Thorlabs Gmbh

Tektronix Munich

Adalbert Bandemer

Egbert Krause

Jens Peupelmann

Dieter Palme

Walter Nowak

Michael Sauer

Ingolf Baumann

Johann Meissner

A fiber polarimeter has one or more oblique fiber Bragg gratings disposed one behind the other in a fiber. The fiber Bragg gratings couple out portions of a light wave input to the fiber depending on its polarization. For more than one fiber Bragg grating a wave plate is disposed in the fiber between consecutive fiber Bragg gratings. The portions of the light wave from the fiber Bragg grating(s) are detected to produce measurement data that is used to calculate four Stokes parameters for determining polarization, degree of polarization and/or power of the light wave.

Fiber polarimeter, the use thereof, as well as polarimetric method

A system and method for monitoring all the characteristic parameters of a DWDM communication system is implemented with two variants. Firstly, this is achieved by means of a specific grating spectrometer displaying a high resolution and a high-speed sampling of the measured values, and secondly by the application of an opto-electronic cross correlator as a purely electronic solution. The grating spectrometer is expediently a particular system in a mixed array according to Ebert and Fastie, wherein the light to be measured passes four times through the grating in a specific manner. The opto-electronic cross correlator can mix the working light with a reference light tunable in terms of its frequency to form an electrical low-frequency signal that is analyzed in a high-impedance operation.

System and method for monitoring the performance of dense wavelength division multiplexing optical communications systems

The invention describes a transmission component for producing chromatic dispersion which can be predetermined, having

Fiber transmission element for generating a chromatic dispersion

A PMD emulation, measurement and compensation device is based upon an emulation device having a piece of fiber having a fixed differential group delay (DGD) and another short piece of fiber (or double refracting crystal) having a variable differential group delay (T-DGD). The two pieces of fiber are coupled with a non-zero torsional angle between their respective double refractive axes, preferably 45&#xb0;. A fiber squeezer/stretcher is used to provide the variable DGD for the short piece of fiber. Various serial couplings of DGD and T-DGD fiber may be added to provide greater control and accuracy, with the torsional angles preferably alternating. Such an emulation device may be incorporated into a measurement device to measure the PMD-related distortion of an optical signal. Further the measurement device may be used in a PMD compensator where an emulation device in series with the optical signal path is controlled until the measured PMD in the PMD-related distorted optical signal is minimized.

PMD emulation, measurement and compensation device

Highly accurate calibration of a polarimeter of the type having at least four detectors involves using four known states of polarisation of an input light signal (calibration polarisations) and at least one further state of polarisation. All input states of polarisation to the polarimeter have unity normalised power of the light signal and unity degree of polarisation. A Stokes matrix for the four calibration polarisations is generated with at least one variable correction parameter, and a correction matrix is determined from the Stokes matrix and a corresponding detector current matrix measured by the polarimeter. An optimisation criterion that is a function of the degrees of polarisation for the states of polarisation as measured by the polarimeter is generated. The correction parameter is varied iteratively to minimise the optimisation criterion so that the polarimeter is calibrated to produce unity power and degree of polarisation for any input state of polarisation.

Highly accurate calibration of polarimeters

A system for producing a presettable polarization mode dispersion includes an initial polarization splitter/combiner element, which divides the incoming signal into two signals in vertical polarization alignment to one another, a delaying unit, which is installed in one of the signal paths of the two split signals, and a second polarization splitter/combiner element, which reunites the two separated signals. The invention is distinguished in that, for the production of a second-order polarization mode dispersion, an element is provided which twists the polarization main axles ahead of and behind the element toward one another by an appropriate angle, and that the light signal emitted from this element is fed into a device, which likewise consists of a polarization splitter/combiner element, a delaying path, and an additional polarization splitter/combiner element for bringing the two signal paths back together.

Polarization mode dispersion emulator

The invention relates to a device for detecting the PMD of optoelectronic transmission lines. The inventive device is characterized in that it comprises a narrow-band, tunable laser, whose illumination is superimposed with the illumination of the transmission line to be analyzed and an optoelectronic heterodyne receiver which receives the superimposed signal.

Device for detecting the PMD of optoelectronic transmission lines

An arrangement and method for producing a predeterminable polarization mode dispersion by means of double refracting elements provides for the production of a second-order polarization mode dispersion. An element is envisaged which twists the polarization principal axes by an appropriate angle at the output of an arrangement for producing first-order PMD, and the light signal exiting this element is fed into an arrangement which is also an arrangement for producing first-order PMD to produce an output signal having both first- and second-order PMD.

Arrangement and method for producing a predeterminable polarization mode dispersion

The invention describes a system to compensate distortions caused by polarization modulation dispersion (PMD) in optical transmission systems and particularly transmission fibers, with a measuring device for distortions caused by PMD, an emulation unit for adjustable PMD values, a polarization transformation element, which adjusts the polarization of the signals coming from a transmission system to the PMD emulation unit, an analyzer and control unit, connected to the output signal of the measuring device, which unit controls the emulation unit and the polarization adjuster element. The invention is distinguished in that the emulation unit has a PMD emulator, which emulates PMD of second or higher order and matches PMD of a real transmission fiber as exactly as possible, and that the one or more PMD emulators compensate one or more transmission channels, and/or that the measuring device optically detects the PMD directly or by way of the detection of polarization conditions.

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Herrsching, Germany

Adalbert Bandemer