Xiaoli Yin

Physical secure enhancement in optical OFDMA-PON based on two-dimensional scrambling

This paper proposes a novel physical-enhanced chaotic secure strategy for optical OFDMA-PON based on two-dimentional scrambling. A 15.6-Gb/s encrypted 64QAM-OFDM data has been successfully demonstrated in the experiment.

A novel ECDM-OFDM-PON architecture for next-generation optical access network

This paper proposes a novel ECDM-OFDM-PON architecture for next-generation passive optical network. An error free bidirectional transmission of two PON channels has been successfully demonstrated in the experiment.

Optical frequency comb generation using two cascaded polarization modulators

A novel approach to generate the flattened optical frequency comb (OFC) with tunable frequency spacing is proposed. The proposed generator consists of two cascaded polarization modulators driven by two radio frequency signals with different frequencies. By adjusting the parameters, 9, 12, and 16 comb lines can be generated with tunable frequency spacing. The scheme requires no DC bias voltage of the modulators and no optical filter, which makes our method simple and stable. A concept proof simulation is conducted to confirm the feasibility of the generation schemes of the 9-, 12-, and 16-line OFCs.

MIMO signal processing for mode division multiplexing with RLSCMA algorithm

We numerically simulate the influence of mode coupling and modal delay on the transmitted signal. Then we carry out adaptive signal processing with MIMO equalizers based on recursive least squares constant modulus algorithm (RLSCMA). The simulation results show that the distorted signals are restored efficiently with fast convergence speed.

A new method of calculating the orbital angular momentum spectra of Laguerre–Gaussian beams in channels with atmospheric turbulence

Studying orbital angular momentum (OAM) spectra is important for analyzing crosstalk in free-space optical (FSO) communication systems. This work offers a new method of simplifying the expressions for the OAM spectra of Laguerre–Gaussian (LG) beams under both weak/medium and strong atmospheric turbulences. We propose fixing the radius to the extreme point of the intensity distribution, review the expression for the OAM spectrum under weak/medium turbulence, derive the OAM spectrum expression for an LG beam under strong turbulence, and simplify both of them to concise forms. Then, we investigate the accuracy of the simplified expressions through simulations. We find that the simplified expressions permit accurate calculation of the OAM spectrum for large transmitted OAM numbers under any type of turbulence. Finally, we use the simplified expressions to analytically address the broadening of the OAM spectrum caused by atmospheric turbulence. This work should contribute to the concise theoretical derivation of analytical expressions for OAM channel matrices for FSO-OAM communications and the analytical study of the laws governing OAM spectra.

Design of multi-pumped Raman fiber amplifier by differential evolution optimization

A new method to optimize the gain spectrum of a multi-pumped fibre Raman amplifier (FRA) is proposed, based on differential evolution algorithm (DE). In this method, when the wavelengths of the signals, the number of the pumps, the number of iterations and the range of pump wavelength and power are given in advance, it is possible to get an optimized gain spectrum. With two pumps in FRA, we can get a flat gain spectrum, whose gain ripple is 1.6dB and range is from 1530nm to 1558nm, by using this method.

Simulation of Third-Order Intermodulation Distortion Suppression Incorporating Dual-Parallel Mach–Zehnder Modulator in a CR-SSB Modulation

ABSTRACT A novel scheme is proposed to enlarge the spurious free dynamic range (SFDR) of microwave photonic (MWP) link by using dual-parallel Mach–Zehnder modulator, which modifies the single sideband signal and replaces the optical carrier with an unmodulated one to remove the optical main sources of third-order intermodulation distortion (IMD3). Simulation results show that the IMD3 and fifth-order intermodulation distortion can be suppressed greatly even when the modulation depth increases to a high value, and the link is limited by seventh-order intermodulation distortion and the SFDR is improved by 34.2 dB Hz in a 1-Hz bandwidth. The error vector magnitude of the MWP link with the proposed scheme is improved significantly for the transmitted 1-Gbit/s 16- quadrature amplitude modulation (QAM) signal.

Modified algorithm for calculating the center position of optical vortices in the space optical communication system

The fine tracking system is important to improve the performance of orbital angular momentum (OAM) space optical communication system. In order to improve the accuracy and stability of the centroid algorithm, this article proposes a modified algorithm to detect the center position of OAM light beam. The modified algorithm firstly takes a binary-conversion with the threshold based on the intensity profile of OAM beam, and then calculates the center position of the light spot using centroid algorithm. The threshold for binary-conversion of Laguerre-Gaussian (LG) beam is obtained by theoretical analysis and numerical calculation. The accuracy, stability and complexity of the modified algorithm are studied by numerical simulation. The results show that the new algorithm, compared with the centroid algorithm, has 2 orders of magnitude higher in computing accuracy and 3∼4 orders of magnitude higher in stability. However, the computing time has increased by about 1.5 times compared with the centroid algorithm.

Polarization Mode Dispersion monitoring for phase-modulated optical signals utilizing parallel cross-phase modulation in a highly nonlinear fiber

We propose a first-order Polarization Mode Dispersion (PMD) monitoring technique for phase-modulated optical signals utilizing the cross-phase modulation (XPM) effect between the input signal and the inserted continuous-wave probe in parallel connection. Because of accumulation of PMD, the XPM effect in nonlinear fiber leads to variation of pump phase. This can cause spectrum broadening resulting in variation of pump power. The technique can suppress the influence of PMD in one branch of the two signals in parallel connection then use the difference of the two pump power at the same band to monitor PMD. The simulation shows that the technique can monitor PMD of 40-Gb/s non-return-to-zero differential quadrature phase-shift keying (NRZ-DQPSK) from 0–30ps.The dynamic range over 3dB can be used in accurate monitoring compared to existing methods. The applicability of this monitoring technique to higher bit-rate phase-modulated signals, such as 80-Gb/s NRZ-DQPSK, is also investigated via simulation.

A Software Defined Radio Access Network based on inter-cell interference suppression

The convergence of optical and wireless network has led to the trend of future access network . Under the study of Software Defined Radio Access Network(SD-RA) and Soft Frequency Reuse(SFR) system model, this paper presents a new inter-cell interference suppression algorithm of SD-RA network. The paper also summarizes and analyses the difference between the SFR based on coordinate multi-point transmission (CoMP) and SD-RA. The computer simulation results show that the inter-cell interference suppression algorithm can bring about 5dB SINR (Signal to Interference plus Noise Ratio) gain.