Exfo Electro-optical Engineering, Inc.

Exfo Inc.

Gregory Walter Schinn

Gang He

Hongxin Chen

Daniel Gari&eacute;py

Normand Cyr

Daniel Gariépy

Fran&ccedil;ois Babin

Steeve Potvin

Martin Lamonde

Martin Tremblay

Marc Breton

A polarization-related characteristic of an optical path is determined from a predetermined function of the mean-square of a plurality of differences between polarization-analyzed optical power parameters corresponding to pairs of wavelengths mutually spaced about a midpoint wavelength by a small optical frequency difference. At least some of the said differences correspond to wavelength pairs measured under conditions where at least one of midpoint wavelength, input state of polarization (I-SOP) or analyzed state of polarization (A-SOP) of a pair is different.

Determining a polarization-related characteristic of an optical link

A laser for generating laser light pulses comprises a cavity containing an active optical gain medium () and a spectral filtering device (), a delay device () for delaying light by a predetermined delay time (&#x394;t), means () for extracting a portion of laser light from the cavity, launching said portion into said delay means () and returning the delayed portion to the optical gain medium (), control means () operable to activate the gain medium for a first time period (C) to produce a first laser light pulse (LP) having a duration that is less than the delay time (&#x394;t), and activate the gain medium for a second time period (C) while a said delayed portion of the first light pulse that has been delayed by the delay means (UO) is traversing the gain medium (), thereby to produce a second laser pulse (LP) having a shorter duration and faster risetime than the first laser light pulse (LP), and output means () for outputting the second laser light pulse (LP).

Laser for providing pulsed light and reflectometric apparatus incorporating such a laser

First and second optical fibers are spliced by a mechanical splice-based connecting device having a portion whereby light leaked from the splice can leave the connecting device. A reference power level (P) of light leaked while only the first fiber is inserted into the connecting device, and a measured power level (P) light leaked while both fibers are inserted are measured. Insertion loss of the splice is derived from the measured power level (P), the measured reference power level (P) and a calibration factor (C) previously obtained by using the same or substantially identical measuring apparatus and connecting device to measure a corresponding calibration input power level (P') and calibration reference power level (P&#x2032;) with only the first fiber inserted, and a calibration measured power level (P&#x2032;) and output power level (P&#x2032;) of light coupled into a second fiber after the second fiber has been inserted.

Estimating loss of mechanical splices interconnecting optical fibers, and connector installation tool

A polarization independent optical spectrum analyzer comprises a diffraction grating, input and output slit means and polarization-maintaining multi-pass optics for directing a light beam to and fro across the diffraction grating while maintaining its linear state of polarization. The optical spectrum analyzer further comprises a polarization control unit for decomposing a light beam for analysis into first and second beams having mutually orthogonal states of polarization (SOPs) and then adjusting one or both SOPs so that they are parallel to each other and to one of the dispersion plane of the diffraction grating which is rotated to select different wavelengths of the first and second light beams. The first and second light beams are passed across the diffraction grating repeatedly by multi-pass polarization-maintaining optics and are outputted and detected separately.

Optical spectrum analyzer using a diffraction grating and multi-pass optics

A polarization independent optical spectrum analyzer comprises an inherently polarization sensitive angle-tuned filter element and polarization-maintaining multi-pass optics for directing a light beam to and fro through the tunable filter element while maintaining its linear state of polarization. The optical spectrum analyzer comprises such a tunable optical filter in combination with a polarization control unit for decomposing a light beam for analysis into first and second beams having mutually orthogonal states of polarization (SOPs) and then adjusting one or both SOPs so that they are parallel to each other and to one of the principal axes of the angle-tuned filter which selects different wavelengths of the first and second light beams. The first and second light beams are passed through the filter repeatedly by multi-pass polarization-maintaining optics.

Multi-pass optical spectrum analyzer having a polarization-dependent tunable filter

An optical spectrum analyzer comprises a diffraction grating (DG), a polarization decomposing unit (PDM) for decomposing the input light beam into first and second light beams having mutually-perpendicular linear states of polarization, and two output ports (FP , FP ) each for receiving from the grating, substantially exclusively, a respective one of the polarized light beams (LT, LR) after diffraction by the diffraction grating (DG). Each of the linearly-polarized light beams is directed onto the diffraction grating with its linear state of polarization at any prescribed angle to a corresponding plane of diffraction of the diffraction grating The arrangement is such that the state of polarization of the light beams, at any particular wavelength within an operating band of the analyzer remains substantially unchanged with respect to time, The analyzer also may have a reflector (RAM) for reflecting the light beams leaving the diffraction grating after diffraction a first time so as to return them to the diffraction grating for diffraction a second time.

Optical spectrum analyzer

A photodetector device comprising a photosensitive detector ( ) and one or more interfaces ( ) between dissimilar media is configured so that a light beam (LB) for detection will pass through the interface(s) along a beam axis that is not normal to the interface(s). The deviation (&thgr;) from the normal will be such that polarization dependent transmission introduced at the interface(s) will compensate for inherent polarization dependency of the detector ( ). The deviation may be achieved by inclining the interface(s) relative to a predetermined direction along which the light beam will be incident. Where the photosensitive detector is in a housing ( ) with a window ( ) through which the light beam enters the housing, the housing can be tilted. In such as case, there are three interfaces, one ( ) at the surface of the detector ( ), and one at each surface ( ) of the window ( ). Alternatively, the detector surface and/or the window could be tilted. Where a pigtail fiber ( ) is permanently attached to the photodetector device to input the light beam through an interposed lens ( ), the end of the pigtail fiber may be offset laterally from the lens optical axis (LOA) so that the beam axis deviates from the normal by such an angle that the resulting polarization dependent transmission (PDT) substantially corrects for polarization dependent response (PDR) of the photosensitive detector. An end facet of the pigtail fiber, the lens, and/or the window may be inclined so that they are not perpendicular to the propagation direction of the light beam so as to reduce interference and backreflection effects.

Growing community of inventors

CA

Gregory Walter Schinn