Transmission Characteristics Of Optical Fibers Research Articles

Variable Aperture Technique for Measuring Mode Field Diameters Corresponding to Laguerre Gaussian Spot Size of Higher-Order Modes of Few-Mode Fibers

The mode field diameter (MFD) is an essential parameter for understanding the transmission characteristics of optical fibers. A variable aperture (VA) technique is a standard test method for measuring the MFD of single-mode fibers. Unfortunately, the conventional one cannot measure the MFDs of some higher-order modes correctly because its measurement procedure is standardized for measuring the MFD of the fundamental mode. The conventional VA technique aligns the position of the optical fiber through a peak intensity search on the premise that the fundamental mode, whose intensity is maximum at the beam center, is measured. How to align the position of the optical fiber when measuring the MFD of higher-order modes has not yet been investigated. In this paper, we describe the principle and formulas based on the VA technique for measuring the MFD of a given higher-order mode in few-mode fibers (FMFs). Then, we propose a novel procedure for measuring the MFDs of FMFs. The test apparatus of our technique is almost the same as that of the conventional VA technique except for the use of a mode selective coupler. One can measure the MFDs of arbitrary modes in FMFs correctly by adjusting the position of the fiber under test using the fundamental mode before starting the measurement. Proof-of-principle experiments were performed for three kinds of FMFs, and the experimental results showed that our procedure is useful for characterizing the MFD of each mode.

Efficient Virtual Network Embedding of Cloud-Based Data Center Networks into Optical Networks

The demand for data center bandwidth has exploded due to the continuous development of cloud computing, causing the use of network resources close to saturation. Optical network has become an encouraging technology for many burgeoning networks and parallel/distributed computing applications because of its huge bandwidth. This article focuses on efficient embedding of data centers into optical networks, which aims to reduce complexity of the network topology by using the parallel transmission characteristics of optical fiber. We first present a novel virtual network embedding (VNE) mathematical model used for optical data center networks. Then we derive a priority of location VNE algorithm according to node proximity sensing and path comprehensive evaluation. Furthermore, we propose routing and wavelength assignment for DCNs into optical networks, and identify the lower bound of the required number of wavelengths. Extensive evaluations show that the proposed embedding algorithm can reduce the average waiting time of virtual network requests by 20 percent, increase the request acceptance rate and revenue-overhead ratio by 13 percent, as compared to the latest VNE algorithm.

Design of a novel photonic crystal fiber filter based on gold-coated and elliptical air holes

In recent years, photonic crystal fibers have played an important role in the field of optical communications, and the addition of metal materials to photonic crystal fibers have offered new ways to improve the transmission characteristics of optical fibers. We design a new type of gold-coated photonic crystal filter, which utilizes the surface plasmon resonance effect, and study it by using the finite element method. In this paper, we optimise the structure parameters and analyze the numerical results. The numerical results show that the thickness of metal layer and the air holes near the fiber core strongly affect the performance of the polarization filter. For the operating wavelength of 1550 nm, the loss in the y-polarization direction can be as high as 906.9 dB/cm, which is much larger than the x-polarization direction. When the fiber length is longer than 100 μm, the crosstalk in the wavelength range from 1.4 μm to 1.9 μm is greater than 20 dB. The proposed optical fiber can find application as an optical fiber polarization filter.

Experimental research on the dispersion property of hollow core photonic bandgap fiber

Due to the unique optical properties of low loss, low nonlinearity, high threshold and low latency, hollow core bandgap fibers are endowed with high expectations in the field of high power delivery, optical fiber communication, nonlinear optics, fiber sensors, etc. Fiber dispersion, as one of the basic transmission characteristics of optical fiber, makes the light pulse broadened during transmission, thus has adverse effects on high power pulse transmission system and high speed optical communication system. Therefore, it is significant to study the dispersion characteristics of the hollow core bandgap fiber for its applications in the field of high power pulse transmission and high speed communications. Because of the simple structure of measurement system, low cost, high accuracy and relatively short length of fiber (just needing a few meters long), interferometric technique is suitable for dispersion measurement of hollow core photonic bandgap fiber. The key to obtaining the dispersion results with interferometric technique is the phase extractiton from the interferogram. In order to meet the requirements of hollow core bandgap fiber for wide bandwidth, high efficiency and high accuracy dispersion measurement, a novel phase extraction method based on interferometry is proposed in this paper, by which the precision of dispersion measurement is improved through using the whole data-set in the interferogram. Combining with the determinations of the peak and center of symmetry points, the extraction of phase information can be implemented directly from the interferogram. The experimental results of measuring a standard single mode fiber indicate that the difference between the experimental measurement and theoretical simulation is just 0.6 psnm-1km-1, which proves that this proposed method possesses high accuracy and is suitable for the measurement of hollow core bandgap fiber. Consequently, according to the proposed phase extraction method, the measurement system based on Mach-Zehnder interferometer is set up and the dispersion measurement of a 19 cell hollow core bandgap fiber with a core diameter of 26 m is carried out. Experimental results indicate that the fundamental mode dispersion curve of the 19 cell hollow core photonic bandgap fiber in a wavelength range from 1400 nm to 1630 nm can be obtained. Moreover, four high order mode dispersion curves are obtained for the first time. The measurement results are in accordance with the simulation results. These findings are of significant importance for exploring the dispersion characteristics of hollow core photonic bandgap fibers, and also conducible to their applications in the fields of high power laser delivery, high capacity data communications, optical fiber nonlinear, etc.

