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Stuttgart, Germany

Koch B.,University of Paderborn | Koch B.,Novoptel GmbH | Noe R.,University of Paderborn | Noe R.,Novoptel GmbH | And 2 more authors.
Electronics Letters | Year: 2011

For the first time, an endless optical polarisation tracking speed of 100krad/s is demonstrated. During a 64-hour measurement, a polarisation trajectory of 18 gigaradian length was tracked with mean and maximum polarisation errors of 0.096 and 0.220 rad, respectively. © 2011 The Institution of Engineering and Technology.


Koch B.,University of Paderborn | Koch B.,Novoptel GmbH | Noe R.,University of Paderborn | Noe R.,Novoptel GmbH | And 2 more authors.
Conference on Optical Fiber Communication, Technical Digest Series | Year: 2014

We present the first endless polarization controller with a THz optical bandwidth, much wider than that of electronic polarization controllers. It is suitable for demultiplexing polarization-multiplexed signals at tracking speeds up to 70 krad/s. © 2014 OSA.


Koch B.,University of Paderborn | Koch B.,Novoptel GmbH | Noe R.,University of Paderborn | Noe R.,Novoptel GmbH | And 2 more authors.
Optics Express | Year: 2014

Following an initial discussion of control error signal generation, we present new developments and applications of automatic endless optical polarization control based on a commercial electrooptic LiNbO3 polarization transformer: (i) Fast tracking and subsequent demultiplexing of DPSK/DQPSK/QAM polarization channels was hitherto limited to a fairly fixed optical input power. With APD photoreceivers used for residual interference detection, we demonstrate here an optical level tolerance of at least 7 dB, compared to only 3 dB for PIN photoreceivers. DPSK channel polarizations are tracked at up to 40 krad/s and higher speed on the Poincaré sphere. (ii) High-order optical modulation schemes require increased accuracy of the polarization controller in the demultiplexer. This is possible at the expense of a reduced tracking speed. We achieve a mean polarization extinction ratio of >40 dB or <0.02 rad error while tracking arbitrary endless polarization changes of up to 1000 rad/s. (iii) While electronic polarization tracking in coherent receivers is currently limited to a symbol rate of about 28 GBaud we show optical polarization tracking of a signal with 1 THz bandwidth. © 2014 Optical Society of America.


Noe R.,University of Paderborn | Noe R.,Novoptel GmbH | Koch B.,University of Paderborn | Koch B.,Novoptel GmbH | And 2 more authors.
Journal of Lightwave Technology | Year: 2015

We formulate the concatenation properties of polarization-dependent loss (PDL) based on extinction rather than linear units. The advantage of this is that corresponding PDL vectors, defined with length proportional to extinction, can be added with much better accuracy than the traditional linear ones, in particular when PDL is of nonnegligible quantity. We also describe either two concatenated PDL elements or a general constant optical element as a combined PDL element and a retarder, thereby obtaining not only input-but also output-referred PDL vectors. We then propose to model a general optical transmission medium by the concatenation of many differential group delay (DGD) and PDL sections and retarders. An inverse scattering algorithm is provided which allows this physical structure to be obtained from the Jones matrix impulse response. Experimentally, we obtain the latter from the Mueller matrices measured in the optical frequency domain. The finally resulting distributed device structure is displayed in DGD and PDL profiles. The covariance matrix of the normalized Stokes vectors of scrambled polarizations equals 1/3 times the identity matrix. Based on this, we present yet another PDL measurement technique, the sqrt(3) scrambling method. It needs no polarimeter and determines low PDL values with better accuracy than the gradient search-based extinction method. © 2014 IEEE.


Koch B.,University of Paderborn | Koch B.,Novoptel GmbH | Noe R.,University of Paderborn | Noe R.,Novoptel GmbH | And 2 more authors.
Electronics Letters | Year: 2013

Presented is endless optical control not only of the state-of-polarisation of an analysed signal and its orthogonal, but also of the phase difference between the two. The normalised Stokes vector space is thereby stabilised, at the polarisation scrambling speeds of up to 20 krad/s. © The Institution of Engineering and Technology 2013.

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