N A L A N D A O P E N U N I V E R S I T Y
M.Sc. Physics, Part-II
PAPER-XIV
(Photonics)
Annual Examination, 2017
Time 3 Hours. Full Marks 80
Answer any Five Questions. All questions carry equal marks.
1. What do you mean by photonics How is it different from electronics Comment on the
future of this branch of physics.
2. Describe a light emitting diode (LED). What do you mean by injected holes and electrons
3. Describe the composition of a solar cell. How does the output current of solar cell depend on the
intensity of the incident radiation
4. Explain the following terms
Brewster Window, Quantum well diode laser,
Monolayer diode laser, and Fermi Level.
5. Describe an injection laser. What is double heterojunction injection laser Explain the term
injection.
6. Derive the condition of lasing in terms of the gain and loss coefficient per unit length and the
relativity to mirrors placed at the end faces of the laser crystal.
7. Obtain expressions for the following terms related to an optical fibre Critical angle,
Numerical aperture, acceptance angle, relative refractive index difference.
8. Starting from the Maxwell's field equations, derive the wave equations for E z and Hz
components for an e.m. wave travelling along positive z-direction.
9. Extend the concept of beats from the acoustical to optical region. How does the beat
formation help in deciding the changes in phase of the laser source
10. How optical computer is different from electronic computer Why the optical computer is
going to be faster than electronic computes in operation