Fiber Optic Condition Monitoring during a Full Scale Destructive Bridge Test

Fiber optic sensors were used to monitor structural parameters during a destructive bridge test. A system composed of four different types of fiber optic sensors was used to demonstrate versatility and possible completeness for these type of measurements using fiber optic sensors. The fiber optic sensors were monitored continuously during the test using a single control unit. Local strain measurements on the reinforcing bars were conducted using fiber optic Bragg grating sensors. A new technique employing both current and temperature tuning of a DFB (Distributed Feedback) laser to interrogate gratings was developed, showing good correspondence with resistance strain gauges. This sensor conducted the only strain measurements during and after the failure of the bridge, since all expensive control electronics could be operated from a safe distance. A Bragg grating laser sensor system was also used, with a laser cavity of 40 m using standard connectors. The system was well behaved and the measurements corresponded well with resistance strain gauges. A fiber optic polarimetric sensor measured displacements over 2.5 m at the bridge surface. The measurements were comparable to conventional extensiometer measurements at the same location. Cracking of the bridge surface was monitored by studying reflection and transmission characteristics of optical fibers glued to the surface. Although less cracking occurred than was expected, both transmission loss and OTDR (Optical Time Domain Reflectometry) reflection measurements successfully detected cracking of the bridge surface. The most severe practical problem was unintentional fiber breaks caused by personnel not accustomed to using fiber optics.

Optical Fiber Communications: Principles and Practice

Preface Glossary of symbols and abbreviations 1. Introduction 2. Optical fiber waveguides 3. Transmission characteristics of optical fibers 4. Optical fibers and cables 5. Optical fiber connection: joints and couplers 6. Optical sources 1: the laser 7. Optical sources 2: the light emitting diode 8. Optical detectors 9. Direct detection receiver performance considerations 10. Optical amplification and integrated optics 11. Integrated Optics and Photonics 12. Optical fiber systems 1: intensity modulation/direct detection 13. Optical Fiber Systems 2: coherent and phase modulated 14. Optical fiber measurements 15. Optical Networks Appendix A The field relations in a planar guide Appendix B Gaussian pulse response Appendix C Variance of a random variable Appendix D Variance of the sum of independent random variables Appendix E Closed loop transfer function for the transimpedance amplifier Index

Polarization transmission characteristics of optical fibers with elliptical cross section

AbstractIn the transmission via optical fibers connected to laser diodes, optical switches, optical filters, etc., or in high‐sensitivity high‐selectivity optical heterodyne detection system, polarization characteristics become important in addition to transmission loss and dispersion. The polarization transmission characteristics of optical fibers with elliptic cross‐section are calculated by characteristic matrix method for large values of ellipticity. For two orthogonal polarization modes (oHE11 and eHE11 modes) the transmission velocity, group velocity and their difference (elliptic double refraction) are obtained. The group delay difference among modes is very small but elliptic double refraction greatly affects the polarization characteristics.

Fiber optics in japan

Abstract This paper describes the recent progress in research and development of fiber optics in Japan. A review is presented of recent developments in fiber manufacturing, cabling, and fiber splicing. Experimental results are given for an optical communication system with optoelectronic components. Theoretical analysis and fundamental experiments are not included, nor are research activities in such devices as lasers or in such applications as those in medical fields. Transmission characteristics of optical fibers—in particular loss and pulse spreading—are assessed from the viewpoint of their structures. Various methods of fiber strengthening and structuring cables are described from the viewpoint of mechanical strength. Coupling efficiencies of detachable connectors and methods of permanent fiber splicing are described. Experimental results on optical fiber communication systems are presented and coupling techniques between a light source and an optical fiber are described.