Optical Fiber Waveguides

SYED AHSAN RAZA

Overview of ContentsIntroduction

Ray Theory Transmission

Electromagnetic Mode Theory for Optical Propagation

Cylindrical Fiber

Single Mode Fibers

Introduction-Optical WaveguidesPhysical structure that guides electromagnetic waves in

optical spectrum

Optical Fibers

Rectangular Waveguides

Introduction-Classification of Optical Waveguides

Classification by GeometryPlanarStrip

Classification by Mode StructureSingle ModeMulti Mode

Classification by Refractive Index DistributionStep IndexGradient Index

Purification of Materials in Optical Fiber

Proposals by Kao and Hockham in 1966 to utilize Optical Fiber as communication medium (Loss>1000 dB/km)

Conventional glass refining techniques used to bring optical fibers losses down to 4.2 dB/km

Further research in glass refining processes allowed fiber manufacturing with losses below 1dB/km(Operation in 0.8-0.9 μm)

Reduced signal dispersion and lower losses found in operation at longer wavelengths (1.1-1.6 μm)

At 1.55 μm high performance fibers exhibited losses to the tune of 0.2 dB/km

Total Internal Reflection

Total Internal Reflection

Snell’s Law of Refraction

Transmission of light in Optical Fiber

Acceptance Angle

Maximum angle to the axis at which light may enter the fiber in order to be propagated

For a fiber with regular cross section, an incident meridional ray greater than the critical angle will continue to be reflected and transmitted inside the fiber

Acceptance Angle

Numerical ApertureProvides the relationship between

CoreCladdingAir

Numerical Aperture

Numerical Aperture

Numerical Aperture