The document discusses lasers, detailing their history, characteristics, principles, and applications. It explains how lasers produce coherent light through stimulated emission and outlines various components such as the active medium, pumping methods, and optical resonators. Applications of lasers range from information processing and industrial uses to medical applications and high-energy research.

1. SARVAJANIK COLLEGE OF
ENGINEERING AND
TECHNOLOGY
Physics
(2110011)
Computer Engineering – II
B.E. – I year
Topic:
Laser and its application

2. Group members
Name Roll no.
barodiya priyank 56
Vadodariya keyur 57
Jain Rishika 58
Thakur pathik 59
Patel palak 60
Patel Ishani 61
Patel Himani 62
Shah priyansh 63
Shah abhinandan 64
Khandwala mudra 65
Parmar siddhant 66
Patel harsh 67

3. Annexure
 History of Laser
 Characteristics of Laser
 Basic Principles of Laser
 ND-YAG LASER
 Applications of Laser

4. What is Laser?
Light Amplification by Stimulated
Emission of Radiation
 A device produces a coherent beam of optical rad
iation by stimulating electronic, ionic, or molecul
ar transitions to higher energy levels
 When they return to lower energy levels by stimu
lated emission, they emit energy.

5. History of Laser
 In 1917, Albert Einstein established the
theoretical foundations for the laser and
the maser in the paper Zur Quantentheorie der
Strahlung (On the Quantum Theory of
Radiation) via a re-derivation of Max Plank’s
law of radiation, conceptually based upon
probability coefficients (Einstein’s coefficient)
for the absorption, spontaneous emission, and
stimulated emission of electromagnetic
radiation.

6.  In 1928, Rudolf W. Ladenburg confirmed
the existence of the phenomenon of
stimulated emission and negative
absorption. In 1939, Valentin A. Fabrikant
predicted the use of stimulated emission
to amplify "short" waves.

7. Characteristics of Laser
Highly Monochromatic
Highly Coherent
Highly Directional
Highly Intense (brightness)

8.  The light emitted from a laser is monochromatic,
that is, it is of one color/wavelength. In contrast,
ordinary white light is a combination of many col
ors (or wavelengths) of light.
 Lasers emit light that is highly directional, that is,
laser light is emitted as a relatively narrow beam i
n a specific direction. Ordinary light, such as fro
m a light bulb, is emitted in many directions awa
y from the source

9.  The light from a laser is said to be coherent, which
means that the wavelengths of the laser light are in
phase in space and time. Ordinary light can be a
mixture of many wavelengths.
 The intensity of a light source is the power emitted
per unit surface area per unit solid angle. Laser is
highly intense beam

11. Basic Principles of Laser
 Spontaneous emission
 Stimulated emission
 Amplification
 Population inversion
 Active medium
 Pumping
 Optical resonators

12. hn
absorption
emission Stimulated emission

13. iE
fE
MirrorMirror
Stimulated emission

14. Amplification
 Amplification is the act or means of
increase of the physical quantity.
 We can see that in stimulated
emission , there is an increase in
numbers of photons.
 For amplification of light we need
stimulated emission only

15. Population inversion
 Population of atoms or electrons in any
energy level is given by
In practice the population inversion is possible
when there is an existence of meta stable
state of energy.











 KT
E
eNN 0

16. Normal Population
E1
E2
E3
No of electrons

17. Population Inversion
E1
E2
E3
Metastable state
Number of electrons

18. Active Medium
 The Active medium is the solid , gas
or any solid state medium which has
meta stable state and able to create
population inversion and can amplify
the light.

19. Pumping
 The processes in which the external energy is
consume to make an electron or atom to
undergo transition from low energy state to
higher one is known as pumping.

20. Types of pumping
Direct Pumping
{ Primary Pumping}
Optical electrical
Direct
conversion chemical
Indirect Pumping
{ Secondary Pumping}

21. OPTICAL PUMPING
 If the luminous energy [light] is supplied to a
medium for causing population inversion , then
pumping is known as OPTICAL PUMPING

22. Electrical Pumping
 The pumping by electric discharge is
preferred in the laser materials whose
higher energy levels have narrow
band width e.g. Argon ion laser.

23. Direct conversion
 A direct conversion of electrical energy
to radiant energy. e.g. LED and semi
conductor laser.

24. Chemical
 In the chemical pumping energy from
a chemical reaction is use for the
excitation of atoms.

25. Indirect Pumping
 The later atom provide the population
inversion needed for laser emission.
X Y

26. Optical Resonator
 An optical resonator is needed to build up the light
energy in the beam. The resonator is formed by placing a
pair of mirrors facing each other so that light emitted
along the line between the mirrors is reflected back and
forth. When a population inversion is created in the
medium, light reflected back and forth increases in
intensity with each pass through the laser medium.
 If the laser generates a continuous beam, the amount of
light added by stimulated emission on each round trip
between the mirrors equals the light emerging in the
beam plus losses within the optical resonator

27. Working of laser

28. iE
fE
Mirror Mirror
Population inversion

29. iE
fE
Mirror Mirror
Spontaneous emission

30. iE
fE
MirrorMirror
Stimulated emission

31. iE
fE
MirrorMirror
Feed-back by the cavity

32. iE
fE
MirrorMirror
Stimulated emission

33. iE
fE
MirrorMirror
Feed-back by the cavity

34. iE
fE
MirrorMirror
Laser beam
After several round trips…

35. Nd:YAG laser
Nd:YAG (neodymium-doped yttrium
aluminium garnet;)
Nd:Y3Al5O12
Nd: YAG laser is Four level laser
Nd:YAG lasers are optically pumped using
a Xenon / Krypton flash lamp

36. Nd: YAG Rod
M1
M2
Xenon Krypton
flash lamp

37. Applications of laser
 Transmission and processing of
information
 Laser scanners
 Optical discs
 Fibre-optic communication systems
 Alignment, measurement, and imaging
 Surveying

38. Industrial uses
 Laser energy can be
focused in space and
concentrated in time so
that it heats, burns away,
or vaporizes many
materials. Although the
total energy in a laser
beam may be small, the
concentrated power on
small spots or during short
intervals can be
enormous.

39. Medical applications
 Surgical removal of tissue with a laser is a
physical process similar to industrial laser
drilling. Carbon-dioxide lasers burn away
tissue because their infrared beams are
strongly absorbed by the water that makes
up the bulk of living cells. A laser beam
cauterizes the cuts, stopping bleeding in
blood-rich tissues such as the female
reproductive tract or the gums.

41. High-energy lasers
 Scientists have shown
that lasers can
concentrate extremely
high powers in either
pulses or continuous
beams. Major
applications for these
high-power levels
are fusion research,
nuclear weapons testing,
and missile defense.

42. THANK YOU