Narrow – Linewidth and Wavelength – Tunable Lasers

Optical Communications

This set of Optical Communications Quiz focuses on “Narrow – Linewidth and Wavelength – Tunable Lasers”.

1. Which of these factors are critical in affecting the system performance in the case of coherent optical fiber transmission?
a) Laser line-width and stability
b) Refractive index and index difference
c) Core cladding diameter
d) Frequency

2. _______________ occurs as a result of the change in lasing frequency with gain.
a) Frequency multiplication
b) Dispersion
c) Attenuation
d) Line-width broadening

3. Laser cavity length can be extended by ___________
a) Increasing the refractive index
b) Reducing frequency
c) Introduction of external feedback
d) Using GRIN-rod lenses

4. What is the purpose of wavelength dispersive element is LEC lasers?
a) Wavelength selectivity
b) Reduction of line-width
c) Frequency multiplication
d) Avalanche multiplication

5. An effective method to reduce the line-width is to make the cavity longer.
a) True
b) False

6. Which devices are used to modulate the external cavity in order to achieve the higher switching speeds?
a) Electromagnetic
b) Acousto-optic
c) Dispersive
d) Lead

7. How many techniques are used to tune monolithic integrated devices (lasers)?
a) Five
b) One
c) Two
d) Three

8. _________________ laser can be produced when a coupler section is introduced between the amplifier and phase sections of a structure.
a) SG-DBR
b) GCSR
c) Y 4-shifted
d) DSM

9. The rare-earth-doped fiber lasers have spectral line-width in the range of _________________
a) 0.1 to 1 nm
b) 1.2 to 1.5 nm
c) 6 to 10 nm
d) 2 to 2.3 nm

10. The lasing line-width of Fox-smith resonator is ____________________
a) Less than 1 MHz
b) 1 MHz
c) 2 MHz
d) Greater than 3 MHz

11. What is the widest tuning range obtained in optical fiber laser structure?
a) 60 nm
b) 80 nm
c) More than 100 nm
d) 100 nm

12. How many techniques can be used to increase the injection cavity length?
a) One
b) Two
c) Three
d) Four

13. The mechanism which results from a refractive index change in the passive waveguide layer is called as ___________
a) Absorption
b) Spontaneous emission
c) Monolithic inversion
d) Bragg wavelength control

14. How many sections are included in a sampling grating distributed Bragg-reflector laser (SG-DBR)?
a) Four
b) Five
c) Three
d) Two

15. Fiber based lasers provide diffraction-limited power at higher levels than solid-state laser.
a) True
b) False

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