2012 IEEE 3rd International Conference on Photonics, 2012
Abstract We propose and demonstrate a low complexity non decision directed blind carrier recovery... more Abstract We propose and demonstrate a low complexity non decision directed blind carrier recovery algorithm (NDD-CRA) for 16-QAM optical coherent receivers. Through optimization of step size parameter (μ), we obtained similar performance compared to decision-directed phase estimation algorithm, however, our propose scheme has less complexity compared to the decision directed carrier recovery algorithm (DD-CRA) as the proposed scheme does not require any decision feedback module. From simulation, it is observed that the ...
Optical performance monitoring (OPM) is an important issue for proper operation of nextgeneration... more Optical performance monitoring (OPM) is an important issue for proper operation of nextgeneration optical networks. Among various monitored parameters, the optical signal-to-noise ratio (OSNR) and fiber transmission impairments such as chromatic dispersion (CD), polarization mode dispersion (PMD), and polarization dependent loss (PDL) are paid special attention, because they serve information of the channel quality, which helps to manage the network. Several methods have been proposed for monitoring tasks, which are based on pilot tones, RF tones, asynchronous histogram, and fiber nonlinear effects. Most of them need costly devices, tap optical power from the channel, and introduce transmission overhead. On the other hand, in this research, we investigate OPM based on digital coherent receivers, which overcomes such difficulties and ensures cost-efficient, robust and reliable monitoring.
16Th Opto Electronics and Communications Conference, 2011
Abstract We propose and experimentally demonstrate a novel method of monitoring the optical signa... more Abstract We propose and experimentally demonstrate a novel method of monitoring the optical signal-to-noise ratio, which is based on second-and fourth-order statistical moments of the equalized signal from an adaptive filter in coherent optical receivers.
In this paper, we propose a novel hardware-efficient quadrature imbalance compensator circuit for... more In this paper, we propose a novel hardware-efficient quadrature imbalance compensator circuit for coherent optical receivers. Numerical simulations for 16-QAM format show that it can fully compensate the quadrature imbalance over a wide range.
ABSTRACT We propose a novel method of OSNR estimation in Nyquist-WDM transmission systems based o... more ABSTRACT We propose a novel method of OSNR estimation in Nyquist-WDM transmission systems based on the measurement of statistical moments of equalized signals in the digital coherent receiver. Its effectiveness is verified with computer simulations.
Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2011, 2011
We propose a straightforward algorithm to estimate second-order PMD from adaptive FIR-filter tap ... more We propose a straightforward algorithm to estimate second-order PMD from adaptive FIR-filter tap coefficients in a digital coherent optical receiver. The novel algorithm is verified with 100-Gbit/s dual-polarization QPSK experiments.
We propose a novel and unified algorithm that estimates linear impairments in optical transmissio... more We propose a novel and unified algorithm that estimates linear impairments in optical transmission systems from tap coefficients of an adaptive finite-impulse response (FIR) filter in a coherent optical receiver. Measurable impairments include chromatic dispersion (CD), differential group delay (DGD) between two principal states of polarization, second-order polarization-mode dispersion (second-order PMD), and polarization-dependent loss (PDL). We validate our multi-impairment monitoring algorithm by dual-polarization quadrature phase-shift keying (QPSK) transmission experiments.
We propose a novel method of in-band estimation of optical signal-to-noise ratio (OSNR) using a d... more We propose a novel method of in-band estimation of optical signal-to-noise ratio (OSNR) using a digital coherent receiver, where OSNR is determined from second-and fourth-order statistical moments of equalized signals in any modulation format. Our proposed method is especially important in recently-developed Nyquist wavelength-division multiplexed (WDM) systems and/or reconfigurable optical-add/drop-multiplexed (ROADM) networks, because in these systems and networks, we cannot apply the conventional OSNR estimation method based on optical-spectrum measurements of the in-band signal and the out-of-band noise. Effectiveness of the proposed method is validated with computer simulations of Nyquist-WDM systems and ROADM networks using 25-Gbaud quadrature phase-shift keying (QPSK) and 16 quadrature-amplitude modulation (16-QAM) formats.
