This paper proposes a kind of modulation architecture for wavelength-division-multiplexing passive optical network （WDM- PON） employing optical differentia/quadrature phase shift keying （DQPSK） downstream signals and two different modulation formats of re-modulated upstream signals. At the optical line terminal （OLT）, 10 Gbit/s signal is modulated with DQPSK. At the optical network unit （ONU）, part of the downstream signal is re-modulated with on-offkeying （0OK） or inverse-return-to-zero （IRZ）. Simulation results show the impact on the system employing NRZ, RZ and carrier-suppressed return-to-zero （CSRZ）. The analyses also reflect that the architecture can restrain chromatic dispersion and channel crosstalk, which makes it the best architecture of access network in the future.
In this paper, a new millimeter-wave （mm-wave） wavelength division multiplexing （WDM） system based on radio-over- fiber （ROF） technology is proposed. In this approach a multi-wavelength light source is obtained by supercontinuum （SC） technique, and mm-wave signals are obtained by using optical heterodyning method. We experimentally demonstrate the generation of optical carriers for 6-WDM channels, obtain 40 GHz ram-wave signals by employing optical heterodyne technique, and successfully achieve low error rate transmission of 2.5 Gbit/s in WDM channels over a distance of 25 km in a G.652 fiber. The experimental results verify that the proposed solution is feasible and cost effective.
A theoretical model of the refractive index changes of the TE and TM modes in an electro-absorption modulator （EAM） is deduced. The photon absorption and refractive index changes are analyzed numerically. The influence of pump intensity on the phase difference between the TE and TM modes is studied. The polarization rotation effect is obtained in the EAM, and a novel all-optical fiber loop buffer is designed.
We describe an all-optical wavelength conversion scheme for 1310 nm to 1550 nm based on nonlinear polarization rotation in a gain-transparent semiconductor optical amplifier （GT-SOA） which brings in the assistant light to improve the property of the converted light. From the SOA carder density equations, the 1310 nm-to-1550 nm wavelength conversion scheme is analyzed by the Jones matrix. The phase shift between TE and TM modes and the converted light are simulated at bit rate of 30 Gbit/s. We also analyze the influence of the input signal power, the injected current and the assistant light power on the extinction ratio of the converted li~,ht.
The principle of a novel orthogonal modulation format of differential 8-1evel phase-shift keying amplitude-shift keying （D8PSK/ASK） with differential bi-phase encoding （DBC） is introduced. Based on it, an optical labeling scheme, in which the payload is 100 Gbit/s D8PSK signal and the label is 10 Gbit/s DBC-ASK signal, is proposed and simulated. The results arc compared with other current schemes, and the effects of transmission range, modulation extinction ratio （ER） and received power on system performance are analyzed, respectively. The results show that the spectrum efficiency and bit error rate （BER） are improved greatly, and when the modulation ER is increased to 11 dB, the balanced performance between the payload and label is achieved.
We experimentally demonstrate and analyze a 10 Gbit/s full duplex wavelength division multiplexing passive optical net- work （WDM-PON） system. A non-return-to-zero differential phase shift keying （NRZ-DPSK） modulation technique is first utilized for downlink direction, and then the downlink signal is re-modulated for the uplink direction using intensity modulation technique of on-off keying （0OK） with a data rate of 10 Gbit/s per channel. An effective colorless WDM-PON full duplex transmission system is achieved for the data rate of 10 Gbit/s per channel with a channel spacing of 60 GHz over the distance of 25 km with low power penalty.
In order to achieve higher spectral efficiency, mode division multiplexing (MDM) in few-mode fibers is a new research area. The idea faces lots of technical issues including intermodal delay and mode coupling which limit the achievable length of the system. This paper is designated to complete the analysis of intermodal delay in step-index few-mode fibers. We analyze numerically all the parameters of fiber, which could impact intermodal delay in few-mode fibers and identify the conditions which can increase the number of multiplex modes without significant increase in maximum intermodal delay.
Abid Munir忻向军刘博Abdul LatifAftab HussainShahab Ahmad Niazi
We propose an arrayed waveguide grating(AWG)-based 10 Gbit/s per channel full duplex wavelength division multiplexing passive optical network(WDM-PON).A chirp managed directly modulated laser with return-to-zero(RZ) differential phase shift keying(DPSK) modulation technique is utilized for downlink(DL) direction,and then the downlink signal is re-modulated for the uplink(UL) direction using intensity modulation technique with the data rate of 10 Gbit/s per channel.A successful WDM-PON transmission operation with the data rate of 10 Gbit/s per channel over a distance of 25 km without any optical amplification or dispersion compensation is demonstrated with low power penalty.
Abdul Latif余重秀忻向军Aftab HusainAshiq HussainAbid MunirYousaf Khan
The performance of colorless wavelength-division multiplexed passive optical network(WDM-PON) systems suffers from the transmission impairments mainly due to Rayleigh backscattering(RB).In this paper,we propose and demonstrate a single fiber colorless WDM-PON which enhances the tolerance to RB induced noise.The high extinction ratio in both return-to-zero(RZ)-shaped differential phase shift keying(DPSK) downstream(DS) data signal and intensity-remodulated upstream(US) data signal helps to improve the tolerance to RB induced noise.Simulation results show that downstream and upstream signals can achieve error-free performance at 10 Gbit/s with negligible penalty and improve the tolerance to RB induced noise over 25 km standard single-mode fiber.
