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Author

C. Schulien

Bio: C. Schulien is an academic researcher. The author has contributed to research in topics: Polarization mode dispersion & Digital signal processing. The author has an hindex of 11, co-authored 22 publications receiving 842 citations.

Papers
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Journal ArticleDOI
01 Jan 2008
TL;DR: In this paper, the use of a coherent digital receiver for compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard is discussed.
Abstract: We discuss the use of a coherent digital receiver for the compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard. We present experimental results on the transmission performance of 111 Gbit/s POLMUX-RZ-DQPSK. For a dense WDM setup with channels carrying 111 Gbit/s with a 50 GHz channel spacing (2.0 bits/s/Hz), we show the feasibility of 2375 km transmission. This is enabled through coherent detection which results in excellent noise performance, and subsequent electronic equalization which provides the high tolerance to polarization mode dispersion and chromatic dispersion (CD). Furthermore, we discuss the impact of sampling and digital signal processing with either 1 or 2 samples/bit. We show that when combined with low-pass electrical filtering, 1 sample/bit signal processing is sufficient to obtain a large tolerance towards CD. The proposed modulation and detection techniques enable 111 Gbit/s transmission that is directly compatible with the existing 10 Gbit/s infrastructure.

405 citations

Proceedings Article
25 Mar 2007
TL;DR: In this paper, the authors demonstrate spectrally efficient (2.0 b/s/Hz) transmission of 10 x 111 Gbit/s polarisation multiplexed 27.75 Gbaud RZ-DQPSK over 2375km of SSMF and 5 add-drop nodes.
Abstract: We demonstrate spectrally efficient (2.0 b/s/Hz) transmission of 10 x 111 Gbit/s polarisation multiplexed 27.75 Gbaud RZ-DQPSK over 2375km of SSMF and 5 add-drop nodes. Coherent equalisation enables polarisation recovery and high chromatic dispersion tolerance.

117 citations

Proceedings ArticleDOI
23 May 2008
TL;DR: In this article, the effect of PDL on the performance of a DQPSK signal was investigated and it was shown that the orientation of the PDL element has a major impact on the OSNR performance.
Abstract: We present simulations and measurements on the effect of PDL on a POLMUX-NRZ- DQPSK signal. We show that the orientation between the POLMUX signal and PDL element has a major impact on the OSNR performance.

50 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a novel approach to measure the Lorentzian linewidth of a laser source based on a heterodyne detection scheme, such as may be implemented in a coherent optical receiver for data communications, using both in-phase and quadrature information of the optical field.
Abstract: In this letter, we present a novel approach to measure the Lorentzian linewidth of a laser source. The approach is based on a heterodyne detection scheme, such as may be implemented in a coherent optical receiver for data communications, using both in-phase and quadrature information of the optical field. In contrast to previously published works, this approach does not suffer from modulation effects on the laser output.

38 citations

Proceedings ArticleDOI
23 Jul 2007
TL;DR: For 111-Gb/s POLMUX-RZ-DQPSK, the advantage of coherent equalization over direction detection for compensation of both chromatic dispersion and differential group delay is experimentally shown.
Abstract: We discuss coherent equalization to realize robust 111-Gb/s transmission. For 111-Gb/s POLMUX-RZ-DQPSK we experimentally show the advantage of coherent equalization over direction detection for compensation of both chromatic dispersion and differential group delay.

36 citations


Cited by
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Journal ArticleDOI
TL;DR: Using the analytical solution an upper bound on the number of taps required to compensate chromatic dispersion is obtained, with simulation revealing an improved bound of 2.2 taps per 1000ps/nm for 10.7GBaud data.
Abstract: Digital filters underpin the performance of coherent optical receivers which exploit digital signal processing (DSP) to mitigate transmission impairments. We outline the principles of such receivers and review our experimental investigations into compensation of polarization mode dispersion. We then consider the details of the digital filtering employed and present an analytical solution to the design of a chromatic dispersion compensating filter. Using the analytical solution an upper bound on the number of taps required to compensate chromatic dispersion is obtained, with simulation revealing an improved bound of 2.2 taps per 1000ps/nm for 10.7GBaud data. Finally the principles of digital polarization tracking are outlined and through simulation, it is demonstrated that 100krad/s polarization rotations could be tracked using DSP with a clock frequency of less than 500MHz.

1,201 citations

Journal ArticleDOI
05 Jun 2006
TL;DR: This paper discusses the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlights their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion.
Abstract: Fiber-optic communication systems form the high-capacity transport infrastructure that enables global broadband data services and advanced Internet applications. The desire for higher per-fiber transport capacities and, at the same time, the drive for lower costs per end-to-end transmitted information bit has led to optically routed networks with high spectral efficiencies. Among other enabling technologies, advanced optical modulation formats have become key to the design of modern wavelength division multiplexed (WDM) fiber systems. In this paper, we review optical modulation formats in the broader context of optically routed WDM networks. We discuss the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity

772 citations

Journal ArticleDOI
TL;DR: In this article, a theoretical analysis of the dual-polarization constant modulus algorithm is presented, where the control surfaces several different equalizer algorithms are derived, including the decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDm-16-QAM).
Abstract: Digital coherent receivers have caused a revolution in the design of optical transmission systems, due to the subsystems and algorithms embedded within such a receiver. After giving a high-level overview of the subsystems, the optical front end, the analog-to-digital converter (ADC) and the digital signal processing (DSP) algorithms, which relax the tolerances on these subsystems are discussed. Attention is then turned to the compensation of transmission impairments, both static and dynamic. The discussion of dynamic-channel equalization, which forms a significant part of the paper, includes a theoretical analysis of the dual-polarization constant modulus algorithm, where the control surfaces several different equalizer algorithms are derived, including the constant modulus, decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDM-16-QAM). Synchronization algorithms employed to recover the timing and carrier phase information are then examined, after which the data may be recovered. The paper concludes with a discussion of the challenges for future coherent optical transmission systems.

772 citations

Journal ArticleDOI
Han Sun1, Kuang-Tsan Wu1, Kim B. Roberts1
TL;DR: Continuous real-time measurements are shown from a coherent 40 Gb/s transmission system that uses Dual-Polarization Quadrature Phase Shift Keying (DP-QPSK) modulation, using digital compensation for dispersion and polarization effects.
Abstract: Continuous real-time measurements are shown from a coherent 40 Gb/s transmission system that uses Dual-Polarization Quadrature Phase Shift Keying (DP-QPSK) modulation. Digital compensation is used for dispersion and polarization effects, with little performance degradation created by 150 ps of rapidly varying 1st-order PMD.

474 citations

Journal ArticleDOI
01 Jan 2008
TL;DR: In this paper, the use of a coherent digital receiver for compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard is discussed.
Abstract: We discuss the use of a coherent digital receiver for the compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard. We present experimental results on the transmission performance of 111 Gbit/s POLMUX-RZ-DQPSK. For a dense WDM setup with channels carrying 111 Gbit/s with a 50 GHz channel spacing (2.0 bits/s/Hz), we show the feasibility of 2375 km transmission. This is enabled through coherent detection which results in excellent noise performance, and subsequent electronic equalization which provides the high tolerance to polarization mode dispersion and chromatic dispersion (CD). Furthermore, we discuss the impact of sampling and digital signal processing with either 1 or 2 samples/bit. We show that when combined with low-pass electrical filtering, 1 sample/bit signal processing is sufficient to obtain a large tolerance towards CD. The proposed modulation and detection techniques enable 111 Gbit/s transmission that is directly compatible with the existing 10 Gbit/s infrastructure.

405 citations