Explore topic-wise MCQs in Optical Communication.

This section includes 25 Mcqs, each offering curated multiple-choice questions to sharpen your Optical Communication knowledge and support exam preparation. Choose a topic below to get started.

1.

Digital transmission is more likely to be affected by modal noise.

A. True
B. False
Answer» C.
Discussion
2.

The modal noise can be reduced by __________

A. Decreasing width of signal longitudinal mode
B. Increasing coherence time
C. Decreasing number of longitudinal modes
D. Using fiber with large numerical aperture
Answer» E.
Discussion
3.

Disturbance along the fiber such as vibrations, discontinuities, connectors, splices, source/detectors coupling result in __________

A. Modal noise
B. Inter-symbol interference
C. Infrared interference
D. Pulse broadening
Answer» B. Inter-symbol interference
Discussion
4.

The modal noise occurs when uncorrected source frequency is?

A. δf>>1/δT
B. δf=1/δT
C. δf<<1/δT
D. Negligible
Answer» B. δf=1/δT
Discussion
5.

Practical pulse broadening value for graded index fiber lies in the range of __________

A. 0.9 to 1.2 ns/km
B. 0.2 to 1 ns/km
C. 0.23 to 5 ns/km
D. 0.45 to 8 ns/km
Answer» C. 0.23 to 5 ns/km
Discussion
6.

Intermodal dispersion in multimode fibers is minimized with the use of step-index fibers.

A. True
B. False
Answer» C.
Discussion
7.

The index profile of a core of multimode graded index fiber is given by?a) N (r) = n1 [1 – 2Δ(r2/a)2]1/2; r

A. N (r) = n1 [1 – 2Δ(r2/a)2]1/2; r<a
B. N (r) = n1 [3 – 2Δ(r2/a)2]1/2; r<a
C. N (r) = n1 [5 – 2Δ(r2/a)2]1/2; r>a
D. N (r) = n1 [1 – 2Δ(r2/a)2]1/2; r<a
Answer» E.
Discussion
8.

The differential attenuation of modes reduces intermodal pulse broadening on a multimode optical link.

A. True
B. False
Answer» B. False
Discussion
9.

Consider a single mode fiber having core refractive index n1= 1.5. The fiber length is 12m. Find the time taken by the axial ray to travel along the fiber.

A. 1.00μsec
B. 0.06μsec
C. 0.90μsec
D. 0.30μsec
Answer» C. 0.90μsec
Discussion
10.

After Total Internal Reflection the Meridional ray __________

A. Makes an angle equal to acceptance angle with the axial ray
B. Makes an angle equal to critical angle with the axial ray
C. Travels parallel equal to critical angle with the axial ray
D. Makes an angle equal to critical angle with the axial ray
Answer» E.
Discussion
11.

Intermodal dispersion occurring in a large amount in multimode step index fiber results in ____________

A. Propagation of the fiber
B. Propagating through the fiber
C. Pulse broadening at output
D. Attenuation of waves
Answer» D. Attenuation of waves
Discussion
12.

PRACTICAL_PULSE_BROADENING_VALUE_FOR_GRADED_INDEX_FIBER_LIES_IN_THE_RANGE_OF?$

A. 0.9 to 1.2 ns/km
B. 0.2 to 1 ns/km
C. 0.23 to 5 ns/km
D. 0.45 to 8 ns/km
Answer» C. 0.23 to 5 ns/km
Discussion
13.

Disturbance along the fiber such as vibrations, discontinuities, connectors, splices, source/detectors coupling result in$

A. Modal noise
B. Inter-symbol interference
C. Infrared interference
D. Pulse broadening
Answer» E.
Discussion
14.

The modal noise occurs when uncorrected source frequency is$

A. δf>>1/δT
B. δf=1/δT
C. δf<<1/δT
D. Negligible
Answer» B. ‚âà√≠¬¨‚Ä¢f=1/‚âà√≠¬¨‚Ä¢T
Discussion
15.

Digital transmission is more likely to be affected by modal noise. State true or false

A. True
B. False
Answer» C.
Discussion
16.

The modal noise can be reduced by

A. Decreasing width of signal longitudinal mode
B. Increasing coherence time
C. Decreasing number of longitudinal modes
D. Using fiber with large numerical aperture
Answer» E.
Discussion
17.

Estimate RMS pulse broadening per km due to intermodal dispersion for multimode step index fiber where length of fiber is 4 km and pulse broadening per km is 80.6 ns?

A. 18.23ns/km
B. 20.15ns/km
C. 26.93ns/km
D. 10.23ns/km
Answer» C. 26.93ns/km
Discussion
18.

Intermodal dispersion in multimode fibers is minimized with the use of step-index fibers. State whether the given statement is true or false.

A. True
B. False
Answer» C.
Discussion
19.

The index profile of a core of multimode graded index fiber is given by-

A. N (r) = n1 [1 – 2Δ(r<sup>2</sup>/a)<sup>2</sup>]<sup>1/2</sup>; r<a
B. N (r) = n1 [3 – 2Δ(r<sup>2</sup>/a)<sup>2</sup>]<sup>1/2</sup>; r<a
C. N (r) = n1 [5 – 2Δ(r<sup>2</sup>/a)<sup>2</sup>]<sup>1/2</sup>; r>a
D. N (r) = n1 [1 – 2Δ(r<sup>2</sup>/a)<sup>2</sup>]<sup>1/2</sup>; r<a
Answer» E.
Discussion
20.

The differential attenuation of modes reduces intermodal pulse broadening on a multimode optical link. State whether the given statement is true or false.

A. True
B. False
Answer» B. False
Discussion
21.

A multimode step-index fiber has a core refractive index of 1.5 and relative refractive index difference of 1%. The length of the optical link is 6 km. Estimate the RMS pulse broadening due to intermodal dispersion on the link.

A. 92.6 ns
B. 86.7 ns
C. 69.3 ns
D. 68.32 ns
Answer» C. 69.3 ns
Discussion
22.

A 4 km optical link consists of multimode step index fiber with core refractive index of 1.3 and a relative refractive index difference of 1%. Find the delay difference between the slowest and fastest modes at the fiber output.

A. 0.173 μsec
B. 0.152 μsec
C. 0.96 μsec
D. 0.121 μsec
Answer» B. 0.152 ‚âà√≠¬¨‚à´sec
Discussion
23.

Consider a single mode fiber having core refractive index n1= 1.5.

A.
B. 1.00μsec
C. 0.06μsec
Answer» C. 0.06‚âà√≠¬¨‚à´sec
Discussion
24.

After Total Internal Reflection the Meridional ray

A. Makes an angle equal to acceptance angle with the axial ray
B. Makes an angle equal to critical angle with the axial ray
C. Travels parallel equal to critical angle with the axial ray
D. Makes an angle equal to critical angle with the axial ray
Answer» E.
Discussion
25.

Intermodal dispersion occurring in a large amount in multimode step index fiber results in

A. Propagation of the fiber
B. Propagating through the fiber
C. Pulse broadening at output
D. Attenuation of waves
Answer» D. Attenuation of waves
Discussion