Friday, April 22, 2011

Optical fibers: fiber parameter, diameter, types


Optical fibers: numerical aperture, fiber parameter, transversal modes, mode field diameter, fiber types

optical fiber
Fiber

Light propagation: inner total reflection

optical reflection


How to change the refractive index?

refractive index


How much light we can couple into a fiber?

light in the fiber


Angle of acceptance: φA

"Opening" angle: 2φA

Numerical aperture: NA= n0 sin φA


Stepwise (SI) and gradient (GI) index fibers

SI GI fibers


Transversal modes:

Waves:

transversal modes


Interference in fibers:

interference in fibers


Modes:

modes


Fiber parameter:

fiber parameters


Single mode operation at V ≤ 2.405

Materials for fibers:

Cladding materialCore materialFiber type
SiO2 (Glass)SiO2 (doped) (Glass)MMF, SMF (GOF)
PolymerSiO2 (Glass)MMF (GOF)
PolymerPolymerMMF (POF)


Mode field diameter:

mode field diameter

Mode field diameter for different fiber parameters
-> in SMF a big part of the field propagates in the cladding!




Comments: