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ABSTRACT: The 2.5-Gb/s coherent 16-quadrature amplitude modulation data is optically transmitted over 75 km and synchronously received by self-homodyning in a real-time in-phase and quadrature receiver, with bit-error ratio below forward-error correction threshold. To this purpose, a phase-noise-tolerant hardware-efficient feedforward carrier recovery was implemented.
IEEE Photonics Technology Letters 01/2011; · 2.19 Impact Factor
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ABSTRACT: In this paper, we review the nondata-aided constant-modulus algorithm (CMA) and a data-aided decision-directed algorithm (DDA) for polarization control and propose different extensions to both algorithms to improve their performance. The first extension to the CMA enables a common carrier recovery (CCR) through differential phase compensation (DPC-CMA). The second extension adapts the CMA for quadrature amplitude modulation signals (CMA-QAM). Both extensions can be combined to form a DPC-CMA for QAM signals (DPC-CMA-QAM). A new, modified DDA (MDDA) considerably increases polarization tracking speeds compared to the original DDA (ODDA). It is also usable for QAM signals. The algorithms are compared in simulations of QPSK and 16-QAM transmission systems. The results show that the DPC extension for the CMA in combination with CCR doubles laser linewidth tolerance and also the CMA-QAM triples polarization control speed compared to the standard CMA for QAM signals. The MDDA is 1.6-4 times faster than the CMA variants and is, at least when QAM signals are transmitted, more hardware-efficient.
IEEE Journal of Selected Topics in Quantum Electronics 11/2010; · 3.78 Impact Factor
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ABSTRACT: Digital signal processing principles for coherent detection of quadrature phase shift keying (QPSK) are presented. Time-critical tasks like phase tracking and data recovery are covered as well as mathematically challenging tasks like polarization control.
OptoeElectronics and Communications Conference (OECC), 2010 15th; 08/2010
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ABSTRACT: We present the recovery of 2.5 Gb/s synchronous 16-point quadrature amplitude modulation data in real-time for an linewidth-times-symbol-duration ratio of 0.00048 after transmission over 1.6 km standard single mode fiber.
OptoeElectronics and Communications Conference (OECC), 2010 15th; 08/2010
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ABSTRACT: In order to build optical transmission systems for 100 Gb/s and above on a single wavelength division multiplexing channel, transition from quadrature phase-shift keying (QPSK) to higher quadrature amplitude modulation (QAM) formats seems to be inevitable. Instead of the usual square constellation QAM, we focus on regular star constellation QAM formats and present a hardware-efficient phase-estimation algorithm that is suitable for all regular star constellations, together with preliminary simulation results.
IEEE Photonics Journal 05/2010; · 2.32 Impact Factor
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ABSTRACT: A multiplier-free phase estimation algorithm based on the barycentre approach for coherent QPSK detection is presented. A selectivity mechanism was developed that significantly improved its performance. In addition to recently published measurement results, theoretical background and new simulation results are presented.
Industrial and Information Systems (ICIIS), 2009 International Conference on; 01/2010
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ABSTRACT: A multiplier-free phase estimation algorithm for coherent QPSK detection is presented. The barycenter approach is modified by a selectivity mechanism that improves performance. In addition to recently published measurement results, theoretical derivations and simulation results are provided.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
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ABSTRACT: The hardware architecture of digital coherent optical receivers supporting >40 Gb/s data rates and general considerations about signal processing algorithms are presented as well as a chipset layout for a 40 Gb/s digital coherent polarization-multiplexed QPSK receiver.
LEOS Annual Meeting Conference Proceedings, 2009. LEOS '09. IEEE; 11/2009
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ABSTRACT: The implementation of algorithms for coherent detection of advanced modulation formats imposes constraints. A hardware-efficient phase estimator is presented, and measurement results with a CMOS receiver chip designed for 40 Gb/s digital coherent polarization-multiplexed QPSK.
Optical Communication, 2009. ECOC '09. 35th European Conference on; 10/2009
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ABSTRACT: We extend a non-data-aided constant modulus algorithm (CMA) by a differential phase compensation (DPC-CMA) and simulate its polarization demultiplexing performance in a digital coherent QPSK receiver against that of the standard CMA.
Summer Topical Meeting, 2009. LEOSST '09. IEEE/LEOS; 08/2009
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ABSTRACT: Fast polarization changes of 40 krad/s and 6-dB polarization-dependent loss (PDL) are tracked in a 2.8-Gb/s real-time coherent quadrature phase-shift keying receiver. The tolerance against fast polarization changes and PDL is measured for different polarization control time constants. The sensitivity penalty of the receiver at a polarization change speed of 40 krad/s is 0.7 dB at bit-error rate (BER) of 1times 10<sup>-3</sup>, with a BER floor of 6.1times10<sup>-7</sup>. With an additional PDL of 6 dB, these figures become 1.7 dB and 9.6 times 10<sup>-6</sup>, respectively.
