is applied to the .lambda.1 laser and the output of the .lambda.2 laser is passed through the polarization controller to align the polarization of the two transmitters. The two modulated and aligned outputs are combined by the 3-dB combiner and launched into the EDFA The output of the EDFA is divided by the splitter four ways and one of the four outputs is passed through the attenuator and launched into the transmitting end of the optical fiber. The receiving end of the fiber is connected to a filter, which provides input into the CATV receiver. By utilizing a wavelength channel spacing of about 2.2 nm and dithering one of the lasers, worst-channel Composite Triple Beat distortion is reduced to -60 dBc, an acceptable level for deployment of WDM analog CATV systems.

Two-wavelength WDM Analog CATV transmission with low crosstalk

A method and apparatus for substantially reducing OBI on optical networks in which a number of source lasers operate simultaneously and the output from the lasers is subsequently combined in the network. The method involves operating the laser in burst mode such that the laser is operational only during transmission periods.

Broadband communications method and apparatus for reducing optical beat

Apparatus and methods for improving linearity and noise performance of

An optical demultiplexing apparatus is capable of spatially separating a multiplexed optical signal into two or more optical wavelength signals thereof. An input multiplexed optical signal present on a first plane is imaged through a color-selective grating plane to a second plane. The color-selective grating has a nonlinear change of diffraction characteristics as a function of incident wavelength to provide substantial spatial separation in the second plane between bands of wavelengths proximate to the two or more optical wavelength signals. In another embodiment, the apparatus uses a polarization-selective grating to spatially separate a polarization-multiplexed optical signal into two substantial spatially separated optical polarization signals. In other embodiments, the optical apparatus may be used as an optical signal multiplexer, splitter, or combiner.

Multiple-wavelength optical transceiver

A passive optical network for the downstream dense wavelength division multiplexing communication of data between a host terminal complex (HTC) and a plurality of optical network units (ONUs), and for the upstream communication of data from the ONUs to the HTC. The network includes a routing device for distributing downstream data signals contained in a common frequency band among a plurality of fiber drop lines for providing a corresponding wavelength to a corresponding ONU. The routing device also combines upstream data signals contained in a frequency band other than the downstream common frequency band, which are input to the routing device on the plurality of fiber drop lines, to a multi-wavelength signal which is provided to the HTC. In a preferred embodiment, the upstream data signals are output by the routing device to a broadcast port.

Growing community of inventors

Holmdel, NJ, United States of America

Thomas Huntington Wood