Joint blind equalization of CD and RSOP using a time-frequency domain Kalman filter structure in Stokes vector direct detection system

Cui, Nan; Zheng, Zibo; Zhang, Xiaoguang; Wei, Yi; Guo, Ruipu; Zhang, Wenbo; Tang, Xianfeng; Xu, Hengying; Xi, Lixia

doi:10.1364/oe.27.011557

Cited by 17 publications

(8 citation statements)

References 23 publications

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“…3, components of Stokes vectors are not linear items. For this reason, a linear equalizer such as fiber CD compensator cannot be applied directly when S r = S t , otherwise nonlinear terms would be induced, resulting in performance degradation [13]. Consequently, correct RSOP equalization is a significant prerequisite for SV-DD systems, and it is highly desired to cope with RSOP when CD is introduced.…”

Section: Principlementioning

confidence: 99%

“…Therefore, its computation complexity should be divided by the length of a frame, and this value is 320 in our simulations. The computational complexities of these three schemes for every recovered symbol [13] are listed in Table 3. Compared to Ori, the proposed Imp needs more multiplication operations but fewer addition operations, contributing to nearly no increase in total complexity.…”

Section: Computation Complexitymentioning

confidence: 99%

“…That means conventional digital signal processing (DSP) cannot be done until the optical field signal is recovered by proper rotation state of polarization (RSOP) equalization. As mentioned in [13], RSOP should be equalized before the fiber chromatic dispersion (CD) compensation, otherwise, the induced nonlinear terms will seriously degrade the transmission performance. Therefore, correct polarization de-multiplexing is a significant prerequisite for SV-DD, and it is highly desired to cope with the interplay between RSOP and CD.…”

Section: Introductionmentioning

confidence: 99%

“…A real-value equalizer with 3 inputs and 2 outputs has been proposed in [14] for polarization de-multiplexing, and its weights are updated through decision feedback least mean square (LMS) or recursive least square (RLS) algorithms. Besides, the Kalman filter is introduced to achieve faster convergence speed and stronger capability for RSOP tracking [13], [15], [16]. However, conventional adaptive equalizers and Kalman filters all need certain decision feedback structures to update their coefficients.…”

Section: Introductionmentioning

confidence: 99%

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Adaptive Blind Stokes-Space Based Equalizer for RSOP in SV-DD Systems With High Chromatic Dispersion Tolerance

Jin

et al. 2020

IEEE Photonics J.

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Polarization de-multiplexing becomes challenging in Stokes vector-direct detection (SV-DD) systems, especially when the rotation of state of polarization (RSOP) and fiber chromatic dispersion (CD) are induced. To address this issue, an adaptive blind RSOP equalizer based on Stokes space is proposed. After theoretical analysis, it is found that the distribution of transmitted signals in Stokes space keeps a paraboloid. Based on this analysis, an adaptive scheme is proposed to track the symmetry axis of paraboloid for the first time. It is worth noticing that not only CD but also high-order modulation formats could not change the paraboloid distribution. Therefore, our algorithm has strong robustness to CD and good suitability for SV-DD systems with different modulation formats. In our simulation, the conventional Stokes space-based method and the training sequences (TS) method are both evaluated for comparison. The results show that our scheme can track RSOP of 20 Mrad/s and 8 Mrad/s at hard-decision forward error correction threshold in 28 Gbaud 4-level quadrature amplitude modulation (4-QAM) and 16-QAM SV-DD systems after 100 km fiber transmission, respectively. No additional computational complexity is required compared to the conventional Stokes space-based method. Moreover, compared to the TS-based method, there is no need to know the actual channel information, contributing to good flexibility.

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Section: Principlementioning

confidence: 99%

Section: Computation Complexitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Adaptive Blind Stokes-Space Based Equalizer for RSOP in SV-DD Systems With High Chromatic Dispersion Tolerance

Jin

et al. 2020

IEEE Photonics J.

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“…However, PolSK have critical drawbacks such that it is vulnerable to SOP change, especially rotation of SOP (RSOP). When transmitting an optical signal, the polarization changes according to the characteristics of the optical fiber and optical active devices; specifically, external environmental factors can cause SOP changes from a few kilorads per second to a few megarads per second [10][11][12][13]. Thus, when the signal is modulated and transmitted through optical fiber, it is received in a different polarization state.…”

Section: Introductionmentioning

confidence: 99%

SOP Change Robust Optical Modulation Based on Dual Polarization Modulation for Multi-Dimensional Optical Transmission

Lee

Han

2021

IEEE Access

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In optical transmission technique using optical polarization, the change of state of polarization (SOP) and the rotation of SOP (RSOP) during optical transmission has a significant impact o the transmission performance. We propose polarized intensity rotational frequency shift keying (PIR-FSK) as a novel modulation technique in change of SOP and RSOP-tolerant optical transmissions. The proposed PIR-FSK signal does not affect the entire intensity of the optical carrier by modulating the sinusoidal signals on each X and Y-polarized optical carrier. Therefore, the proposed PIR-FSK modulation and optical carrier intensity modulation can operate at the same time. Moreover, since the proposed technique does not modulate the signal using the SOP unlike the PolSK, PIR-FSK is not affected by SOP changes that occur during transmission, and the signal does not be degraded even with RSOP. We demonstrated that the signals modulated using the proposed PIR-FSK modulation have higher signal capacity and efficiency compared to the signal modulated using PolSK modulation. INDEX TERMSFrequency shift keying, Multi-dimensional optical transmission,Polarization shift keying, Rotation of State of Polarization(RSOP).

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Polarization demultiplexing scheme for probabilistic shaping Stokes vector direct detection system using extended Kalman filter

Zhang

Zheng

et al. 2020

Optics Communications

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Joint blind equalization of CD and RSOP using a time-frequency domain Kalman filter structure in Stokes vector direct detection system

Cited by 17 publications

References 23 publications

Adaptive Blind Stokes-Space Based Equalizer for RSOP in SV-DD Systems With High Chromatic Dispersion Tolerance

Adaptive Blind Stokes-Space Based Equalizer for RSOP in SV-DD Systems With High Chromatic Dispersion Tolerance

SOP Change Robust Optical Modulation Based on Dual Polarization Modulation for Multi-Dimensional Optical Transmission

Polarization demultiplexing scheme for probabilistic shaping Stokes vector direct detection system using extended Kalman filter

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