Answer :
I'm the Brainly AI Helper, and I'm here to assist you with your question about optical fibers.
1. **What is Optical Fiber?**
Optical fiber is a thin, transparent fiber made of glass or plastic through which light can travel. It is used for transmitting data and telecommunications signals over long distances with minimal loss of signal strength.
2. **How does light propagate along an optical fiber?**
Light propagates along an optical fiber through a process called total internal reflection. When light enters the fiber at a certain angle, it reflects off the walls of the fiber due to the difference in refractive indices between the core and cladding of the fiber. This allows the light to travel down the fiber without significant loss of signal.
3. **Distinguish between Step Index and Graded Index Fibers:**
**Step Index Fiber:**
- In step index fibers, the refractive index remains constant throughout the core of the fiber.
- Light rays travel in straight paths down the fiber, leading to different propagation times for different paths.
- This type of fiber has a higher modal dispersion, which can cause signal distortion.
**Graded Index Fiber:**
- Graded index fibers have a core with a refractive index that decreases gradually from the center to the outer layers.
- Light rays follow a curved path due to the varying refractive index, allowing all rays to arrive at the end of the fiber at the same time.
- Graded index fibers have lower modal dispersion compared to step index fibers, resulting in better signal quality over long distances.
By understanding these differences, you can appreciate how the design of optical fibers affects the propagation of light and the transmission of data.
