Abstract: In a method of measuring cumulative polarization mode dispersion (PMD) along the length of a fiber-under-test (FUT), a polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT plural series of light pulses arranged in several groups. Each group comprises at least two series having closely-spaced wavelengths and the same state of polarization (SOP). At least two of such groups are injected and corresponding OTDR traces obtained for each series by averaging the impulse-response signals of the several series in the group. The process is repeated for a number of groups. The PMD is obtained by normalizing the OTDR traces of all of the groups, then computing the difference between each normalized OTDR trace in one group and the corresponding normalized OTDR trace in another group, followed by the mean-square value of the differences. Finally, the PMD is computed as a predetermined function of the mean-square difference.

Abstract: A method and apparatus for measuring at least one polarization-related characteristic of an optical path (FUT) uses an optical source means connected to the FUT at or adjacent a proximal end of the FUT and an analyzing-and-detection unit connected to the FUT at or adjacent its proximal or distal end. The optical source means injects into the FUT at least partially polarized light having a controlled state of polarization (I-SOP). The analyzer-and-detection unit extracts corresponding light from the FUT, analyzes and detects the extracted light corresponding to at least one transmission axis (A-SOP), and processes the corresponding electrical signal to obtain transmitted coherent optical power at each wavelength of light in each of at least two groups of wavelengths, wherein the lowermost (?l) and uppermost (?U) said wavelengths in each said group of wavelengths are closely-spaced.

Abstract: In a method of measuring cumulative polarization mode dispersion (PMD) along the length of a fiber-under-test (FUT), a polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT plural series of light pulses arranged in several groups. Each group comprises at least two series of light pulses having different but closely-spaced wavelengths and the same state of polarization (SOP). At least two, and preferably a large number of such groups, are injected and corresponding OTDR traces obtained for each series of light pulses by averaging the impulse-response signals of the several series of light pulses in the group. The process is repeated for a large number of groups having different wavelengths and/or SOPs. The PMD then is obtained by normalizing the OTDR traces of all of the groups, then computing the difference between each normalized OTDR trace in one group and the corresponding normalized OTDR trace in another group, followed by the mean-square value of the differences.

Abstract: An interferometric optical analyzer apparatus comprises a light source, an interferometer and a detection system for determining the linear response, and subsequently any optical parameter, of one or more optical elements using substantially unpolarized light. In one embodiment, the light source supplies substantially unpolarized coherent light over a predetermined range of optical frequencies. The optical element is coupled in one arm of the interferometer and the other arm of the interferometer is used as a reference. The unpolarized light is first passed through the interferometer then through a three-way polarization splitter unit to split the light into at least three light beams according to preselected polarization axes corresponding to three linearly independent states of polarization. The three light beams are coupled to individual detectors and a controller computes Jones matrix elements from the resulting electrical signals.

Abstract: In a method of measuring cumulative polarization mode dispersion (PMD) along the length of a fiber-under-test (FUT), a polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT plural series of light pulses arranged in several groups. Each group comprises at least two series of light pulses having different but closely-spaced wavelengths and the same state of polarization (SOP). At least two, and preferably a large number of such groups, are injected and corresponding OTDR traces obtained for each series of light pulses by averaging the impulse-response signals of the several series of light pulses in the group. The process is repeated for a large number of groups having different wavelengths and/or SOPs.

Abstract: Portable apparatus for measuring parameters of optical signals propagating concurrently in opposite directions in an optical transmission path between two elements, at least one of the elements being operative to transmit a first optical signal (S1) only if it continues to receive a second optical signal (S2) from the other (10) of said elements, comprises first and second connectors for connecting the apparatus into the optical transmission path in series therewith, and a device connected between the fist and second connectors for propagating at least the second optical signal (S2) towards the one of the elements, and measuring the parameters of the concurrently propagating optical signals (S1, S2). The measurement results may be displayed by a suitable display unit. Where one element transmits signals at two different wavelengths, the apparatus may separate parts of the corresponding optical signal portion according to wavelength and process them separately.

Abstract: Apparatus for measuring polarization mode dispersion (PMD) of a device, e.g. a waveguide, comprises a broadband light source (10,12) for passing polarized broadband light through the device (14), an interferometer (20) for dividing and recombining light that has passed through the device to form interferograms, a polarization separator (30) for receiving the light from the interferometer and separating such received light along first and second orthogonal Feb. 25, 2003 Feb.

Abstract: An interferometric optical analyzer apparatus comprises a light source, an interferometer and a detection system for determining the linear response, and subsequently any optical parameter, of one or more optical elements using substantially unpolarized light. In one embodiment, the light source supplies substantially unpolarized coherent light over a predetermined range of optical frequencies. The optical element is coupled in one arm of the interferometer and the other arm of the interferometer is used as a reference. The unpolarized light is first passed through the interferometer then through a three-way polarization splitter unit to split the light into at least three light beams according to preselected polarization axes corresponding to three linearly independent states of polarization. The three light beams are coupled to individual detectors and a controller computes Jones matrix elements from the resulting electrical signals.

