Answer: Laser

Advertisement

Advertisement

Questions

1
Which of the following can be used in a vibrational analysis of structure?

Answer: Laser

Advertisement

4
Which of the following can be used for generation of laser pulse?

Answer: Nd- YAG laser

5
Calculate the number of photons, from green light of mercury (ʎ = 4961 Å),required to do one joule of work.

Answer: 2.4961×1018/m3

6
Calculate the wavelength of radiation emitted by an LED made up of a semiconducting material with band gap energy 2.8eV.

Answer: 4430.8 Å

9
A device which converts electrical energy in the form of a current into optical energy is called as

Answer: Optical source

11
The frequency of the absorbed or emitted radiation is related to difference in energy E between the higher energy state E2 and the lower energy state E1. State what h stands for in the given equation?
E =E2 – E1 = hf

Answer: Planck’s constant

12
The radiation emission process (emission of a proton at frequency) can occur in __________ ways.

Answer: Two

13
Which process gives the laser its special properties as an optical source?

Answer: Stimulated emission

14
An incandescent lamp is operating at a temperature of 1000K at an operating frequency of 5.2×1014 Hz. Calculate the ratio of stimulated emission rate to spontaneous emission rate.

Answer: 1.47×10-11

15
The lower energy level contains more atoms than upper level under the conditions of ________________

Answer: Thermal equilibrium

16
__________________ in the laser occurs when photon colliding with an excited atom causes the stimulated emission of a second photon.

Answer: Light amplification

17
A ruby laser has a crystal of length 3 cm with a refractive index of 1.60, wavelength 0.43 μm. Determine the number of longitudinal modes.

Answer: 2.2×105

18
A semiconductor laser crystal of length 5 cm, refractive index 1.8 is used as an optical source. Determine the frequency separation of the modes.

Answer: 1.6 GHz

19
An injection laser has active cavity losses of 25 cm-1and the reflectivity of each laser facet is 30%. Determine the laser gain coefficient for the cavity it has a length of 500μm.

Answer: 49.07 cm-1

20
Considering the values given below, calculate the mode separation in terms of free space wavelength for a laser.Frequency separation = 2GHz Wavelength = 0.5 μm.

Answer: 1.6×10-12

Advertisement