Abstract: A Re-Configurable Dispersion Compensation Module is provided. A new approach to the variable DCM, the RDCM combines existing optical switch technology with existing fixed DCM technology and advantageously also with existing TDCM technology into a programmable smart optical component. Advantageously Micro-Electrical Mechanical Switch (MEMS) optical switch technology may be used. The alternate RDCM technology provides a controller, and a set of controllable switches to employ a set of DCMs and TDCMs for adjusting the dispersion compensation along an optical signal path. This alternate RDCM technology mitigates the problems of conventional TDCMs, while fitting most of the requirements for high speed systems, and being of a compact size.

Abstract: Systems and methods for providing compact dispersion compensation modules. In one implementation, a dispersion compensation module includes a polarizer having a first port, a second port, and a third port. The dispersion compensation module also includes a reflection etalon and a quarter-waveplate positioned between the reflection etalon and the second port of the polarizer.

Abstract: Systems and methods for optical communications. In one implementation, a communications device is provided. The communications device includes an Optical domain Adaptive Dispersion Compensation Module (OADCM); an Electrical domain Adaptive Distortion Compensation Module (EADCM); and a controller coupled to, and operable to selectively control, both the OADCM and the EADCM.

Abstract: An apparatus is provided comprising a dual optical amplifier. The two optical amplifiers are integrated, in that they share at a set of optical, electrical, or opto-electrical components. The two optical amplifiers may share a pump laser. Alternatively, the optical amplifiers may share photo-detectors. Methods of controlling the signal strength of output signals are also provided. A chip-based integrated optical dual amplifier, using Erbium-Doped Waveguides, is also provided.

Abstract: A Re-Configurable Dispersion Compensation Module is provided. A new approach to the variable DCM, the RDCM combines existing optical switch technology with existing fixed DCM technology and advantageously also with existing TDCM technology into a programmable smart optical component. Advantageously Micro-Electrical Mechanical Switch (MEMS) optical switch technology may be used. The alternate RDCM technology provides a controller, and a set of controllable switches to employ a set of DCMs and TDCMs for adjusting the dispersion compensation along an optical signal path. This alternate RDCM technology mitigates the problems of conventional TDCMs, while fitting most of the requirements for high speed systems, and being of a compact size.

Abstract: A novel integrated multiple-rate optical time division multiplexing (OTDM) module is disclosed. An integrated set of modulators generates optical RZ signal streams which are then time-delayed by a set of integrated optical delay switching and combining arrays and interleaved to produce an OTDM signal. The integrated optical delay switching and combining arrays are adapted to be controllably set to various delays to facilitate interleaving of many possible bit-rates. Such an approach alleviates stability problems offered by conventional fiber-based OTDM technology, increases flexibility, aids in reducing the size, complexity, and cost. Furthermore, the OTDM chip of the present invention offers fine tuning capabilities thereby allowing for slight adjustments in the interleaving of optical signal streams if needed. The present invention also provides for the integration of an optical pulse source chip and a multiple-rate OTDM chip onto a single substrate or platform using hybrid packaging technology.

Abstract: According to the invention there is provided a method of controlling an optical communication system comprising an optical transmitter, an optical receiver and an optical fiber interconnecting the optical transmitter and the optical receiver, the method comprising determining the performance of the optical communication system and controlling at least one setting parameter of the optical transmitter according to the measured performance.

Abstract: A tuning system for use in a receiver of an optical transmission system. The receiver includes a data channel transporting a data signal and a monitoring channel transporting a copy of the data signal. The tuning system includes a processing module for processing the copy of the data signal to generate a control signal conveying tuning information. This tuning information is used by the receiver to alter an operating point of the receiver on the data channel. The operating point of the receiver that is susceptible to be altered by the control signal is a decision threshold applied on the data signal to discriminate one binary value from another binary value on the data channel of the receiver. This approach allows, when required or desired, tuning of the system while the system is in service. This is possible since the tuning of the system is performed using the monitoring channel, and does not disturb nor corrupt the actual data being transported on the data channel.

Abstract: A method and an apparatus for implementing carrier suppressed data format on conventional OTDM modules is provided. Adaptive phase shifting of optical signals traversing one of the tributaries of an OTDM module is performed with feedback loop control. A tapped portion of the input carrier signal is phase modulated at a frequency fc, and is combined with a tapped portion of the output from the OTDM. A phase shifter controller fed with this combined signal photodetects and band-pass filters the signal around fc to extract the amplitude of the AC component of the envelope of the combined signal, which depends upon the phase difference between successive pulses of the OTDM output. This signal is used to control a phase shifter coupled along one of the tributaries of the OTDM to adjust the phase difference of the signals of the two tributaries so that carrier suppression results.

Abstract: A novel optical time division multiplexing (OTDM) module based on hybrid-integrated optical chips is disclosed. An integrated modulator chip generates optical RZ signal streams which are then interleaved in an integrated time-delay chip to produce an OTDM signal. The integrated modulator chip is coupled and secured to the integrated time-delay chip via a suitable optical index-matching layer or collimating lenses. Such an approach alleviates the stability problems offered by conventional fiber-based OTDM technology and aids in reducing the size and complexity as well as lowering the cost for the assembly. Furthermore, the time-delay chip of the present invention offers fine tuning capabilities thereby allowing for slight adjustments in the interleaving of optical signal streams when non-standard data transmission rates are required.

