Question

Relatstep inde fiber has a relative refractive index difference of 0.86

Answer 1

In optical fiber, the total internal reflection of light occurs when the propagation angle, θ, is smaller than the critical angle, θc (total reflection angle). Now we consider propagation light in optical fiber (see Fig.). In Fig., n1, and n2 is the refractive index of the core, and the clad, respectively, and the critical angle, θc, is the incident angle, φ1, at the refration angle of φ2=90 (θ2=0). Snell’s law is expressed as follows;

2.1.1

therefore, the supplementary angle of the critical angle, θc, is defined by the following equation,

2.1.2