Abstract: An optical amplifier (1), and a related optical amplification method, comprising an optical path (2) having an input end (3) and an output end (4), a first erbium doped optical fiber (5) placed along the optical path, a first gain flatting filter (6) placed along the optical path downstream the first erbium doped optical fiber, a second erbium doped optical fiber (7) placed along the optical path downstream the first gain flatting filter, a second gain flatting filter (8) placed along the optical path downstream the second erbium doped optical fiber, a third erbium doped optical fiber (9) placed along the optical path downstream the second gain flatting filter, and an optical pump (10) optically coupled to the optical path so as to optically pump at least the first and the third erbium doped optical fiber.

Abstract: An optical amplifier (1), and a related optical amplification method, comprising an optical path (2) having an input end (3) and an output end (4), a first erbium doped optical fiber (5) placed along the optical path, a first gain flatting filter (6) placed along the optical path downstream the first erbium doped optical fiber, a second erbium doped optical fiber (7) placed along the optical path downstream the first gain flatting filter, a second gain flatting filter (8) placed along the optical path downstream the second erbium doped optical fiber, a third erbium doped optical fiber (9) placed along the optical path downstream the second gain flatting filter, and an optical pump (10) optically coupled to the optical path so as to optically pump at least the first and the third erbium doped optical fiber.

Abstract: Optical amplification stage (1) for OTDR monitoring, comprising a first (2a) and a second optical signal path (2b), a first (3a) and a second optical amplifier (3b), a first optical coupler (4a) placed along the first optical signal path downstream the first optical amplifier, a second optical coupler (4b) placed along the second optical signal path downstream the second optical amplifier, an optical by-pass path (5) optically connecting the first and the second optical coupler, a first (11a) and a second optical reflector (11b) optically connected to respectively the first and second optical coupler, and an optical filter (10) placed along the optical by-pass path which has attenuation high on the whole WDM band and low at the OTDR wavelength(s).

Abstract: Optical amplification stage (1) for OTDR monitoring, comprising a first (2a) and a second optical signal path (2b), a first (3a) and a second optical amplifier (3b), a first optical coupler (4a) placed along the first optical signal path downstream the first optical amplifier, a second optical coupler (4b) placed along the second optical signal path downstream the second optical amplifier, an optical by-pass path (5) optically connecting the first and the second optical coupler, a first (11a) and a second optical reflector (11b) optically connected to respectively the first and second optical coupler, and an optical filter (10) placed along the optical by-pass path which has attenuation high on the whole WDM band and low at the OTDR wavelength(s).

Abstract: A method for integrating an Optical Service Channel (OSC) with a Quantum Key Distribution (QKD) channel across a DWDM network having a single mode optical fiber is provided. An optical signal is received. An OSC is coupled with the optical signal. A QKD channel is integrated with the OSC on the single mode optical fiber.

Abstract: Agile OADM structures having a range of tradeoffs between costs and flexibility are disclosed. In certain implementations, cyclic AWGs (arrayed waveguide gratings) are employed. Excellent optical performance is achieved along with relatively low initial and upgrade costs. An economically optimal level of network flexibility may thus be achieved.

Abstract: Improved lumped Raman amplification systems are disclosed. A lumped Raman amplification structure provides optimized efficiency, low noise figure over a range of gain settings, and a high saturation threshold. Responsibility for amplifying different portions of the spectrum is divided among multiple stages. In one particular implementation, two outer stages amplify a first band and two inner stages amplify a second band. The two inner stages also apply a small amount of amplification to the first band. A modification improves noise figure in the second band by adding some amplification in the second band to the first stage.

Abstract: Agile OADM structures having a range of tradeoffs between costs and flexibility are disclosed. In certain implementations, cyclic AWGs (arrayed waveguide gratings) are employed. Excellent optical performance is achieved along with relatively low initial and upgrade costs. An economically optimal level of network flexibility may thus be achieved.

Abstract: Systems and methods for evaluating an optical communication link are provided. The evaluation is based on a polarization analysis of received optical power. Such an analysis is able to differentiate between received noise and received optical signal power, even for typical multi-channel signals. By appropriately analyzing the polarization of received optical power, the link quality can be evaluated. Failures may be detected and optical signal to noise ratio may be measured.

Abstract: Optical connection verification schemes that do not cause electromagnetic interference. An all-optical connection verification scheme exploits optical coding based on a standard color scale such as RGB (red, green, blue). An RGB LED source is used to launch a three-color optical signal where the relative (or absolute) magnitudes of the color components identify the connection. On the receiver end, an RGB photodiode measures the relative (or absolute) magnitudes of the color components to verify the connection. Alternatively, one end of the connection may transmit white light with the other end reflecting back a similar three-color signal by use of a color-coded panel reflector.

