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

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

a) Fresnel reflection

b) Reflection coefficient

c) Refraction coefficient

d) Angular power distribution coefficient

2. 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

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 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

5. 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

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. 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

8. 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

9. 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

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

a) One

b) Two

c) Five

d) Three

11. 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

12. 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

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

a) True

b) False