An optical fiber made of two concentric glass cylinders is illuminated at one en

Question

An optical fiber made of two concentric glass cylinders is illuminated at one end by a
point light source (see figure) placed in air. The inner cylinder (so-called core) has
refractive index n1. The outer cylinder (so-called cladding) has smaller refractive index
n2. The rays emitted by the point source that are accepted in the fiber and travel in the
core by total internal reflection belong to a cone with half-angle ?a (acceptance angle).
a) What is the analytical expression between ?a , n1, and n2 ?
b) What happens to the ray incident at an angle ? > ?a ?
c) Determine sin?a when the core has an index of 1.62 and the cladding 1.52. What would
happen to a ray incident at 45°?

Explanation / Answer

(a) sina (n1 - n2)1/2

(b) Rays that fall within this angular range are reflected from the core-cladding boundary by total internal reflection, and so are confined by the core.

(c) sin a = (1.622 - 1.522)0.5 = 0.56

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.