Get Thesis Now !

PROJECT TOPIC:  ACCURATE MODELING FOR THE REDUCTION OF MICRO BEND LOSS THAT WILL BE ESSENTIAL IN THE DESIGN OF OPTICAL FIBERS USED IN COMMUNICATION NETWORKS
Department:  Electrical Electronics
AMOUNT:  20,000
FORMAT:   MS WORD
PAGES:  125
 
Get Complete Work

Abstract Preview

ACCURATE MODELING FOR THE REDUCTION OF MICRO BEND LOSS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     

INTRODUCTION

 

A clear understanding of the fundamental properties of fibers is needed not only to support the current optical networks, but to ensure the development of more powerful networks in the future too. An understanding of fiber optics is also important for the development of the fiber components found not only in communication systems but also in the many types of fiber sensors. Modern optical fiber system design typically requires the use of mathematical numerical computer models to estimate system performance.  The optical signal through transmission it in optical fiber suffers distortions from dispersion and nonlinearities. Dispersion can be avoided by using two optical fiber dispersion-shifted or dispersion-flattened fibers, but effects of nonlinearities remain a limiting factor for long distance transmission.

In last few years optical fibers have progressed from research to practical applications. Optical fibres are essentially utilized to transmit data. It passes the message in the form of light to long distances. Therefore, optical fibers are joined to form a long cable. There may be some losses in the optical fibres while communication. This paper explains about the various types of losses along with its causes and solutions of reducing those losses. The reasons for these losses can be misalignment of the fibers or inhomogenities in the fibre substance, etc. Optical fibers can be utilized as sensors for finding out attributes like pressure, strain, electricity, velocity, temperature, etc. Various factors contribute to the signal loss in optical fibres such as wave guide structure, material composition, preparation or purification method. The losses are divided in to various kinds like material scattering, material absorption, curve and micro bending losses, mode coupling radiation losses, losses due to leaky modes, splice losses or connector losses.

CAUSES OF BENDING LOSSES

·        Due to processing rather than   mishandling.

·        Loss can occur due to distortion of  the core cladding interface,   induced by manufacture or poor  cable design

 

STATEMENT OF PROBLEM

 

It is obvious that bending of optical fibres causes loss of optical power, and reduces its performance.

So the exact modeling of bending loss is very important for designing communication systems and optical instruments. In recent years various fibre bending sensors have been proposed and the bending-type fibre-optic sensors could be used to measure different physical parameters such as voltage, pressure, strain, temperature, etc. Microbending (bending with small radius of curvature) has been studied by some researcher. But irregular small cracks (macrocracks) occur during the manufacture of optical fibres and microbending and this sort of stress (like torsion) would make these cracks bigger and this render the fibre useless (Faustini.1997).

Micro Bend losses are a frequently encountered problem in fiber optics: optical fibers exhibit additional propagation losses when they are bent. Typically, these losses rise very quickly once a certain critical bend radius is reached. This critical radius can be very small (a few millimeters) for fibers with robust guiding characteristics (high numerical aperture), whereas it is much larger (often tens of centimeters) for single-mode fibers with large mode areas.

Generally, bend losses increase strongly for longer wavelengths, although the wavelength dependence is often strongly oscillatory due to interference with light reflected at the cladding/coating boundary, and/or at the outer coating surface(Valiente,1989). The increasing bend losses at longer wavelengths often limit the usable wavelength range of a single-mode fiber. For example, a fiber with a single-mode cut-off wavelength of 800 nm, as is suitable for operation in the 1-μm region, may not be usable at 1500 nm, because they would exhibit excessive bend losses. Note that even without macroscopic bending of a fiber, bend losses can occur as a result of microbends, i.e., microscopic disturbances in the fiber, which can be caused by imperfect fabrication conditions.

AIM OF THIS WORK

The purpose of this work is to:

1.     To Analyze, design and enhance optical fiber to reduce the attenuation and distortion in fiber optics, By using mathematical model and computer simulations for multi-layer optical fibers with various constructed layers which help to explain the characteristics of such optical fibers.

2.     To determine the accurate modeling for the reduction of micro bend loss that will be essential in the design of optical fibres used in communication networks.

3.     To determine the Performance evaluation of transmission properties and Investigate the effects of nonlinearity due to Kerr effect on parameters design of fiber optics.

4.     To compare the various methods of reducing micro bending losses in fibre optics communication network.

Download