Meng Yan

Adaptive blind equalization for coherent optical BPSK system

The widely used CMA equalization fails in coherent optical BPSK systems. A novel adaptive blind equalization method is proposed and experimentally verified in terms of frequency offset, laser linewidth, CD/PMD and polarization scrambling tolerance.

Superimposition and detection of frequency modulated tone for light path tracing employing digital signal processing and optical filter

We propose a novel method for light path tracing and demonstrate it in 112Gb/s DP-16QAM transmission. The S/N of the detected label exceeds 24dB after 20span transmission. No crosstalk was observed in neighboring DWDM channels.

Inter-Carrier Interference Suppression in No-Guard-Interval Orthogonal Frequency-Division-Multiplexing System

The inter-carrier interference (ICI) in the no-guard-interval orthogonal frequency-division-multiplexing (NGI-OFDM) system causes severe performance degradation when 2-samples/symbol (Sa/sym) digital signal processing (DSP) is used at the receiver. To enable narrow bandwidth devices and low sampling rate DSP, a novel ICI suppression (ICIS) method is proposed and experimentally demonstrated in this letter. The proposed method improves the performance of the 4-Gbaud 25-carrier NGI-OFDM system by up to 4 dB, and 2-Sa/sym DSP with ICIS achieves comparable performance as the conventional 8-Sa/sym DSP without ICIS, with moderately increased complexity.

Digital nonlinear compensation techniques for high-speed DWDM transmission systems

Nonlinear distortion is one of the major obstacles in DWDM systems with enhanced spectral efficiencies. In this paper several approaches to address the issue of nonlinear impairments by means of digital signal processing are discussed. Firstly, implementation-efficient and novel intra-channel nonlinear compensation schemes are proposed; one is based on digital pre-distortion at the transmitter end and the other is based on digital back-propagation at the receiver end. The virtues of the two approaches and implications to various applications are discussed; the pre-distortion technique is in particular advantageous with QPSK modulation format; on the other hand, the improved version of digital back-propagation is attractive in transceivers with adaptive or variable modulation/demodulation. Second, digital signal processing algorithms to counteract inter-channel nonlinearities, namely cross-phase modulation, are discussed; nonlinear polarization crosstalk canceller (NPCC) is proposed for mitigating the impact of nonlinear-induced fast polarization crosstalk in dual-polarization systems (in the speed beyond MHz), which is too fast to be tracked by ordinary polarization demultiplexing algorithms; improvement to the carrier phase recovery circuit and its combination with NPCC are even more useful for further performance improvement. Numerical and experimental data are introduced to support the above discussions.