Redc Optical Networks Inc.

Finisar Israel Ltd.

Redc Optical Networking Ltd.

Red - C Optical Newworks Ltd.

Edc Optical Networks Inc.

Uri Ghera

David Menashe

Alex Shlifer

Daniel Berger

Reuven Zaibel

Mark Raymond Zaacks

Doron Meshulach

Tomer Eliyahu

Yoav Sintov

Ophir Eyal

Itzhak Filiba

Roberto Klein

Eyal Sarid

Methods for optimizing a noise figure of a variable gain hybrid amplifier (HA) which includes a variable gain Raman amplifier with adjustable average gain Gand gain tilt Tand a variable gain lumped amplifier with adjustable average gain Gand gain tilt T. In various embodiments, the methods include receiving as input a required hybrid amplifier average gain Gvalue and a required gain tilt Tvalue and deriving a set of G, T, Gand Tvalues which yield an optimal optimized hybrid amplifier NF and satisfy the conditions G+G=Gand that T+Tis within a specified hybrid amplifier operating tilt range. In some embodiments, the derived Tand Tvalues satisfy the condition T+T=T.

Hybrid optical amplifier with optimized noise figure

Apparatus and method for gain measurement and control of a Distributed Raman Amplifier (DRA). Various embodiments of the apparatus include a detection unit operative to measure, during operation of the DRA, the optical power of a filtered component of the light entering the DRA from the transmission fiber and a gain calculation and control unit coupled to the detection unit and operative to calculate a signal Raman gain property from the measured optical power. The filtered component may exemplarily be a result of passing the light through a band pass filter, a spectral filter with a given spectral shape or a notch filter. The signal Raman gain property may be an average on-off signal Raman gain, an average net signal Raman gain or a signal Raman gain tilt within a communication band. The apparatus and method may be used to operate the DRA in Automatic Gain Control, i.e. to maintain a required constant signal Raman gain and/or signal Raman gain tilt.

Automatic measurement and gain control of distributed Raman amplifiers

Method and apparatus for detecting an opening in a transmission fiber connecting a discrete gain unit to a pump unit of a Remote Optically Pumped Amplifier (ROPA) system. The method comprises measuring an optical power entering the pump unit from the transmission fiber, the optical power being in a selected wavelength range, and establishing that the optical power lacks an ASE noise power component generated by the gain unit. The lack of this component indicates the presence of a break or opening in the transmission fiber, and triggers corrective action whereby pump lasers within the pump unit are shut down or have their power reduced to a safe level.

Method and apparatus of detecting an opening in an optical transmission fiber of a ROPA system

A method and apparatus for automatic shut-down and start-up of optical amplifiers in wavelength division multiplexed (WDM) optical networks include use of an optical channel monitor (OCM) to monitor loss and return of an input signal. By using the OCM to separately monitor the power level of each individual channel, it is possible to detect loss of all channels or return of a single channel even in the presence of ASE at the amplifier input. The OCM receives a fraction of the input power to the amplifier via an optical tap at the amplifier input, and provides an electrical output to a control unit corresponding to the optical power level of each individual WDM channel. Based on this electrical output, the control sends a shut-down or start-up signal to the pump unit within the amplifier.

Method and apparatus for automatic shut-down and start-up of optical amplifiers in optical networks

A system and method for providing eye-safety protection during operation of a lumped optical amplifier. The method is based on monitoring of continuous out-of-band Raman amplified spontaneous scattering (ASS) created by the amplified signal in an optical communication network span coupled to an output port of the lumped optical amplifier. The system includes at least one gain stage for providing an amplified signal introduced into the span, a monitoring unit for performing the continuous Raman ASS monitoring, and a control unit operative to detect and analyze in real-time changes in the ASS power, and upon determination that such changes indicate an open span, to reduce the power of the amplified signal or shut down the gain stage.

Method and system for improved eye protection safety of high output power lumped optical amplifiers

Efficient wavelength calibration in a WDM optical amplifier that includes an optical channel monitor (OCM) is obtained by introducing a notch into the amplified spontaneous emission (ASE) noise spectrum of the amplifier outside a WDM transmission band, and having the OCM detect the notch and use the notch as a reference to calibrate the wavelength measurement. The notch is introduced into the ASE noise spectrum using a notch filter, which is preferably incorporated in a gain flattening filter (GFF).

