QPSK Training Sequence-Based Both OSNR and Chromatic Dispersion Monitoring in DWDM Systems

We design a quadrature phase-shift keying training sequence (QPSK-TS) for monitoring both optical signal-to-noise ratio (OSNR) and chromatic dispersion (CD) in a dense wavelength division multiplexing (DWDM) system. By applying fast Fourier transform on the QPSK-TS, a comb-like spectrum with discrete peaks can be obtained. OSNR can be calculated by measuring the power of the amplified spontaneous emission (ASE) noise in the gaps between these peaks. Moreover, we search the optimal order in the fractional domain to calculate the CD after applying fractional Fourier transform on the QPSK-TS signal. The proposed method shows large ASE noise and optical nonlinearity tolerance in simulation results (<inline-formula><tex-math notation="LaTeX">$<$</tex-math></inline-formula>1.0 dB error within 24 dB after transmission over 1000 km with 3 dBm per channel launch power, and <inline-formula><tex-math notation="LaTeX">$<$ </tex-math></inline-formula>90 ps/nm error within 33400 ps/nm). Furthermore, the experimental results demonstrate high accuracy of the proposed method (<inline-formula><tex-math notation="LaTeX">$\leq$</tex-math></inline-formula>1.0 dB error within 28 dB and <inline-formula><tex-math notation="LaTeX">$<$</tex-math></inline-formula>40 ps/nm error within 1670 ps/nm after 100 km single channel transmission).

[1]  Fabio Pittala,et al.  Fast and robust CD and DGD estimation based on data-aided channel estimation , 2011, 2011 13th International Conference on Transparent Optical Networks.

[2]  Koichi Ishihara,et al.  Fast chromatic dispersion estimation for coherent optical transmission systems , 2012 .

[3]  Yueming Lu,et al.  A novel method for chromatic dispersion estimation with lower computation complexity in fractional domain , 2018, International Conference on Optical Instruments and Technology.

[4]  K. M. M. Prabhu,et al.  The fractional Fourier transform: theory, implementation and error analysis , 2003, Microprocess. Microsystems.

[5]  Idelfonso Tafur Monroy,et al.  Combined CD and DGD Monitoring Based on Data-Aided Channel Estimation , 2011 .

[6]  Deming Liu,et al.  Fractional Fourier Transformation-Based Blind Chromatic Dispersion Estimation for Coherent Optical Communications , 2016, Journal of Lightwave Technology.

[7]  Takeshi Hoshida,et al.  Differential pilots aided in-band OSNR monitor with large nonlinear tolerance , 2015, 2015 Optical Fiber Communications Conference and Exhibition (OFC).

[8]  A. Tran,et al.  Chromatic dispersion estimation in 40 Gb/s coherent polarization-multiplexed single carrier system using complementary Golay sequences , 2012, OFC/NFOEC.

[9]  Huibin Zhou,et al.  A fast and robust blind chromatic dispersion estimation based on fractional fourier transformation , 2015, 2015 European Conference on Optical Communication (ECOC).

[10]  Takeshi Hoshida,et al.  An accurate nonlinear noise insensitive OSNR monitor , 2016, 2016 Optical Fiber Communications Conference and Exhibition (OFC).

[11]  Yaojun Qiao,et al.  Joint OSNR and Interchannel Nonlinearity Estimation Method Based on Fractional Fourier Transform , 2017, Journal of Lightwave Technology.

[12]  Olcay Akay,et al.  Fractional convolution and correlation via operator methods and an application to detection of linear FM signals , 2001, IEEE Trans. Signal Process..

[13]  Md. Saifuddin Faruk.  Optical Performance Monitoring in Digital Coherent Receivers , 2011 .

[14]  Yoshiaki Kisaka,et al.  Field trial of distance-adaptive optical transmission with digital in-band OSNR estimation. , 2016, Optics express.

[15]  Yaojun Qiao,et al.  A Novel Noise-Insensitive Chromatic Dispersion Estimation Method Based on Fractional Fourier Transform of LFM Signals , 2017, IEEE Photonics Journal.

[16]  J.H. Lee,et al.  A Review of the Polarization-Nulling Technique for Monitoring Optical-Signal-to-Noise Ratio in Dynamic WDM Networks , 2006, Journal of Lightwave Technology.