We propose a novel method of compensation for imbalance between in-phase (I) and quadrature (Q) c... more We propose a novel method of compensation for imbalance between in-phase (I) and quadrature (Q) channels in the front-end circuit of digital coherent optical receivers. Adaptive finite-impulse-response (FIR) filters in the butterfly configuration, which are commonly used for signal equalization and polarization demultiplexing, are modified so as to allow for adjustment of any imbalance between the IQ channels. IQ imbalances under consideration include the gain mismatch, the phase mismatch, and the timing-delay skew. Computer simulations for the dual-polarization quadrature-amplitude-modulation (QAM) format up to an order of 256 show that such IQ imbalances can severely degrade the system performance, especially for higher order QAM; however, using the proposed scheme, we can compensate for them without any significant penalty over a wide range of imbalances.
CLEO:2011 - Laser Applications to Photonic Applications, 2011
Page 1. Frequency-Domain Adaptive Equalization in Digital Coherent Receivers Md. Saifuddin Faruk*... more Page 1. Frequency-Domain Adaptive Equalization in Digital Coherent Receivers Md. Saifuddin Faruk* and Kazuro Kikuchi Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo ...
2012 7th International Conference on Electrical and Computer Engineering, 2012
ABSTRACT Among the wide spectrum of optical performance monitoring (OPM), optical signal-to-noise... more ABSTRACT Among the wide spectrum of optical performance monitoring (OPM), optical signal-to-noise ratio (OSNR) monitoring is very important as it signify a direct measure of signal quality. In this paper, we propose a novel method of OSNR monitoring from the second- and fourth-order statistical moments of equalized signal in 16-QAM coherent optical receivers. The distinct statistical nature of carrier signal and noise enables such estimation. The proposed scheme is verified using computer simulation of 10-Gsymbols/s 16-QAM optical transmission systems. It is found that our scheme can estimate the OSNR with less that 0.5-dB error over a wide monitoring range.
14th International Conference on Computer and Information Technology (ICCIT 2011), 2011
In this paper, the impact of quadrature imbalance (QI) is analyzed for an optical 16-quadrature a... more In this paper, the impact of quadrature imbalance (QI) is analyzed for an optical 16-quadrature amplitude modulation (16-QAM) transmission system that employs digital coherent receivers.
2012 17th Opto-Electronics and Communications Conference, 2012
We propose a novel method of compensation for frontend IQ errors in coherent optical receivers. C... more We propose a novel method of compensation for frontend IQ errors in coherent optical receivers. Computer simulations for the dual-polarization 16-QAM format show that IQ errors can be compensated for over a wide range.
2012 IEEE 3rd International Conference on Photonics, 2012
Abstract We propose and demonstrate a low complexity non decision directed blind carrier recovery... more Abstract We propose and demonstrate a low complexity non decision directed blind carrier recovery algorithm (NDD-CRA) for 16-QAM optical coherent receivers. Through optimization of step size parameter (μ), we obtained similar performance compared to decision-directed phase estimation algorithm, however, our propose scheme has less complexity compared to the decision directed carrier recovery algorithm (DD-CRA) as the proposed scheme does not require any decision feedback module. From simulation, it is observed that the ...
Optical performance monitoring (OPM) is an important issue for proper operation of nextgeneration... more Optical performance monitoring (OPM) is an important issue for proper operation of nextgeneration optical networks. Among various monitored parameters, the optical signal-to-noise ratio (OSNR) and fiber transmission impairments such as chromatic dispersion (CD), polarization mode dispersion (PMD), and polarization dependent loss (PDL) are paid special attention, because they serve information of the channel quality, which helps to manage the network. Several methods have been proposed for monitoring tasks, which are based on pilot tones, RF tones, asynchronous histogram, and fiber nonlinear effects. Most of them need costly devices, tap optical power from the channel, and introduce transmission overhead. On the other hand, in this research, we investigate OPM based on digital coherent receivers, which overcomes such difficulties and ensures cost-efficient, robust and reliable monitoring.
16Th Opto Electronics and Communications Conference, 2011
Abstract We propose and experimentally demonstrate a novel method of monitoring the optical signa... more Abstract We propose and experimentally demonstrate a novel method of monitoring the optical signal-to-noise ratio, which is based on second-and fourth-order statistical moments of the equalized signal from an adaptive filter in coherent optical receivers.
In this paper, we propose a novel hardware-efficient quadrature imbalance compensator circuit for... more In this paper, we propose a novel hardware-efficient quadrature imbalance compensator circuit for coherent optical receivers. Numerical simulations for 16-QAM format show that it can fully compensate the quadrature imbalance over a wide range.
ABSTRACT We propose a novel method of OSNR estimation in Nyquist-WDM transmission systems based o... more ABSTRACT We propose a novel method of OSNR estimation in Nyquist-WDM transmission systems based on the measurement of statistical moments of equalized signals in the digital coherent receiver. Its effectiveness is verified with computer simulations.
Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2011, 2011
We propose a straightforward algorithm to estimate second-order PMD from adaptive FIR-filter tap ... more We propose a straightforward algorithm to estimate second-order PMD from adaptive FIR-filter tap coefficients in a digital coherent optical receiver. The novel algorithm is verified with 100-Gbit/s dual-polarization QPSK experiments.
We propose a novel and unified algorithm that estimates linear impairments in optical transmissio... more We propose a novel and unified algorithm that estimates linear impairments in optical transmission systems from tap coefficients of an adaptive finite-impulse response (FIR) filter in a coherent optical receiver. Measurable impairments include chromatic dispersion (CD), differential group delay (DGD) between two principal states of polarization, second-order polarization-mode dispersion (second-order PMD), and polarization-dependent loss (PDL). We validate our multi-impairment monitoring algorithm by dual-polarization quadrature phase-shift keying (QPSK) transmission experiments.
We propose a novel method of in-band estimation of optical signal-to-noise ratio (OSNR) using a d... more We propose a novel method of in-band estimation of optical signal-to-noise ratio (OSNR) using a digital coherent receiver, where OSNR is determined from second-and fourth-order statistical moments of equalized signals in any modulation format. Our proposed method is especially important in recently-developed Nyquist wavelength-division multiplexed (WDM) systems and/or reconfigurable optical-add/drop-multiplexed (ROADM) networks, because in these systems and networks, we cannot apply the conventional OSNR estimation method based on optical-spectrum measurements of the in-band signal and the out-of-band noise. Effectiveness of the proposed method is validated with computer simulations of Nyquist-WDM systems and ROADM networks using 25-Gbaud quadrature phase-shift keying (QPSK) and 16 quadrature-amplitude modulation (16-QAM) formats.
We propose a novel method of compensation for imbalance between in-phase (I) and quadrature (Q) c... more We propose a novel method of compensation for imbalance between in-phase (I) and quadrature (Q) channels in the front-end circuit of digital coherent optical receivers. Adaptive finite-impulse-response (FIR) filters in the butterfly configuration, which are commonly used for signal equalization and polarization demultiplexing, are modified so as to allow for adjustment of any imbalance between the IQ channels. IQ imbalances under consideration include the gain mismatch, the phase mismatch, and the timing-delay skew. Computer simulations for the dual-polarization quadrature-amplitude-modulation (QAM) format up to an order of 256 show that such IQ imbalances can severely degrade the system performance, especially for higher order QAM; however, using the proposed scheme, we can compensate for them without any significant penalty over a wide range of imbalances.
CLEO:2011 - Laser Applications to Photonic Applications, 2011
Page 1. Frequency-Domain Adaptive Equalization in Digital Coherent Receivers Md. Saifuddin Faruk*... more Page 1. Frequency-Domain Adaptive Equalization in Digital Coherent Receivers Md. Saifuddin Faruk* and Kazuro Kikuchi Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo ...
2012 7th International Conference on Electrical and Computer Engineering, 2012
ABSTRACT Among the wide spectrum of optical performance monitoring (OPM), optical signal-to-noise... more ABSTRACT Among the wide spectrum of optical performance monitoring (OPM), optical signal-to-noise ratio (OSNR) monitoring is very important as it signify a direct measure of signal quality. In this paper, we propose a novel method of OSNR monitoring from the second- and fourth-order statistical moments of equalized signal in 16-QAM coherent optical receivers. The distinct statistical nature of carrier signal and noise enables such estimation. The proposed scheme is verified using computer simulation of 10-Gsymbols/s 16-QAM optical transmission systems. It is found that our scheme can estimate the OSNR with less that 0.5-dB error over a wide monitoring range.
14th International Conference on Computer and Information Technology (ICCIT 2011), 2011
In this paper, the impact of quadrature imbalance (QI) is analyzed for an optical 16-quadrature a... more In this paper, the impact of quadrature imbalance (QI) is analyzed for an optical 16-quadrature amplitude modulation (16-QAM) transmission system that employs digital coherent receivers.
2012 17th Opto-Electronics and Communications Conference, 2012
We propose a novel method of compensation for frontend IQ errors in coherent optical receivers. C... more We propose a novel method of compensation for frontend IQ errors in coherent optical receivers. Computer simulations for the dual-polarization 16-QAM format show that IQ errors can be compensated for over a wide range.
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