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Optical Fiber Types and Properties
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Optical Fiber Types and Properties
Optical Fiber Types and Properties
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1
Question
What is the primary characteristic of Single Mode Fiber (SMF)?
Answer
Supports a single light path (mode) with high bandwidth and long-distance capability.
2
Question
What core diameter is typical for a SMF?
Answer
Approximately 8–10 microns.
3
Question
Why is SMF suitable for long-distance communication?
Answer
Minimal modal dispersion.
4
Question
What wavelengths are commonly used with mono-mode fiber to minimize attenuation?
Answer
1310 nm and 1550 nm.
5
Question
What light source is typically used with SMF to produce a narrow beam?
Answer
Laser diode.
6
Question
Name two advantages of single-mode fiber.
Answer
Eliminates modal dispersion; high bandwidth.
7
Question
Name two disadvantages of single-mode fiber connections.
Answer
Expensive connectors; precise alignment required.
8
Question
What is step index fiber characterized by in terms of core refractive index?
Answer
Uniform core refractive index with a sudden drop at the cladding interface.
9
Question
Describe the light path in step index multimode fiber.
Answer
Zig-zag path due to multiple total internal reflections.
10
Question
What is modal dispersion and which fiber type experiences it more?
Answer
Pulse broadening due to different path lengths; more in multimode fibers.
11
Question
What materials can be used for step index fibers?
Answer
Glass or plastic cores.
12
Question
Where are step index fibers commonly applied for networks?
Answer
LANs and short-haul data links.
13
Question
Compare step index and graded index fibers in terms of index change.
Answer
Step index: abrupt; graded index: gradual.
14
Question
What is the approximate bandwidth for step index multimode fibers?
Answer
About 20 MHz·km.
15
Question
What is the approximate bandwidth for graded index multimode fibers?
Answer
About 200 MHz·km.
16
Question
What is acceptance angle in optical fibers?
Answer
Maximum angle at which light can enter the fiber and be guided.
17
Question
What is the formula for numerical aperture (NA) of a fiber?
Answer
NA = sqrt(n_core^2 - n_clad^2).
18
Question
What is the relationship between acceptance angle and NA?
Answer
θa = arcsin(NA).
19
Question
What does a higher NA imply for fiber coupling?
Answer
Larger acceptance cone; easier coupling.
20
Question
What is meant by ‘acceptance angle max’ in practice?
Answer
Largest entry angle for light to be guided.
21
Question
What are common advantages of simplex cables?
Answer
Low cost, lightweight, simple routing.
22
Question
What path do light rays take in step index fiber due to total internal reflection?
Answer
Zigzag path
23
Question
Can step index fiber support multiple modes?
Answer
Yes, supports single and multi-mode
24
Question
What is the principal drawback of graded index fiber compared to step index for dispersion?
Answer
Generally lower dispersion in graded index
25
Question
What is the core diameter range for MMF mentioned?
Answer
Approximately 50-62.5 microns
26
Question
What is a major dispersion issue in MMF?
Answer
Modal dispersion
27
Question
What is the typical application domain for MMF?
Answer
Short-distance data transmission
28
Question
What is the core diameter given for a specific MMF in the notes?
Answer
40 microns
29
Question
What is the cladding diameter given for that MMF?
Answer
70 microns
30
Question
How does refractive index vary in graded index fiber?
Answer
Decreases gradually from center to edges