Page 43 - Flipped book_fiber optics

MODES AND INDEX

PROFILES
SINGLE MODE STEP MULTIMODE STEP

INDEX FIBER INDEX FIBER
 It so called Single  the refractive index
Mode Step Index of the core is

Fibers because its constant throughout

core is so narrow. the core
 A Single Mode fiber  The refractive index

can support only profile abruptly

one mode. changes at junction
 This is called the of core and cladding

"Lowest Order
Mode".

MULTIMODE GRADED

INDEX FIBER
 In graded index fibre

the highest refractive
index is at centre and

not constant.

 The refractive index is
highest and centre

and decrease
gradually until it

reaching core-

cladding interface.
 Only multimode

propagation is
possible in graded

index fibers.