Mid – Infrared and Far – Infrared Lasers

Optical Communications

This set of Optical Communications Multiple Choice Questions & Answers (MCQs) focuses on “Mid Infrared and Far Infrared Lasers”.

1. The parameters having a major role in determining threshold current of efficiency of injection laser are ___________
a) Angle recombination and optical losses
b) Frequency chirping
c) Relaxation oscillation
d) Mode hopping

2. Auger current is mostly ___________________ for material with band gap providing longer wavelength emission.
a) Unaffected
b) Lesser
c) Larger
d) Vanishes

3. Injection lasers operating in smaller wavelengths are subjected to increased carrier losses.
a) True
b) False

4. Devices based on quaternary PbSnSeTe and their ternary compounds, emit at wavelength?
a) Between 3-4 μm
b) Longer than 4 μm
c) Between 3.5 to 4.2 μm
d) Between 2 to 3 μm

5. Replacing Sn with Eu, Cd or Ge in some _________________ the band gap.
a) Remove the band gap
b) Does not affect
c) Decreases
d) Increases

6. Lasing obtained in __________ when 191 mW of pump light at a wavelength of 0.477 μm is launched into laser.
a) Ternary PbSnSeTe alloy laser
b) Quaternary PbSnSeTe alloy laser
c) Doped Fluoro-zirconate fiber
d) Ternary PbEuTe alloy laser

7. The thulium doped fiber laser when pumped with alexandrite laser output at 0.786 μm, the laser emits at ___________
a) 0.6 μm
b) 0.8 μm
c) 2.3 μm
d) 1.2μm

8. The diode-cladding-pumped Erbium praseodymium-doped fluoride device operates at wavelength.
a) Around 3 μm
b) 4 μm
c) 2.6 μm
d) 1.04 μm

9. A technique based on inter-sub band transition is known as ___________
a) Auger recombination
b) Frequency chirping
c) Inter-valence band absorption
d) Quantum cascading

10. In a QC laser, a same electron can emit number of photons.
a) True
b) False

11. The phenomenon resulting in the electrons to jump from one state to another each time emitting of photon is known as ___________
a) Inter-valence band absorption
b) Mode hopping
c) Quantum cascading
d) Quantum confinement

12. A QC laser is sometimes referred as ___________
a) Unipolar laser
b) Bipolar laser
c) Gain guided laser
d) Non semiconductor laser

13. In QC lasers, it is possible to obtain different output signal wavelengths. This can be achieved by ___________
a) Inter-valence band absorption
b) Mode hopping
c) Quantum cascading
d) Selecting layers of different thickness

14. QC lasers ______________ the performance characteristics.
a) Have negligible effects
b) Does not affects
c) Improves
d) Degrades

15. An MQW cascaded laser is more advantageous because of ___________
a) Mode hopping
b) Auger recombination
c) Control over layers of material
d) Properties of material

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