Abstract: A method and system for measuring physical parameters using sensors of the birefringent Fiber Bragg Grating type is provided. In some embodiments, a method and a system for querying a sensor of the birefringent Fiber Bragg Grating (FBG) type (e.g., in birefringent fiber), employing heterodyne optical detection and integrated photonic technology is provided.

Abstract: A method for interrogating an FBG sensor includes lighting the FBG sensor with a broadband excitation optical radiation, conveying the optical spectrum transmitted or reflected by the FBG sensor to a tunable optical BPF having a first extraction port and a second transmission port, tuning the optical BPF at a constant operating wavelength, depending on nominal operating wavelength of the FBG sensor, detecting a first optical signal exiting the first extraction port, converting, by a first opto-electronic receiver, the first optical signal into a first electrical signal, representative of a wavelength shift of the spectrum transmitted or reflected by the FBG sensor, detecting a second optical signal exiting the second transmission port, converting the second optical signal, by a second opto-electronic receiver, into a second electrical signal, representative of an optical reference power, and determining the wavelength shift of the spectrum transmitted or reflected by FBG sensor, based on detected first and se

Abstract: A method for measuring a distributed physical value of an optical device under test (DUT), includes the steps of: launching into the DUT a probe signal that includes a plurality of optical pulses at at least one test wavelength, and receiving at least one optical signal backscattered by the DUT, wherein the optical pulses are obtained with at least the following steps: generating a first time sequence of first pulses that corresponds to a word of a first code, the first time sequence lasting not shorter than a time of flight and being formed by a number of time slots that is equal to the number of bits of the word of the first code; generating a second time sequence of second pulses that corresponds to a word of a second code; and amplitude modulating the second time sequence with the first time sequence.

Abstract: A method for measuring a distributed physical value of an optical device under test (DUT), includes the steps of: launching into the DUT a probe signal that includes a plurality of optical pulses at at least one test wavelength, and receiving at least one optical signal backscattered by the DUT, wherein the optical pulses are obtained with at least the following steps: generating a first time sequence of first pulses that corresponds to a word of a first code, the first time sequence lasting not shorter than a time of flight and being formed by a number of time slots that is equal to the number of bits of the word of the first code; generating a second time sequence of second pulses that corresponds to a word of a second code; and amplitude modulating the second time sequence with the first time sequence.

Abstract: Optical add and drop switch and aggregator apparatus comprising: N first wavelength selective routing apparatus each configured to split a wavelength multiplexed input signal into L sub-signals; demultiplexers each configured to demultiplex a respective sub-signal into K optical signals; output ports each configured to output a respective output optical signal; add ports configured to receive optical signals to be added; M second wavelength selective routing apparatus each having X outputs, each said apparatus being configured to receive optical signals from a respective add port and to route each received optical signal to a respective one of its outputs; drop ports configured to output optical signals to be dropped; and a switch matrix coupled between the demultiplexers, the output ports, the drop ports and the second wavelength selective routing apparatus, the switch matrix comprising a plurality of optical switches arranged in XM columns and KLN rows.

Abstract: Optical add and drop switch and aggregator apparatus comprising: N first wavelength selective routing apparatus each configured to split a wavelength multiplexed input signal into L sub-signals; demultiplexers each configured to demultiplex a respective sub-signal into K optical signals; output ports each configured to output a respective output optical signal; add ports configured to receive optical signals to be added; M second wavelength selective routing apparatus each having X outputs, each said apparatus being configured to receive optical signals from a respective add port and to route each received optical signal to a respective one of its outputs; drop ports configured to output optical signals to be dropped; and a switch matrix coupled between the demultiplexers, the output ports, the drop ports and the second wavelength selective routing apparatus, the switch matrix comprising a plurality of optical switches arranged in XM columns and KLN rows.

Abstract: A Raman amplifier structure (121, 221) for optically amplifying an input optical signal comprises an optical means (22) through which the optical signal is propagated, a first pump optical source (10) for generating a first pump radiation and at least one second pump optical source (24, 27) for generating a second pump radiation. The first and second pump optical radiations are combined and propagated in optical transmission means (22) for supplying an optical amplification of the signal through the Raman effect. The first pump optical source (10) comprises a first laser source (12) for generating a radiation with relatively low noise and relatively low power and a Raman amplifier (13) for amplifying the radiation coming from the first laser source for generating the first pump radiation.

Abstract: A looped WDM optical network comprises an optical loop with optical amplifiers (12,16) between the sections of the loop (11) and with ASE recirculation in the loop. At a point of the loop a laser beam is injected and allowed to circulate in the loop with the laser beam being centered around a ?LINK wavelength where it is desired that a lasing peak be generated. This supplies high network strength in terms of section loss variations and greatly improves the OSNR of the WDM signal. High network survivability is also achievable.

