This set of Optical Communications Multiple Choice Questions & Answers (MCQs) focuses on “Fiber Alignment and Joint Loss”.

1. A measure of amount of optical fiber emitted from source that can be coupled into a fiber is termed as ______________

a) Radiance

b) Angular power distribution

c) Coupling efficiency

d) Power-launching

2. The ratio r = (n1 – n)/(n1 – n) indicates ____________

a) Fresnel reflection

b) Reflection coefficient

c) Refraction coefficient

d) Angular power distribution coefficient

3. A GaAs optical source having a refractive index of 3.2 is coupled to a silica fiber having a refractive index of 1.42. Determine Fresnel reflection at interface in terms of percentage.

a) 13.4%

b) 17.4%

c) 17.6%

d) 14.8%

4. A particular GaAs fiber has a Fresnel reflection magnitude of 17.6% i.e. 0.176. Find the power loss between the source and the fiber?

a) 0.86 dB

b) 0.78 dB

c) 0.84 dB

d) 0.83 dB

5. Two joined step index fibers are perfectly aligned. What is the coupling loss of numerical aperture are NA_{R}= 0.26 for emitting fiber?

a) -0.828 dB

b) -0.010 dB

c) -0.32 dB

d) 0.32 dB

6. Two joined graded index fibers that are perfectly aligned have refractive indices α_{R} = 1.93 for receiving fiber α_{E} = 2.15 for emitting fiber. Calculate the coupling loss.

a) 0.23 dB

b) 0.16 dB

c) 0.82 dB

d) 0.76 dB

7. How many types of misalignments occur when joining compatible fiber?

a) One

b) Two

c) Five

d) Three

8. Losses caused by factors such as core-cladding diameter, numerical aperture, relative refractive index differences, different refractive index profiles, fiber faults are known as ____________

a) Intrinsic joint losses

b) Extrinsic losses

c) Insertion losses

d) Coupling losses

9. A step index fiber has a coupling efficiency of 0.906 with uniform illumination of all propagation modes. Find the insertion loss due to lateral misalignment?

a) 0.95 dB

b) 0.40 dB

c) 0.42 dB

d) 0.62 dB

10. A graded index fiber has a parabolic refractive index profile (α=2) and core diameter of 42μm. Estimate an insertion loss due to a 2 μm lateral misalignment when there is index matching and assuming there is uniform illumination of all guided modes only.

a) 0.180

b) 0.106

c) 0.280

d) 0.080

11. Determine coupling efficiency if the misalignment loss in a graded index fiber is 0.102.

a) 0.136

b) 0.898

c) 0.982

d) 0.684

12. In a single mode fiber, the losses due to lateral offset and angular misalignment are given by 0.20 dB and 0.46 dB respectively. Find the total insertion loss.

a) 0.66 dB

b) 0.26 dB

c) 0.38 dB

d) 0.40 dB

13. The intrinsic loss through a multimode fiber joint is independent of direction of propagation.

a) True

b) False