Exfo Inc.

Exfo Electro-optical Engineering, Inc.

Hongxin Chen

Gang He

Normand Cyr

Gregory Walter Schinn

Bernard Ruchet

Daniel Gariepy

François Babin

Daniel Gariépy

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

There is provided a method for determining a noise parameter characterizing an optical Signal-Under-Test (SUT) having a signal contribution, an Amplified Spontaneous Emission (ASE) noise contribution and a non-ASE optical noise contribution, such as a carrier-leakage contribution or a depolarized-signal contribution, within an optical-signal bandwidth. The method comprises acquiring optical spectrum trace(s) of the SUT, discriminating at least the non-ASE optical noise contribution from the ASE-noise contribution using the optical spectrum trace(s) and/or a trace obtained from the optical spectrum trace(s); and determining the noise parameter using discriminated non-ASE optical noise contribution and/or the discriminated ASE-noise contribution.

Characterization of non-ASE noise on optical signals

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

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.

Polarization optical time domain reflectometer and method of determining PMD

A widely-tunable laser apparatus comprises a plurality of tunable lasers having different ranges that overlap to encompass a desired operating range of wavelengths (for example from 1250 nm to 1650 nm) of the widely-tunable laser apparatus. The tunable lasers are tunable synchronously and selectively with their respective outputs connected in common to sweep the output of the widely-tunable laser apparatus substantially continuously over said operating range. The tunable lasers share the same tuning means which has a plurality of independent channels, each for light from a respective one of the tunable lasers.

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Hongxin Chen