Efficient wavelength referencing in a combined optical amplifier-optical channel monitor apparatus

A system and method for providing eye-safety protection during operation of distributed Raman amplifiers based on the application of continuous out-of-band amplified spontaneous scattering (ASS) monitoring in an optical communication network span coupled to the Raman amplifier, and real-time detection and analysis of changes in the monitored ASS power level, The system includes at least one Raman pump for introducing Raman energy into the span, a monitoring unit for performing the continuous ASS monitoring, and a control unit operative to detect and analyze in real-time changes in the ASS power, and upon determination that such changes indicate an open span, to reduce the level of the Raman pump energy entering the span to a safe level.

Method and system for improved eye protection safety of distributed raman amplifiers

Method and system for improved eye protection safety of distributed Raman amplifiers

An apparatus for optical amplification that imparts to a narrow band optical amplifier, specifically an Erbium dope fiber amplifier (EDFA), gain properties found in wide band optical amplifiers. In one preferred embodiment, the apparatus comprises an EDFA and an externally attachable (to the EDFA) module that includes a single un-pumped Erbium doped fiber (EDF) connected to a gain flattening filter (GFF). The GFF may be internal or external to the module. In another embodiment, the apparatus comprises an EDFA and an externally attachable module having a plurality of un-doped EDFs with different lengths, switchably connectable to the GFF and the EDFA to provide the required wide-band gain properties.

Apparatus and method for upgrading a narrow band optical communication system to a system with wide spectral band optical amplification

A high efficiency, high performance optical amplifier includes an amplification stage comprised of two Erbium doped fiber (EDF) gain sections separated by a variable optical attenuator (VOA). A single pump serves to pump both EDF sections. A high dynamic gain range is achieved by an interplay between the action of the VOA, and the pump energy absorption mechanisms in each gain section, which are dominated by the saturation characteristics of each of the EDFs. In a preferred embodiment of the method, input signals are coupled with a pump signal into a first EDF gain section in which the energy absorption mechanisms provide first amplified signals that are correlated with a residual pump signal. At the first EDF gain section output, the combined amplified signals and residual pump signal are decoupled, the amplified signals being attenuated in the VOA while the residual pump signal being routed around the VOA. The attenuated signals and the residual pump signal are recoupled and introduced into the second EDF gain section, in which the energy absorption mechanisms provide gain equalized output signals.

Method and apparatus for a highly efficient, high performance optical amplifier

A method and apparatus for optical amplification with a large dynamic gain range in both the non-linear (1530-1540 nm) and linear (1540-1565 nm) regimes of the C-Band. The large dynamic gain range is achieved by the synergistic operation of a dual-stage Erbium-doped Fiber Amplifier (EDFA) having a self-saturating Thulium-doped fiber inserted between the two stages. The Thulium-doped fiber saturation is determined by the output power of the first EDFA stage, and the synergistic, combined operation of both EDFA stages and the self-saturating absorber is controlled by appropriate algorithms and software.

Method and apparatus for full C-band amplifier with high dynamic gain range

An apparatus and method for a self-adjusting Raman amplifier for fiber optic transmission lines incorporating a line diagnostic mechanism in order to calculate, control and optimize the operating parameters for the amplifier. A Line Analyzing Unit, adjacent to the Raman pump unit, operates before the Raman pump is enabled and during operation, and characterizes the transmission line. The Line Analyzing Unit determines and characterizes the types of optical fibers installed along the transmission line and calculates and optimizes the pump or pumps power in order to achieve optimum gain, gain equalization and gain tilt. The Line Analyzing Unit may also determine if there is an optical loss or reflection in the optical fiber that can be destructive when the high power Raman pump is operating.

Apparatus and method for a self-adjusting Raman amplifier

This invention describes an apparatus and method for a self adjusting Raman amplifier for fiber optic transmission lines incorporating a line diagnostic mechanism in order to calculate, control and optimize the operating parameters for the amplifier. This need arises because the amplifier gain medium is the transmission line itself and the amplifier properties depend on the optical fiber properties along the first tens of kilometers of the transmission line from the pump. A Line Analyzing Unit, adjacent to the Raman pump unit, operates before the Raman pump is enabled and during operation, and characterizes the transmission line. The Line Analyzing Unit determines and characterizes the types of optical fibers installed along the transmission line and calculates and optimizes the pump or pumps power in order to achieve optimum gain and gain equalization. The Line Analyzing Unit may also determine if there is an optical loss or reflection in the optical fiber that can be destructive when the high power Raman pump is operating.

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Tel Aviv, Israel

Uri Ghera