1. 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
Explanation: If the misalignment loss is known, the coupling efficiency is defined by
η = 1-Lt
Where η = coupling efficiency
Lt = misalignment loss.
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
Explanation: The total insertion loss in a single mode fiber is given by
TT = TL + Ta
Where, TT = total insertion loss
TL = lateral offset loss
Ta = Angular misalignment loss.
3. The intrinsic loss through a multimode fiber joint is independent of direction of propagation.
a) True
b) False
Explanation: Intrinsic loss is defined as the summation of lateral offset loss and angular misalignment loss. In case of multimode fibers, the intrinsic loss is dependent on the refractive index gradient. The intrinsic loss through a single mode fiber joint is independent of direction of propagation.
4. A permanent joint formed between two different optical fibers in the field is known as a ____________
a) Fiber splice
b) Fiber connector
c) Fiber attenuator
d) Fiber dispersion
Explanation: The jointing of two individual fibers is called as fiber splicing. It is used to establish long-haul optical fiber links by joining two small length fibers.
5. How many types of fiber splices are available?
a) One
b) Two
c) Three
d) Four
Explanation: Splices are divided into two types depending upon the splicing technique used. These are fusion splicing (welding) and mechanical splicing.
6. The insertion losses of the fiber splices are much less than the Fresnel reflection loss at a butted fiber joint.
a) True
b) False
Explanation: The Fresnel reflection loss is usually more because there is no large step change in refractive index with the fusion splice as it forms a continuous fiber connection. Also, some method of index matching tends to be utilized with mechanical splices.
7. What is the main requirement with the fibers that are intended for splicing?
a) Smooth and oval end faces
b) Smooth and square end faces
c) Rough edge faces
d) Large core diameter
Explanation: A curved mandrel is used which cleaves the fiber to achieve end preparation. The edges must be smooth and have square face at the end for splicing purpose.
8. In score and break process, which of the following is not used as a cutting tool?
a) Diamond
b) Sapphire
c) Tungsten carbide
d) Copper
Explanation: The score and break process is also called as scribe and break. It involves the scribing of the fiber surface under tension with a cutting tool. Copper is not used as a cutting tool.
9. The heating of the two prepared fiber ends to their fusing point with the application of required axial pressure between the two optical fibers is called as ____________
a) Mechanical splicing
b) Fusion splicing
c) Melting
d) Diffusion
Explanation: Fusion splicing is also called as welding. It refers to the welding of two fiber ends. It is essential for fusion splicing that the fiber ends are adequately positioned and aligned in order to achieve good continuity of the transmission medium at the junction point.
10. Which of the following is not used as a flame heating source in fusion splicing?
a) Microprocessor torches
b) Ox hydric burners
c) Electric arc
d) Gas burner
Explanation: Micro-plasma torches uses argon and hydrogen and alcohol vapor. The most widely used heating source is an electric arc. Thus, gas burner is not used in fusion splicing.