PHOTONIC CRYSTAL FIBER

NAGAMALLESWARA RAO VAMSHI PRASAD ANIL KUMAR SURESH PAVAN SANDEEP DATE: 05/06/2009

AIM : To design photonic crystal fiber with ultra flattened dispersion

and loss less fiber by using the three different air hole diameters.

CONTENTS: INTRODUCTION

1.1 structure of PCF 1.2 types of PCF DESIGN

I. ParametersII. Boundary conditionsIII. Properties

CHARACTERISTICSCONCLUSION

INTRODUCTION :

A Photonic crystal (pc) is a periodic arrangement of dielectric materials. pc’s ability to inhibit the propagation of EMwaves (i.e photons) with well defined frequences.

Photonic crystal fiber (PCF) is a new class ofoptical fiber i.e in the cladding region ,numerousair-holes running along the length of the fiber

Λ (pitch)

dsilica

Air - holes

CORE

)22(**)2( claddingcorePCFv

Normalized frequency is given byNormalized frequency is given by

STRUCTURE OF PCF:STRUCTURE OF PCF:

TYPES OF PCF:

1 . High index guiding fibers (SOLID-CORE)

guiding light in solid core by M-TIR principle. 2 . Low index guiding fibers (HOLLOW – CORE)

Guide light by photonic band gap.

Solid-core Holey fiber Hollow – core fiber SOLID CORE

HOLEY CLDDING FORMS EFFECTIVELOW - INDEX MATERIAL

HOLLOW - CORE

AIR - HOLES

DESIGNING PARAMETERS:

1 . Core diameter ( d )2 . Pitch ( Λ )3 . Air – hole diameters Depending up on the type of application we can change

the core material and diameters of the air – holes.

Core material silica or polymersCore material silica or polymers

Dispersion :

)()()( mg DDD

))(

()(),(NB

DNAND gfixedg

M – PITCH RATIOM – PITCH RATIO

N – AIR HOLE DIAMETER RATION – AIR HOLE DIAMETER RATIO

)(0

)(0dd

Geometrical dispersionGeometrical dispersionMaterial dispersionMaterial dispersion

Confinement factor ≡ 1 Confinement factor ≡ 1

The geometerical dispersion can be written as :The geometerical dispersion can be written as :

)(1),(/ M

DM

mD gdfixedg

andand

432)( eNdNcNbNaNA

)()]cos(1[)( 2

NAihNgNNB

Scaling transformations are Scaling transformations are

Where Where a, b , c………….are fitting coefficientsa, b , c………….are fitting coefficients

The The confinement loss confinement loss can be obtained as the imaginarycan be obtained as the imaginaryPart of the mode.Part of the mode.

]Im[686.8 0 effc nKL

Wave vector at free spaceWave vector at free space

1 . For guided modes

2 . For radiative modes

Boundary conditions:

Anisotrpic perfect matched layer(PML)

Perfect electric conductor & perfect magnetic conductor

PCF PROPERTIES :

1 . Number of modes it depend on the v – parameter & density of

states. 2 . Dispersion it relates with wavelength(λ) & group velocity 3 . Nonlinearity it relates with power density.4 . Bending Loses

DispersionDispersion ((ps/nm/km)ps/nm/km)

LOSSLOSS

FLATTENED DISPERSIONFLATTENED DISPERSION

To control the dispersion & loss variation of PCF’s by changingTo control the dispersion & loss variation of PCF’s by changingthe diameter of the different air hole diameters. the diameter of the different air hole diameters.

Number of air holes increases confinement loss decreasesNumber of air holes increases confinement loss decreases

CHARACTERISTTICS:CHARACTERISTTICS:

WavelengthWavelength ( meter)( meter)WavelengthWavelength ( meter)( meter)

((dB/km)x 10-5dB/km)x 10-5

CONCLUSION:CONCLUSION:By the variation of different diameters we can achieve desirable By the variation of different diameters we can achieve desirable Dispersion and loss.Dispersion and loss.

Dispersion variation is D=0.6 (ps/nm/km)Dispersion variation is D=0.6 (ps/nm/km)Loss is 1.6103 (dB/km)x 10-5Loss is 1.6103 (dB/km)x 10-5

in the wavelength range of 1.55 in the wavelength range of 1.55 pm to 1.7 pmpm to 1.7 pm

By the variation of number of air hole rings we can achieveBy the variation of number of air hole rings we can achievedesirable reduction in loss.desirable reduction in loss.

A Novel Design of Photonic Crystal Fiber with Ultra-FlattenedA Novel Design of Photonic Crystal Fiber with Ultra-Flattened

Dispersion and Ultra-Low Loss.Dispersion and Ultra-Low Loss.

Sh.Mohammad Nejad, M. Aliramezani,Sh.Mohammad Nejad, M. Aliramezani,

M. PourmahyabadiM. Pourmahyabadi

BYBY

DATE: 8/08/2008DATE: 8/08/2008

REFERENCE:REFERENCE: