Techniques, apparatus and systems for optical WDM communications that use spectrally efficient parallel optical WDM channels for WAN and MAN networks.

Spectrally efficient parallel optical wdm channels for long-haul man and wan optical networks

An optical processing method includes: receiving an optical signal from an optical system, wherein the optical signal is distorted by frequency-dependent polarization effects in the optical system; spatially dispersing frequency components of the distorted optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM to reduce the distortion of the optical signal. A related optical processing method includes: providing a precompensation signal indicative of frequency-dependent polarization effects in a downstream optical system; spatially dispersing frequency components of an optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM to at least partially precompensate the optical signal for distortions caused by the frequency-dependent polarization effects in the downstream optical system. Another related optical processing method includes: providing a model of the frequency-dependent polarization effects; spatially dispersing frequency components of the optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM based on the model to emulate the optical signal transmission.

Methods and systems for polarization control and polarization mode dispersion compensation for wideband optical signals

The present invention relates to an automatic dispersion compensating optical link system. Carrier suppressed RZ encoded optical signals generated using carrier suppressing means and binary NRZ code or partial response code, or carrier suppressed clock signals generated using carrier suppressing means and clock signals are transmitted on an optical transmission line. Two bands of the carrier suppressed RZ encoded optical signals or carrier suppressed clock signals transmitted on the optical transmission line are each divided into bands and are received. Phase information of the respective basebands is extracted from the binary NRZ code components or partial response code components or clock signals in each band and the relative phase difference thereof is detected. The chromatic dispersion value of the optical transmission line is then calculated from the relative phase difference.

High precision chromatic dispersion measuring method and automatic dispersion compensating optical link system that uses this method

Cost-reduction in an optical communication unit is achieved by using spectrum-sliced modulated broadband light for transmitting upstream signals, instead of using laser light. An optical communication system includes at least one pair of optical communication units that each has a bi-directional network interface in which physical bit rates of transmission signals and reception signals are identical, an optical transmitter, and an optical receiver, and that performs bi-directional transmissions via at least one optical fiber. One optical communication unit includes a physical bit rate down-converter that lowers the physical bit rate of transmission signals from the bi-directional network interface and outputs to the optical transmitter, and the other optical communication unit includes a physical bit rate up-converter that raises the physical bit rate of signals received by the optical receiver and outputs to the bi-directional network interface. These optical communication units are also applicable to wavelength-division multiplexing systems.

Optical communication system, optical communication unit, and optical transceiving package

Integrated and stand-alone methods and apparatus for adaptively compensating for DGD, SOPMD, and CD in optical communication networks are provided. One apparatus includes at least three optical compensators that are optically coupled together in series and a feedback controller. Each compensator includes a variable optical controller that is optically coupled in series to a birefringent element. An optical communication network is also provided that at least includes an optical transmission line, at least two network terminals, and at least one static compensation module. At least one terminal includes an optical demultiplexer that is coupled to that element, a plurality of λ-compensators, and, optionally, a static optical dispersion compensation element.

Methods and apparatus for compensating chromatic and polarization mode dispersion

The present invention offers a polarization mode dispersion compensator and a compensation method for polarization mode dispersion having simple constitution and being strong against external disturbances. The polarization mode dispersion compensator, a representative example of the present invention, is provided with a compensation circuit for polarization mode dispersion, a degree of polarization measuring circuit, and a control circuit. An optical signal is input to the compensation circuit for polarization mode dispersion through an optical fiber, and after the process of compensation for polarization mode dispersion, it is output to an optical fiber. An optical coupler divides a part of the optical signal passing through the optical fiber. The degree of polarization measuring circuit finds the degree of polarization of the divided optical signal. The control circuit generates a control signal based on the degree of polarization obtained in the above, and so controls the compensation circuit for polarization mode dispersion as to make the degree of polarization maximum.

Polarization mode dispersion compensator and compensation method

The technical problem disclosed concerns increase of transmission distance between inter-site transmission parts when a circuit speed is increased, and simplification of an intra-site circuit. According to the present invention, an intra-site circuit connecting an intra-site information communications device and a wavelength division multiplexing optical transmission device is demultiplexed into plural low speed wavelength division multiplexing signals by a transponder according to this invention, and transmitted to an inter-site optical fiber circuit. The signals are again multiplexed into a high-speed optical signal by a transponder in a wavelength division multiplexing optical transmission device on the receiving side, and transmitted to an intra-site optical fiber circuit.

Equipments, transpondor and methods for optical fiber transmission

A transponder which may form part of communication device such as an optical transmitters device includes an optical receiver for receiving a high speed optical information signal and for converting the high speed optical information signal to an electrical signal, a demultiplexing circuit for separating the electrical signal into a plurality of low speed information signals, a plurality of optical transmitters each of which converts one of the low speed electrical signals into an optical signal of mutually different wavelengths, and a propagation delay difference compensating circuit. The propagation delay difference compensating circuit is provided between the demultiplexing circuit and the plurality of optical transmitters and compensates mutual propagation delay differences of each of the optical signals outputted from the optical transmitters.

Equipments including transponder for optical fiber transmission

PROBLEM TO BE SOLVED: To increase the range of an inter-station transmission or to simplify an inter-station line when the line speed is increased. SOLUTION: A transponder 100 separates an intra-station line connecting intra-station information communication equipment 140-1 and a wavelength multiplex light transmission device 147 into plural low speed wavelength multiplex signals and transmits them through an inter-station optical fiber line 144. A transponder 110 in the wavelength multiplex light transmission device 148 of a reception side 148 multiplexes them again into high speed light signals and transmits them through an intra-station optical fiber line 143-1. Since the transmission speed of the intra-station line can be speeded up irrespective of the transmission speed of an inter-station wavelength multiplex signal, the cost of an intra-station interface part can be reduced and the number of intra- station lines can be reduced.

Wavelength multiplex transmission system and device used for the same

PROBLEM TO BE SOLVED: To provide the system immune to external disturbance regardless of a simple configuration. SOLUTION: This system is provided with a polarized wave dispersion compensation circuit 100, a degree of polarization detection circuit 104 and a control circuit 105. The polarized wave dispersion compensation circuit 100 receives an optical signal through an optical fiber 101, compensates polarized wave dispersion and provides an output to an optical fiber 102. A photocoupler 103 branches part of the optical signal passing through the optical fiber 102 to the degree of polarization detection circuit 104, which obtains a degree of polarization of the branched optical signal. The control circuit 105 generates a control signal 106 based on the degree of polarization that is obtained by the circuit 104 and controls the polarized wave dispersion compensation circuit 100 to maximize the degree of polarization. COPYRIGHT: (C)2000,JPO

Nobuhiko Kikuchi

Papers

Polarization mode dispersion compensator and compensation method

Equipments, transpondor and methods for optical fiber transmission

Equipments including transponder for optical fiber transmission

Wavelength multiplex transmission system and device used for the same

Polarized wave dispersion compensation system and polarized wave dispersion compensation method