Based on the polarization vector propagation equation of stimulated Brillouin scattering (SBS) nonlinear effects in fibers, we find the spectral polarization spreading behavior in SBS. As a signal light propagates along a fiber, the state of polarization of different frequency components of the signal light will experience different polarization pulling forces from the counter propagating pump light, resulting in a nearly circular symmetry of spectral spreading of the polarization state at the output end of fiber. Through theoretical analysis and simulation, this paper studies the SBS spectrum polarization spreading effects in the cases of ideal single mode fiber(SMF), practical SMF, and polarization maintaining fiber (PMF). Finally, we demonstrate the SBS spectrum polarization spreading effect in a 200m SMF and a 140m PMF experimentally and good agreement with theory is found.
A one-degree of freedom (DOF) tunable single fiber ring depolarizer is proposed by setting the bend-induced birefringence in the fiber ring specially to behave as a half-wave plate (HWP) and with the optimal coupling ratio of the coupler. Depolarization can be realized by just rotating the fiber ring. The methods of making and testing the HWPperformance of the fiber ring are analyzed and discussed. A 12-meter long fiber ring depolarizer is demonstrated to depolarize a Fabry-Perot (FP) laser with 10-meter coherent length. Degree of polarization (DOP) of 1.5% can be reached by rotating the whole set of fiber ring. Moreover, if a polarizer ahead of the fiber ring is inserted, a full scale one degree of freedom tunable depolarizer can be realized.
In this paper, a degree of polarization (DOP) tunable single-mode fiber ring depolarizer is proposed and demonstrated.
The fiber ring is made of a 2×2 coupler and a piece of single-mode fiber delay line, which is wound into a coil
performing as a half-wave plate. For a random input state of polarization, the full depolarization can be realized by
rotating the whole set of fiber ring through a proper angle, and for a linearly-polarized input light, the output DOP can
change from one to zero. In our experiment for a fiber ring with a delay line of 10 meters, a Fabry-Perot (FP) laser with
8-meter coherent length is depolarized with a DOP less than 1%.
A dynamic depolarized light based on the polarization chaos is generated from a SOA-based fiber ring laser experimentally. And also a theoretical model is developed to analyze the experiment phenomenon. By simulation, it is revealed that the polarization dependency in the fiber cavity can cause polarization chaos just as the anisotropy within SOA does, and the numerical results consist well with the experiment results. With the polarization chaos, we have obtained a dynamically depolarized light with a low dynamical DOP less than 3% and with polarization changing rate as high as about several million Hertz.
An optical secure communication system based on digital chaos and Polarization Shift Keying (PolSK) technology is
proposed. In several selected PolSK schemes, states of polarization are partially or totally uniform on Poincare sphere.
Different PolSK schemes are chosen according to the real-time chaos-based pseudo-random sequences to modulate
original information in different periods of clock of the transmitter. In the receiver, according to the synchronous chaotic
sequences, corresponding PolSK schemes are used to demodulate the information. Simulation is carried out by using the
softwares of OptiSystem and Matlab. Some analysis results are presented. In the conclusion, this system works well in
communication and has strong anti-attack capacity.
The CSO (composite second-order distortion) induced by self-phase modulation (SPM) in an AM-VSB externally modulated CATV system which employs optical fiber Raman amplifiers (FRA) is studied theoretically in this paper. Firstly, the analysis of CSO is achieved by solving Schrödinger equation using perturbation method. And then numerical results are presented and discussed. According to the study in the paper, the SPM induced CSO performance can be improved by more than 10 dB by using FRA than using EDFA in CATV systems.
Many network architectures have been designed for the future high capacity transmission. Hybrid Opto-electronic Ring NETwork (HORNET), a kind of IP/WDM metro network, is one of them. The inherent defects in WDM network, like unfairness and low efficient, are conquered by using Distributed Queue Bidirectional Ring (DQBR). But that way with a high complexity is difficult to be realized both in hardware and software. In this paper, a modified Round Robin scheme, called Simple Round Robin (SRR) with configuration is proposed and simulated in HORNET. Round Robin is a comprehensively researched method to solve the unfairness, and with low complexity, but much low efficient. SRR aims to realize the fairness control, and achieve a high throughput with accurately designing and initializing as well. It seems satisfactory that SRR with config does well both in fairness and efficiency.
A novel two home-wavelengths Round-Robin (THWRR) wavelength assignment scheme is proposed to achieve data delivery fairness for a slotted IP/WDM metro ring. According to our simulation, THWRR works well on achieving traffic delivery fairness across all access nodes in the ring. Furthermore, when working together with an additional fixed-tuned transmitter, THWRR is able to gain significant improvement both on fairness and delivery capacity.
A graphical simulation system for the study of the physical performance of optical packet switching (OPS) nodes is accomplished. With the simulation system, the effect on bit error rate (BER) performance caused by a variety of factors, such as the crosstalk parameters of OPS nodes, numbers of cascaded OPS nodes, the length of optical output buffer, the traffic load, the amplitude fluctuation and the delay fluctuation of optical signals, are simulated and studied. The reliability of the simulation system is proved by the agreement between simulation results and analytical results
Two optical packet switching metropolitan area networks are introduced. They adopt different ring architectures and related media access control protocols. Their simulation system is set up to study both their physical and logical characteristics. Simulation system adopts self-similar traffic that has been demonstrated to accord to real traffic. This simulation system can layout the MAN with optimized network architecture, node scale, wavelength multiplexing number and system physical and logical response parameters according to the design requirements including bandwidth, QOS, traffic load and so on.
A setup used for measuring the polarization modal dispersion of a polarization-maintaining fiber is arranged. The measurement has high accuracy (<1%) and large dynamic range (0.1 ps to 103 ps). By using this setup, the mode-coupling parameter of polarization-maintaining fiber is also accurately measured.
The alignment of principal axes between birefringent fibers by the spatial technique is investigated theoretically and experimentally. It is shown that the distribution-sensing effect of the method has potential application in optical fiber and cable measurement.