Abstract: A Raman pump module for generating pump radiation having a pump wavelength (?p) for coupling into a transmission fiber of an optical wavelength division multiplex (WDM) communication system to provide Raman amplification of WDM radiation counter propagating therethrough is disclosed. The pump module is for use in a communications system in which the WDM radiation has a transmission waveband (?s) and wherein the transmission fiber has a zero dispersion wavelength (?m) lying midway between the transmission waveband and the pump wavelength. The module comprises a Raman pump laser for generating the pump radiation and a de-correlator for de-correlating the longitudinal modes of the pump radiation before it is coupled into the transmission fiber.

Abstract: An adaptive dispersion compensation system that also achieves optical amplification by inducing Raman amplification effects in dispersion compensating fiber. This amplification/chromatic dispersion compensation architecture may be applied, e.g., at the end of an all-optical link, or an intermediate points along the link. By varying the length of dispersion compensating fiber used and the pump power, one may accommodate a wide range of dispersion compensation requirements as determined in the field. This scheme also provides all of the advantages typically provided by the use of Raman amplification.

Abstract: A looped WDM optical network comprises an optical loop with optical amplifiers (12,16) between the sections of the loop (11) and with ASE recirculation in the loop. At a point of the loop a laser beam is injected and allowed to circulate in the loop with the laser beam being centered around a ?LINK wavelength where it is desired that a lasing peak be generated. This supplies high network strength in terms of section loss variations and greatly improves the OSNR of the WDM signal. High network survivability is also achievable.

Abstract: An adaptive dispersion compensation system that also achieves optical amplification by inducing Raman amplification effects in dispersion compensating fiber. This amplification/chromatic dispersion compensation architecture may be applied, e.g., at the end of an all-optical link, or an intermediate points along the link. By varying the length of dispersion compensating fiber used and the pump power, one may accommodate a wide range of dispersion compensation requirements as determined in the field. This scheme also provides all of the advantages typically provided by the use of Raman amplification.

Abstract: An adaptive dispersion compensation system that also achieves optical amplification by inducing Raman amplification effects in dispersion compensating fiber. This amplification/chromatic dispersion compensation architecture may be applied, e.g., at the end of an all-optical link, or an intermediate points along the link. By varying the length of dispersion compensating fiber used and the pump power, one may accommodate a wide range of dispersion compensation requirements as determined in the field. This scheme also provides all of the advantages typically provided by the use of Raman amplification.

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: Raman amplification of a WDM signal with excellent gain flatness across a very large bandwidth is achieved. Co-propagating and counter-propagating Raman pumping are combined in the same fiber. Multiple pumping wavelengths are employed. Wavelengths employed for co-propagating pumping and wavelengths employed for counter-propagating pumping alternate in order of wavelength. In one embodiment, N co-propagating pump wavelengths and N+1 counter-propagating pump wavelengths are used. Alternatively, one may use N+1 co-propagating pump wavelengths and N counter-propagating pump wavelengths.

Abstract: Systems and methods for ameliorating double Rayleigh backscattering induced impairments are provided. Raman amplification is divided among two or more stages. Optical energy from a single counter-propagating pump may traverse multiple stages while optical energy at the frequency of the signal to be amplified is permitted to propagate in the forward direction only. In this way the pump power can be effectively distributed over the entire amplifier length. The scheme may be implemented in a simple configuration employing a closed circulator and a fiber Bragg grating. Multiple wavelength pump operation may be accommodated as well as either discrete or distributed Raman amplification.

Abstract: An adaptive dispersion compensation system that also achieves optical amplification by inducing Raman amplification effects in dispersion compensating fiber. This amplification/chromatic dispersion compensation architecture may be applied, e.g., at the end of an all-optical link, or an intermediate points along the link. By varying the length of dispersion compensating fiber used and the pump power, one may accommodate a wide range of dispersion compensation requirements as determined in the field. This scheme also provides all of the advantages typically provided by the use of Raman amplification.

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.

Abstract: Four-wave mixing crosstalk between co-propagating Raman amplification pump sources and WDM channels is suppressed. Therefore, co-propagating pumping may be applied to Raman amplification without incurring penalties due to four-wave mixing crosstalk. Pump power need not be substantially increased to accommodate use of the present invention. Also, the use of lower cost Fabry-Perot pump sources is facilitated. In one implementation, the advantageous suppression of four-wave mixing crosstalk between pump signals and WDM channels is accomplished by imposing chromatic dispersion on the co-propagating pump sources.

Abstract: An advantageous amplification architecture for DWDM systems including systems with very high capacity is provided. A modular interleaved structure for amplification is provided. Advantages include robustness to non-linear effects, modular as-needed deployment of system capacity, and low noise figure in implementations that incorporate Raman amplification technology.