Optical Fiber

Introduction

• Optical fiber is used for data transfer.
• It helps in achieving high-speed internet.
• This optical fiber is laid both on land and in the sea.

Physics Concept

• Total Internal Reflection (TIR): When light moves from a denser medium to a rarer medium and the incidence angle is greater than the critical angle, it reflects.
• Due to TIR, data transfers quickly.

Structure of Optical Fiber

• Made of glass, plastic, and fibers.
• Main elements:
  • Core layer
  • Cladding layer
  • Buffer jacket
  • Outer jacket (polymer)
• Silicon coating: Makes the surface 95% reflective.

Working Principle

• When light rays enter the core and the angle of incidence is greater than the critical angle, they reflect.
• These light rays propagate in a zigzag manner.
• In silica glass fiber, up to 95% of light transmits over a distance of 1 km.

Transmission Factors

• High reflective index of core material is essential.
• Angle of incidence should be greater than the critical angle.

Classification

• Based on reflective index:
  1. Step Index Optical Fiber
  2. Graded Index Optical Fiber
• Based on mode:
  1. Mono Mode
  2. Multiple Mode

Step Index Optical Fiber

• Core medium has a uniform refractive index.
• Abrupt change at the interface between core and cladding.
• Output is greater than input.

Graded Index Optical Fiber

• The refractive index of the core decreases in a parabolic form.
• Maximum at the center, decreases towards the edges.

Conclusion

• Covered the working, construction, and classification of optical fiber.
• In the next video, we will discuss the acceptance angle and related numerical problems.