Abstract: A property of a device that is dependent upon both wavelength and state of polarization is measured by; passing through the device an optical signal having its wavelength and SOP varied, the wavelength over a spectral range of the device and the SOP between four Mueller SOPs; measuring the insertion loss of the device for each of the four SOPS and at each wavelength; using the four insertion loss measurements for each of the four different states of polarization for each wavelength to compute the four elements of the first line of the Mueller matrix for each wavelength; and using the Mueller matrix elements, computing insertion loss variations for the device for a multiplicity of input states of polarization in addition to the four states of polarization for which the actual attenuation measurements were made and using the insertion loss variations to compute the polarization and wavelength dependent property.

Abstract: A property of a device that is dependent upon both wavelength and state of polarization is measured by; passing through the device an optical signal having its wavelength and SOP varied, the wavelength over a spectral range of the device and the SOP between four Mueller SOPs; measuring the insertion loss of the device for each of the four SOPS and at each wavelength; using the four insertion loss measurements for each of the four different states of polarization for each wavelength to compute the four elements of the first line of the Mueller matrix for each wavelength; and using the Mueller matrix elements, computing insertion loss variations for the device for a multiplicity of input states of polarization in addition to the four states of polarization for which the actual attenuation measurements were made and using the insertion loss variations to compute the polarization and wavelength dependent property.

Abstract: Apparatus for measuring state of polarization of an input light beam comprises a linear polarizing element (10), e.g. a Glan-Taylor prism, an input fiber and lens (22,24) for directing the input light beam to the linear polarizing element (10), an output stage (26A-26D, 30A-30D, 32A-32D, 34) for receiving the light beam leaving the polarizing element, and at least two waveplates (12A, 12B; 12B, 12C) disposed adjacent each other between the input fiber/lens and the linear polarizing element. Each waveplate has its fast axis oriented at a different predetermined azimuthal angle with respect to the incident light beam. The arrangement is such that first and second portions of the input light beam pass through the linear polarizing element and the two waveplates, respectively, and a third portion of the light beam passes through the linear polarizing element without passing through a waveplate.

Abstract: In order to avoid errors inherent in the measurement of electrical phase differences or pulse arrival time in relative group delay measurements, different optical signals have their intensity modulated at a common high frequency and different permutations are selected. The amplitudes of corresponding electrical signals are detected and phase differences are computed on the basis of trigonometrical relationships. Because the modulation frequency is known, time differences can be deduced. Apparatus for measuring the phase differences conveniently comprises a slotted wheel (26) which passes selected ones or both of the optical signals. One of the optical signals may be split to produce a third signal with a predetermined phase shift, e.g. about 90 degrees at the modulation frequency and the amplitudes of some possible permutations of the three optical signals used to compute the phase difference. The measurements may be used to compute chromatic dispersion, polarization mode dispersion, elongation, and so on.

Abstract: In order to avoid errors inherent in the measurement of electrical phase differences or pulse arrival time in relative group delay measurements, different optical signals have their intensity modulated at a common high frequency and different permutations are selected. The amplitudes of corresponding electrical signals are detected and phase differences are computed on the basis of trigonometrical relationships. Because the modulation frequency is known, time differences can be deduced. Apparatus for measuring the phase differences conveniently comprises a slotted wheel (26) which passes selected ones or both of the optical signals. One of the optical signals may be split to produce a third signal with a predetermined phase shift, e.g. about 90 degrees at the modulation frequency and the amplitudes of some possible permutations of the three optical signals used to compute the phase difference. The measurements may be used to compute chromatic dispersion, polarization mode dispersion, elongation, and so on.

Abstract: Apparatus for measuring very low levels of polarization mode dispersion of optical devices, that is inexpensive, robust and portable, comprises a broadband source and a polarizer for directing substantially completely polarized broadband light into the device under test with the polarization in a plane substantially perpendicular to the propagation direction of the light. Light leaving the device is analyzed spectrally to produce a spectrum of intensity in dependence upon wavelength or frequency of such light for each of at least two mutually orthogonal polarization axes in a plane perpendicular to the propagation axis of the light leaving the device. The spectra are used to compute Stokes parameters s1, s2 and |s3| for each of a plurality of wavelengths within the bandwidth of the broadband light.

Abstract: A method and apparatus for deriving information on a light beam. The light beam is processed by an optical system to produce two quasi-collinear beams propagating in opposite directions, namely pump and probe beams with orthogonal linear polarizations. The beams interact with the medium contained in a cell, which medium is capable to manifest absorption resonance. As a result of the beams interaction with the medium, the intensity of the probe beam transmitted through the medium, considered along a predetermined polarization axis, becomes representative of a particular state of absorption resonance of the medium, which resonance occurs when the frequencies of the pump and probe beams are located within a narrow absorption resonance frequency bandwidth characterizing the medium. The invention finds applications in the laser spectroscopy technology as well as in the construction of frequency stabilized laser sources, optical filters and optical communication systems, among others.