Abstract: This invention relates to a system and method to determine the distributed birefringence profile along an optical fibre. Birefringence manifests as different refractive indices for two orthogonal states of polarization of the light propagating in the optical fibre. The technique is based on the correlation among sets of measurements acquired using phase-sensitive optical time-domain reflectometry (?OTDR), launching light into the fibre with multiple states of polarization. The correlation between the measurements performed while sweeping the laser frequency gives a resonance (correlation) peak at a frequency detuning that is proportional to the refractive index difference between the two orthogonal polarizations. This enables measurements of the local value of the phase birefringence at any position along the optical fibre, so that longitudinal fluctuations of its value can be evaluated.

Abstract: Optic fiber sensor characterized in that the sensing fiber is provided with a continuous Bragg grating covering the entire fiber length which is dedicated to sensing and along which spatially resolved measurements are performed.

Abstract: System and methods for producing a plurality of Sinc shaped pulses in the time domain include a light source for providing an input light signal having an input frequency, and at least one spectrum shaper for producing the plurality of Sinc shaped pulses from the input light signal. The spectrum shaper may include an amplitude modulator, at least one radio-frequency generator and a bias voltage generator.

Abstract: System and methods for producing a plurality of Sinc shaped pulses in the time domain include a light source for providing an input light signal having an input frequency, and at least one spectrum shaper for producing the plurality of Sinc shaped pulses from the input light signal. The spectrum shaper may include an amplitude modulator, at least one radio-frequency generator and a bias voltage generator.

Abstract: Disclosed are methods and devices for distributed sensing of a measurable parameter employing stimulated Brillouin scattering in an optical fiber. A frequency-modulated or phase-modulated light wave is transmitted into the optical fiber. A scattered light wave in the optical fiber is monitored for sensing a measurable parameter. In some embodiments, the calculating step may include calculating a distance of a sensed location along the optical fiber using the monitored time of arrival.

Abstract: Methods of performing a distributing sensing measurement included the steps of, modulating the frequency of one or more light signals output from one or more light sources, using one or more multi-level sequence of bits so that the one or more light signals are frequency modulated; using the one or more frequency modulated light signals to provide a pump signal and a probe signal; propagating the pump and probe signals along an optical fiber; using interactions between the pump and probe signal to perform a distributed sensing measurement. There is further provided corresponding sensing systems.

Abstract: Optic fiber sensor characterized in that the sensing fiber is provided with a continuous Bragg grating covering the entire fiber length which is dedicated to sensing and along which spatially resolved measurements are performed.

Abstract: Disclosed are methods and devices for distributed sensing of a measurable parameter employing stimulated Brillouin scattering in an optical fiber. A frequency-modulated or phase-modulated light wave is transmitted into the optical fiber. A scattered light wave in the optical fiber is monitored for sensing a measurable parameter. In some embodiments, the calculating step may include calculating a distance of a sensed location along the optical fiber using the monitored time of arrival.

Abstract: An optical fibre designed to simultaneously attenuate the effect of modulation instability and stimulated Raman scattering. A first solution proposes to use non-zero dispersion shifted fibres in the normal dispersion regime to reduce both influences at the same time. A further solution proposes to implement corresponding filter elements in the signal line. A still further solution proposes to additionally provide absorber elements for the Raman wavelengths or to design the core as a leaky one for these wavelengths.

Abstract: A method and apparatus serve to determine spectroscopically a concentration of ethanol in a test sample of an alcoholic aqueous beverage. The determination is based upon providing calibration data which establish a relation between(A) a plurality of transmission values of an electromagnetic radiation in the near infrared region, measured at a unique wavelength at which water is relatively opaque to the radiation while ethanol is relatively transparent thereto, of a plurality of calibration samples of the beverage containing ethanol in differing known concentrations, and(B) the known concentrations of ethanol in the calibration samples. Then, at least one light transmission value of the test sample at the unique wavelength, at which said calibration data were established, is measured. The measured transmission value of the test sample is transformed, by way of the relation established by the calibration data, into an indication of the concentration of ethanol in the test sample.