Fiber Couplers

Optical Communications

This set of Optical Communications Multiple Choice Questions & Answers (MCQs) focuses on “Fiber Couplers”.

1. When considering source-to-fiber coupling efficiencies, the ________ is an important parameter than total output power.
a) Numerical aperture
b) Radiance of an optical source
c) Coupling efficiency
d) Angular power distribution

2. It is a device that distributes light from a main fiber into one or more branch fibers.
a) Optical fiber coupler
b) Optical fiber splice
c) Optical fiber connector
d) Optical isolator

3. Optical fiber couplers are also called as ________________
a) Isolators
b) Circulators
c) Directional couplers
d) Attenuators

4. How many types of multiport optical fiber couplers are available at present?
a) Two
b) One
c) Four
d) Three

5. The optical power coupled from one fiber to another is limited by ____________
a) Numerical apertures of fibers
b) Varying refractive index of fibers
c) Angular power distribution at source
d) Number of modes propagating in each fiber

6. ________ couplers combine the different wavelength optical signal onto the fiber or separate the different wavelength optical signal output from the fiber.
a) 3-port
b) 2*2-star
c) WDM
d) Directional

7. How many fabrication techniques are used for 3 port fiber couplers?
a) One
b) Two
c) Three
d) Four

8. Which is the most common method for manufacturing couplers?
a) Wavelength division multiplexing
b) Lateral offset method
c) Semitransparent mirror method
d) Fused bi-conical taper (FBT) technique

9. Couplers insertion loss is same as that of excess loss.
a) True
b) False

10. A four-port multimode fiber FBT coupler has 50 μW optical power launched into port 1. The measured output power at ports 2,3 and 4 are 0.003, 23.0 and 24.5 μW respectively. Determine the excess loss.
a) 0.22 dB
b) 0.33 dB
c) 0.45 dB
d) 0.12 dB

11. A four-port FBT coupler has 60μW optical power launched into port one. The output powers at ports 2, 3, 4 are 0.0025, 18, and 22 μW respectively. Find the split ratio?
a) 42%
b) 46%
c) 52%
d) 45%

12. How many manufacturing methods are used for producing multimode fiber star couplers?
a) Two
b) One
c) Three
d) Five

13. Calculate the splitting loss if a 30×30 port multimode fiber star coupler has 1 mW of optical power launched into an input port.
a) 13 dB
b) 15 dB
c) 14.77 dB
d) 16.02 dB

14. A _____________ coupler comprises a number of cascaded stages, each incorporating three or four-port FBT couplers to obtain a multiport output.
a) Star
b) Ladder
c) WDM
d) Three-port

15. A number of three-port single-mode fiber couplers are used in the fabrication of a ladder coupler with 16 output ports. The three-port couplers each have an excess loss of 0.2 dB along with a splice loss of 0.1 dB at the interconnection of each stage. Determine the excess loss.
a) 1.9 dB
b) 1.4 dB
c) 0.9 dB
d) 1.1 dB

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