Abstract: A multi-purpose bit error rate tester (MPBERT) and a method of bit error rate (BER) testing of electrical and optical components and subsystems of electrical and optical communications systems is provided. The invention provides for bit error rate testing both in the optical and the electrical domain, and for bit error rate testing at higher than achievable rates in the electrical domain by multiplexing and demultiplexing in the optical domain. An MPBERT constructed according to the invention incorporates at least one optical multiplexer, and advantageously incorporates at least one optical demultiplexer, and in some embodiments uses high data rate optical RZ to NRZ conversion and high data rate optical NRZ to RZ conversion.

Abstract: A method of channel balance for a channel balance section in an WDM optical network with a starting node, an ending node and a plurality of intermediate OADNs (Optical Add Drop Node) first determines express wavelengths and non-express wavelengths starting from the starting node, then calculates TX (transmitter) power change which will bring the express channel performance to a target value and sets TX power using obtained TX power value. The method then moves to non-express channels by calculating TX power change for each non-express channel and sets TX power using obtained TX power value. Lastly, for each intermediate OADN, the method calculates TX power change for each added channel in each OADN and sets TX power using obtained TX power value.

Abstract: An apparatus for measuring the optical-signal-to-noise ratio (OSNR) of an optical system is adapted to function in single channel or in multi-channel wavelength division multiplexed optical communication systems. An optical signal spectrum and a center frequency characterize the optical signals. A narrow-band notch filter, realized by an in-fiber Bragg grating, is utilized to remove a component of the signal so the remaining signal can be measured. When multiple channels are present, a bandpass filter is used to select the part of the multiplexed signal to be measured. Both the narrow-band notch filter and the bandpass filter can be tunable to further extend the capabilities of the system. Two detectors are utilized with the power in the channel being measured by a low-gain detector and the power in the noise being measured by a high-gain detector. A processor receives the detector outputs, calculates OSNR, and controls the tunable components.

Abstract: An in-line repeater implemented within a Wavelength Division Multiplexed (WDM) optical fiber communication system is shown that includes an attenuator. The communication system includes a WDM multiplexer that transmits a WDM signal including a series of WDM channels, via the in-line repeater, to a demultiplexer that separates the WDM channels into a series of output signals. Within the in-line repeater, the attenuator is coupled between two stages of a single amplifier in order to aid in the power equalization of the WDM channels at the demultiplexer. The addition of the attenuator results in the powers and OSNR of the individual WDM channels becoming closer in value, hence reducing the time and the dynamic range of transmitter power adjustments required for traditional methods to equalize the channels' powers.

Abstract: An optical filter is provided having first and second graded index (GRIN) lenses preferably disposed in a coaxial relationship so that they have a common optical axis. Each of the GRIN lenses has an end face providing a port at predetermined location. The ports are disposed on opposite sides of the optical axis and each of the ports is substantially equidistant from the optical axis, so as to be oppositely offset from the optical axis by a same amount. The filter also includes an optical interference filter disposed between other end faces of the first and second graded index lenses. By providing at least four spaced ports, equidistant from the optical axis, such that two ports form a first couplet on opposite sides of the axis from each other and such that two other ports form a second couplet on opposite sides of the axis from each other, wherein one of the ports of one couplet is optically coupled with one of the ports from the other couplet, an add and drop circuit may be realized.

Abstract: An optical device simultaneously provides a multiplexing and demultiplexing function and combines dichroic WDM filter technology with Bragg grating filter technology. A plurality of adjacent sequential ports of a multi-port optical circulator serve as a vehicle for launching and receiving a multi-wavelength optical signal to be separated by the Bragg and dichroic filters. Other adjacent sequential ports having similar filters tuned to different wavelengths provide paths for combining the other wavelengths of light into a single signal. Conveniently a single circulating port serves as the input/output port of the device. The configuration can be applied an optical waveguide structure and, or more particularly to an optical fiber structure. Furthermore this configuration can combine multiplexing/demultiplexing function with a dispersion compensation function by adding a group of fiber Bragg gratings to a port of a circulator.

Abstract: A system for modifying an input optical signal by reducing its bandwidth and modifying its central wavelength has an optical circulator with at least three ports and at least two optical filters coupled to consecutive ports of the circulator. The first filter produces a predetermined reflected band off the input optical signal. The second filter produces a predetermined transmission band as a part of the reflected band. Either or both of the optical filters are tunable to shape and trim the input signal in a predetermined manner. A multi-channel and cascade configurations may be formed. The system may serve e.g. as a tunable filter or as an add/drop module in WDM communication networks.

Abstract: Bidirectional WDM transmission at 2.5 Gb/s using a bidirectional erbium-doped fiber amplifier (EDFA) is demonstrated over a distance of 300 km. A symmetrical EDFA configuration with a frequency tunable reflection attenuator is used as a bidirectional amplifier. Experimental results show that the allowable gain of the EDFA can be increased significantly while the associated bit error rate BER penalty remains negligible.

Abstract: A device for distributing an optical signal has an optical waveguide with a plurality of gratings disposed in series therein, the gratings having a predetermined reflectivity response within a specific wavelength range; an optical circulator having at least three ports, one of the ports serving as an input port for receiving the optical signal, and another port for removing at least a part of the optical signal reflected from one of the gratings; and control means for individually controlling at least some of the gratings to effect a change of the wavelength range of the reflectivity response of the gratings. The change may be a shift, an expansion or a compression of the range. The device can function as a signal distributor (router), an equalizer or a demultiplexer. The reflectivity response is preferably a sloped response.