Some Injection Laser Structures

Optical Communications

This set of Optical Communications Multiple Choice Questions & Answers (MCQs) focuses on “Some Injection Laser Structures”.

1. In multimode injection lasers, the construction of current flow to the strip is obtained in structure by __________
a) Covering the strip with ceramic
b) Intrinsic doping
c) Implantation outside strip region with protons
d)Implantation outside strip region with electrons

2. What is the strip width of injection laser?
a) 12 μm
b) 11.5 μm
c) Less than 10 μm
d) 15 μm

3. Some refractive index variation is introduced into lateral structure of laser.
a) True
b) False

4. Buried hetero-junction (BH) device is a type of _____________ laser where the active volume is buried in a material of wider band-gap and lower refractive index.
a) Gas lasers.
b) Gain guided lasers.
c) Weak index guiding lasers.
d) Strong index guiding lasers.

5. In Buried hetero-junction (BH) lasers, the optical field is confined within __________
a) Transverse direction
b) Lateral direction
c) Outside the strip
d) Both transverse and lateral direction

6. A double-channel planar buried hetero-structure (DCP BH) has a planar active region, the confinement material is?
a) Alga AS
b) InGaAsP
c) GaAs
d) SiO2

7. Problems resulting from parasitic capacitances can be overcome __________
a) Through regrowth of semi-insulating material
b) By using oxide material
c) By using a planar InGaAsP active region
d) By using a AlGaAs active region

8. Quantum well lasers are also known as __________
a) BH lasers
b) DH lasers
c) Chemical lasers
d) Gain-guided lasers

9. Quantum well lasers are providing high inherent advantage over __________
a) Chemical lasers
b) Gas lasers
c) Conventional DH devices
d) BH device

10. Strip geometry of a device or laser is important.
a) True
b) False

11. Better confinement of optical mode is obtained in __________
a) Multi Quantum well lasers
b) Single Quantum well lasers
c) Gain guided lasers
d) BH lasers

12. Multi-quantum devices have superior characteristics over __________
a) BH lasers
b) DH lasers
c) Gain guided lasers
d) Single-quantum-well devices

13. Dot-in-well device is also known as __________
a) DH lasers
b) BH lasers
c) QD lasers
d) Gain guided lasers

14. A BH can have anything from a single electron to several electrons.
a) True
b) False

15. QD lasers have a very low threshold current densities of range __________
a) 0.5 to 5 A cm-2
b) 2 to 10 A cm-2
c) 10 to 30 A cm-2
d) 6 to 20 A cm-2

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