Fibre optics is the branch of physics pertaining to the passage of light through thin filaments of transparent material and includes transmission theory ,applications and manufacturing technology.Alexander Graham Bell ,the inventor of the telephone is the pioneer in this field.he successfully proved that light is a good signal carrier by transmitted a telephone signal over a 200m using light as the signal carrier in 1880.
The field of light became after the invention of laser in 1960,highly monochromatic ,intense coherent and directional beam .in 1966 K.C.Kao and G.A.Hockhman proposed that fibers with highly purity core surrounded by a cladding of lower refractive index could be used for transmitting light over long distances.
total internal deflection is the main principle behind in fibre optics.if the angle of incidence in the denser mediun is greater than critical angle the incident ray is reflected back into the same medium,totally.this phenomenon is called total internal deflection
there are three types of optical fibers
- step-index single mode
- step-index multimode
- graded-index multimode
in step index single mode ,the core of the optic fibre has a uniform refractive index .the cladding ,surrounding the core has a uniform refractive index that is slightly lower than the refractive index of the core region .In step index multimode ,it has a large core dia as compared to single mode.these fibres are used for conventional image transfer are limited to short distances for information transmission due to pulse broadening.In graded index multimode ,core has a non uniform refractive index varies across the core diameter ,is used to minimize pulse broadening due to intermodal dispersion(here check some videos shows the working of optic fibre.....)
