Increasing the system capacity and spectral efficiency(SE)per unit bandwidth is one of the ultimate goals for data network designers,especially when using technologies compatible with current embedded fiber infrastructures.Among these,the polarizationdivision-multiplexing(PDM)scheme,which supports two independent data channels on a single wavelength with orthogonal polarization states,has become a standard one in most state-of-art telecommunication systems.Currently,however,only two polarization states(that is,PDM)can be used,setting a barrier for further SE improvement.Assisted by coherent detection and digital signal processing,we propose and experimentally demonstrate a scheme for pseudo-PDM of four states(PPDM-4)by manipulation of four linearly polarized data channels with the same wavelength.Without any modification of the fiber link,we successfully transmit a 100-Gb s−1 PPDM-4 differential-phase-shift-keying signal over a 150-km single-mode fiber link.Such a method is expected to open new possibilities to fully explore the use of polarization freedom for capacity and SE improvement over existing fiber systems.
Zhi-Yu ChenLian-Shan YanYan PanLin JiangAn-Lin YiWei PanBin Luo
we demonstrate the adjustability of optimal input power(OIP) of the radio over fiber(RoF) link by proper link gain control in the central unit(CU) and remote antenna unit(RAU).The experiment results show that the reading and writing distance(RWD)of the radio frequency identification(RFID)service and the throughput of the WiFi service have a max increase of 3cm and 6.975Mbit/s respectively when the OIP value equals to output power of commercial products,compared with OIP value with 5-dBm right/left shift to the output power.
We propose the configuration of signal multiplexing with four polarization states and investigate its transmission performance over single-mode fiber links.Using coherent detection and digital signal processing,a demodulation scheme for four-polarization-multiplexed(4PM)system is presented.We discuss the impact of crosstalk from polarization mode dispersion and polarization beam splitter misalignment on the proposed 4PM system.Furthermore,the transmission distance could be doubled to*50 km by employing feedback decision equalizers.
An adaptive digital backward propagation(ADBP) algorithm is proposed and experimentally demonstrated based on the variance of the intensity noise. The proposed algorithm can self-determine the unknown nonlinear coefficient γ and the nonlinear compensation parameter ξ. Compared to the scheme based on the variance of phase noise, the proposed algorithm can avoid the repeated frequency offset compensation and carrier phase recovery. The simulation results show that the system's performance compensated by the proposed method is comparable to conventional ADBP schemes. The performance of the proposed algorithm is simulated in40/112 Gb/s polarization-division multiplexing(PDM)-quadrature phase-shift keying(QPSK) and 224 Gb/s PDM-16-quadrature amplitude modulation(QAM) systems and further experimentally verified in a 40 Gb/s PDM-QPSK coherent optical communication system over a 720 km single-mode fiber.
Microwave photonic signal generation schemes based on the frequency to time mapping and external modulation are reviewed.We concentrate on those configurations that can provide tunability of frequency,phase of signal,modulation formats(i.e.,2PSK,2FSK,etc.),as well as pulse shapes(i.e.,UWBs-,triangle-and arbitraryshaped,etc.).
Hengyun JiangLianshan YanJia YeWei PanBin LuoXihua Zou
