---
title: "Optical fiber advantages and labelled diagram"
subject: "Basic Electronics Engineering"
chapter: 5
key: "semester_2/basic_electronics_engineering:optical-fiber-adv-diagram"
source: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/optical-fiber-adv-diagram
site: BCT Engineering
---

# Optical fiber advantages and labelled diagram

Basic Electronics Engineering · Chapter 5: Communication System

- Asked in: 2070 Magh, 3+3 marks
- Video: [Optical Communication - Advantages, Disadvantages and Applications](https://www.youtube.com/watch?v=jqOJ8pBysUI) — Padmasri Naban
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/optical-fiber-adv-diagram
- Whole chapter: https://www.bctengineer.com/md/semester_2/basic_electronics_engineering/chapter-5

## Question

What are the advantages of optical fiber communication system? Draw and label the diagram of optical fiber.

## Short answer

Advantages: very large bandwidth, low loss, immunity to interference, security, small size, no electrical hazard, and abundant raw material. The fiber consists of a high-index core surrounded by a lower-index cladding and a protective jacket.

## Answer

#### Advantages of optical fiber communication

1. Very large bandwidth, giving high data rates and many channels.
2. Very low signal loss (attenuation), so long distances without repeaters.
3. Immune to electromagnetic interference, radio-frequency interference and crosstalk.
4. High security, because it is difficult to tap.
5. Small, light and flexible, so easy to handle and install.
6. No electrical hazard, no sparks or short-circuits.
7. Economical in the long run; raw material (silica) is abundant.

#### Diagram of an optical fiber (labelled)

```text
 Cross-section:                Longitudinal section:

     ___________              +-------------------------+
   /  _________  \            | Outer jacket            |
  /  /  _____  \  \           |+-----------------------+|
 |  |  / core \  |  |         || Cladding (n2)         ||
 |  |  \(n1)  /  |  |         ||+---------------------+||
  \  \ \_____/  /  /          ||| Core (n1 > n2)      |||
   \  \_______/  /            ||+---------------------+||
    \___________/             || Cladding (n2)         ||
  jacket > cladding > core    |+-----------------------+|
                              | Outer jacket            |
                              +-------------------------+
```

- **Core:** central glass strand (8 to 62.5 µm) that carries the light; refractive index n1.
- **Cladding:** glass layer around the core (125 µm) with lower index n2 < n1; it keeps light inside by total internal reflection.
- **Jacket (buffer coating):** plastic layer that protects the fiber from moisture, damage and bending.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the core?
   A. The outer protective layer
   B. The cladding with lower index
   C. The jacket
   D. The central glass strand that carries light, with index n1
   Answer: D. Core size is 8 to 62.5 µm. (Key point: Core)

2. What is the role of cladding?
   A. Protects against moisture
   B. Lower index n2 keeps light inside by total internal reflection
   C. Carries the light
   D. Amplifies the signal
   Answer: B. Cladding has n2 < n1. (Key point: Cladding)

3. What is the jacket?
   A. The glass core
   B. The reflective layer
   C. The light source
   D. A plastic coating that protects from moisture, damage and bending
   Answer: D. It is the outer buffer coating. (Key point: Jacket)

4. Which is an advantage?
   A. Short range
   B. Immune to EMI and crosstalk
   C. Small bandwidth
   D. Easily tapped
   Answer: B. Fiber has high security and low loss. (Key point: Advantage)

## Related in Basic Electronics Engineering

- [Communication system; optical fiber merits](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adefine-comm-optical-merits) — Basic Electronics Engineering, chapter 5
- [Role of antenna; optical fiber pros and cons](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aantenna-role-optical) — Basic Electronics Engineering, chapter 5
- [Optical fiber and its advantages](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aoptical-fiber-advantages) — Basic Electronics Engineering, chapter 5, asked 5×
- [Communication system and block diagram](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Acomm-system-block-diagram) — Basic Electronics Engineering, chapter 5, asked 7×
- [Optical fiber advantages and disadvantages](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aoptical-fiber-adv-disadv) — Basic Electronics Engineering, chapter 5
- [Communication system and AM block diagram](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adefine-comm-am) — Basic Electronics Engineering, chapter 5

## Related in other subjects

- [Elements of optical communication system](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Aoptical-communication-elements) — Propagation and Antenna, chapter 6, asked 3×
- [Optical fiber advantages and disadvantages](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aoptical-fiber-pros-cons) — Instrumentation II, chapter 5
- [Short note: Multi mode optical fiber](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Amultimode-fiber-short-note) — Data Communication, chapter 4
- [Short note: Optical fiber versus STP](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aoptical-fiber-vs-stp) — Data Communication, chapter 4