Abstract: A method for integrating an Optical Service Channel (OSC) with a Quantum Key Distribution (QKD) channel across a DWDM network having a single mode optical fiber is provided. An optical signal is received. An OSC is coupled with the optical signal. A QKD channel is integrated with the OSC on the single mode optical fiber.

Abstract: Agile OADM structures having a range of tradeoffs between costs and flexibility are disclosed. In certain implementations, cyclic AWGs (arrayed waveguide gratings) are employed. Excellent optical performance is achieved along with relatively low initial and upgrade costs. An economically optimal level of network flexibility may thus be achieved.

Abstract: Improved lumped Raman amplification systems are disclosed. A lumped Raman amplification structure provides optimized efficiency, low noise figure over a range of gain settings, and a high saturation threshold. Responsibility for amplifying different portions of the spectrum is divided among multiple stages. In one particular implementation, two outer stages amplify a first band and two inner stages amplify a second band. The two inner stages also apply a small amount of amplification to the first band. A modification improves noise figure in the second band by adding some amplification in the second band to the first stage.

Abstract: An amplifier including a first input for a first at least two input signals having mutually distinct wavelengths, a first output for a first at least two output signals, the first at least two output signals having said mutually distinct wavelengths, a first circulator including an input port coupled to the first input, an output port coupled to the first output, and an intermediate port coupled to a first end of a selective reflection circuit, and, a second circulator including an intermediate port coupled to a second end of the selective reflection circuit, an output port coupled to a first selective splitter, and an input port coupled to a second selective splitter, wherein the first selective splitter and the second selective splitter are centered about a first selected wavelength amongst the mutually distinct wavelengths.

Abstract: An amplification architecture for WDM receiver systems. The WDM channel grid is divided into groups of adjacent channels. A separate optical amplifier is provided for each channel with a single pump being shared among the channels of each group. The gain experienced by channels of a given group may be adjusted by varying the power of the group's pump. This approach allows equalization of received channel power such that all channels fall within the desired dynamic range. The amplification architecture may be implemented in a space-efficient manner at low cost.

Abstract: An approach for automatic Raman gain and tilt control for a WDM (Wavelength Division Multiplexing) optical communication systems is disclosed. An optical fiber carries a plurality of optical signals, in which at least one of the optical signals are reference signals. An optical gain unit (e.g., Raman pump unit) couples to the optical fiber and adjusts the reference signals to compensate, in part, for losses associated with the optical fiber and gain tilt accumulation. Upon detecting and analyzing the reference signals, a controller controls the optical gain unit and outputs a control signal to the optical gain unit based upon the analyzed reference signals. An optical amplifier is connected to the optical fiber and amplifies the optical signals. The optical gain unit provides a nearly constant power per channel at an input of the optical amplifier.

Abstract: An amplifier including a first input for a first at least two input signals having mutually distinct wavelengths, a first output for a first at least two output signals, the first at least two output signals having said mutually distinct wavelengths, a first circulator including an input port coupled to the first input, an output port coupled to the first output, and an intermediate port coupled to a first end of a selective reflection circuit, and, a second circulator including an intermediate port coupled to a second end of the selective reflection circuit, an output port coupled to a first selective splitter, and an input port coupled to a second selective splitter, wherein the first selective splitter and the second selective splitter are centered about a first selected wavelength amongst the mutually distinct wavelengths.

Abstract: An amplification architecture for WDM receiver systems. The WDM channel grid is divided into groups of adjacent channels. A separate optical amplifier is provided for each channel with a single pump being shared among the channels of each group. The gain experienced by channels of a given group may be adjusted by varying the power of the group's pump. This approach allows equalization of received channel power such that all channels fall within the desired dynamic range. The amplification architecture may be implemented in a space-efficient manner at low cost.

Abstract: An amplifier including a first input for a first at least two input signals having mutually distinct wavelengths, a first output for a first at least two output signals, the first at least two output signals having said mutually distinct wavelengths, a first circulator including an input port coupled to the first input, an output port coupled to the first output, and an intermediate port coupled to a first end of a selective reflection circuit, and, a second circulator including an intermediate port coupled to a second end of the selective reflection circuit, an output port coupled to a first selective splitter, and an input port coupled to a second selective splitter, wherein the first selective splitter and the second selective splitter are centered about a first selected wavelength amongst the mutually distinct wavelengths.

Abstract: A modular interleaved Raman amplifier structure is exploited to reap the advantages provided by the high Raman gain coefficient and small effective area of highly nonlinear fibers without incurring penalties caused by nonlinear effects and double-Rayleigh backscattering noise. Very tight WDM channel spacings may be accommodated. The amplifier structure may be implemented at very low initial cost and with high reliability, scalability, and modularity.