IEEE Photonics Technology Letters 12/2008; · 2.19 Impact Factor
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ABSTRACT: This letter presents a hardware-efficient frequency estimator and an advanced phase estimation algorithm capable of tracking the phase noise of a 10-GBaud optical quadrature phase-shift-keying transmission system with standard distributed-feedback lasers in the presence of a frequency mismatch up to 1.2 GHz. This algorithm allows us to implement a digital coherent receiver without an analog frequency control circuit.
IEEE Photonics Technology Letters 10/2008; · 2.19 Impact Factor
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ABSTRACT: This paper presents a phase estimation algorithm for a synchronous optical QPSK transmission system. The algorithm has been used in a digital signal processing unit for realtime carrier and data recovery. It has further been combined with polarization multiplex and electronic polarization control.
IEEE/LEOS Summer Topical Meetings, 2008 Digest of the; 08/2008
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ABSTRACT: The tolerance against fast polarization changes and PDL of a digital coherent QPSK receiver is determined in a 2.8 Gb/s realtime polarization-multiplexed transmission experiment. The sensitivity penalty for polarization changes with a speed of 32 krad/s on the Poincare sphere is 0.5 dB.
IEEE/LEOS Summer Topical Meetings, 2008 Digest of the; 08/2008
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ABSTRACT: A digital polarization control system integrated in a 2.8 Gbit/s realtime polarization-multiplexed coherent QPSK system compensates for endless polarization changes having a maximum gradient of 3.5 krad/s (12 krad/s) with 1 dB (3.9 dB) loss in receiver sensitivity.
Optical Fiber communication/National Fiber Optic Engineers Conference, 2008. OFC/NFOEC 2008. Conference on; 03/2008
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ABSTRACT: Coherent optical communication systems promise superior performance, but their realization in real time also poses big technical challenges. After an introduction the potential of coherent optical transmission systems is shown as manifested in offline experiments. Then we present key components that are necessary to realize these systems in real time. We review recent achievements in realtime coherent communication and finally present the results of a realtime QPSK transmission system with a 3x3 coupler in the receiver. The achieved BER at a data rate of 1.4 Gbit/s is well below the FEC threshold.
Optics Express 02/2008; 16(2):866-72. · 3.59 Impact Factor
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T. Pfau,
R. Peveling,
J. Hauden,
N. Grossard,
H. Porte,
Y. Achiam, S. Hoffmann,
S.K. Ibrahim,
O. Adamczyk,
S. Bhandare,
D. Sandel,
M. Porrmann,
R. Noe
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ABSTRACT: This letter presents a coherent digital polarization diversity receiver for real-time polarization-multiplexed synchronous quadrature phase-shift keying transmission with distributed feedback lasers at a data rate of 2.8 Gb/s. The tolerance against fast polarization changes and polarization-dependent loss is evaluated for different filter widths in the carrier recovery circuit. The minimum achieved bit-error rate is 3.4 times 10<sup>-7</sup>.
IEEE Photonics Technology Letters 01/2008; · 2.19 Impact Factor
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T. Pfau,
R. Peveling,
F. Samson,
J. Romoth, S. Hoffmann,
S. Bhandare,
S. Ibrahim,
D. Sandel,
O. Adamczyk,
M. Porrmann,
R. No,
J. Hauden,
N. Grossard,
H. Porte,
D. Schlieder,
A. Koslovsky,
Y. Benarush,
Y. Achiam
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ABSTRACT: This paper presents the implementation of an electronic polarization tracking algorithm which enables real-time polarization-multiplexed synchronous QPSK transmission with DFB lasers. The achieved BER at 2.8 Gbit/s is well below the FEC threshold.
Optical Communication (ECOC), 2007 33rd European Conference and Ehxibition of; 10/2007
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ABSTRACT: This paper focuses on the design of the components required to realize a 10 Gbaud synchronous optical quadrature phase shift keying (QPSK) transmission system. These are a 5 bit 10 Gsamples/s analog-to-digital converter and a digital signal processing unit for carrier and data recovery.
IEEE/LEOS Summer Topical Meetings, 2007 Digest of the; 08/2007
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ABSTRACT: This paper focuses on the recent progress in coherent optical communication using advanced digital signal processing (DSP) technology. In particular the design of DSP components is presented which are required to realize a 10 Gbaud synchronous optical quadrature phase shift keying (QPSK) transmission system. Additionally the measurement results of a preliminary synchronous QPSK transmission setup with distributed feedback (DFB) lasers and real-time digital in-phase and quadrature (I&Q) receiver at a data rate of 1.4 Gbit/s are shown. The minimum bit error ratio (BER) was 1.7ldr10<sup>-5</sup>, lower than ever reported before for a real-time system with DFB lasers.
Microwave Symposium, 2007. IEEE/MTT-S International; 07/2007
