Light Ampliation by stimulated Emission of Laser

Lasers- Engineering Physics. A complete decription

1. “Fools find excuses
to cover their
inabilities”

2. LASER
(Light Amplification by Stimulated
Emission of Radiation)

3. What Is Laser
Properties Of Laser
Basic Concept Of Laser
Absorption
Spontaneous Emission
Stimulated Emission
The operation of the Laser
How a Laser Works
Population Inversion
Types of Laser
Applications of laser
Overview

4. What is Laser?
LightAmplificationbyStimulatedEmissionof
Radiation
•Adeviceproducesacoherentbeamofopticalradiation
bystimulatingelectronic,ionic,ormoleculartransitions
tohigherenergylevels
•MainlyusedinSingleModeSystems
•LightEmissionrange:5to10degrees
•RequireHighercomplexdrivercircuitrythanLEDs
•Laseractionoccursfromthreemainprocesses:photon
absorption,spontaneousemission,andstimulated
emission.

5. Properties of Laser
•Monochromatic
Concentrate in a narrow range of wavelengths
(one specific colour).
•Coherent
All the emitted photons bear a constant phase
relationship with each other in both time and
phase
•Directional
A very tight beam which is very strong and
concentrated.

6. Basic concepts for a laser
•Absorption
•Spontaneous Emission
•Stimulated Emission
•Population inversion

7. Absorption
•Energy is absorbed by an atom, the electrons
are excitedinto vacant energy shells.

8. Spontaneous Emission
•The atom decays from level 2 to level 1 through
the emission of a photon with the energy hv. It is
a completely randomprocess.

9. Stimulated Emission
•Atoms in an upper energy level can be triggered
or stimulated in phase by an incoming photonof
a specific energy.

10. Stimulated Emission
The stimulated photonshave unique properties:
–In phasewith the incident photon
–Same wavelengthas the incident photon
–Travel in same directionas incident photon

11. The operation of the Laser
Light: Coherent, polarized
The stimulating and emitted
photons have the same:
frequency
phase
direction

12. How a Laser Works

13. Condition for the laser operation
Ifn
1> n
2
•radiation is mostly absorbed absorbowane
•spontaneous radiation dominates.
•most atoms occupy level E2, weak absorption
•stimulatedemission prevails
•light is amplified
if n
2>> n
1-population inversion
Necessary condition:
population inversion
E
1
E
2

14. Population Inversion
•A state in which a substance has been
energized, or excited to specific energy levels.
•More atoms or molecules are in a higher excited
state.
•The process of producing a population inversion
is called pumping.
•Examples:
→by lamps of appropriate intensity
→by electrical discharge

15. Types of Laser

23. Applications of laser
1.Scientific
•Spectroscopy
•Lunar laser ranging
•Photochemistry
•Laser cooling
•Nuclear fusion
2. Military
•Death ray
•Defensive applications
•Strategic defense initiative
•Laser sight
•Illuminator
•Rangefinder
•Target designator

24. 3. Medical
Eye surgery
Cosmetic surgery
Application
4. Industry & Commercial
a. Cutting, welding, marking
b. CD player, DVD player
c. Laser printers, laser pointers
d. Photolithography
e. Laser light display

25. THANK YOU