Lasers produce highly directional light through stimulated emission of radiation. They are characterized by coherence, directionality, monochromacity, and high intensity. Lasers use population inversion to produce stimulated emission, requiring more atoms or molecules to be in an excited state than a ground state. The first laser was created by Theodore Maiman in 1960 using a ruby crystal pumped by a flashlamp. Lasers now have many applications including barcodes scanners, laser pointers, laser eye surgery, fiber optic communications, and potentially future laser weapons. Safety precautions are required when working with lasers depending on their power classification.

1. LASERS
Abdul Hannan Mirza
(L1F20BSPH0016)
Muqaddas Tahir
(L1F20BSPH0033)
Muhammad Uzair
(L1F20BSPH0018)
Muhammad Ahmad
(L1F20BSPH0040)

2. L ight
A mplification
S timulated
E mission
R adiation

3. LASER:
 A laser is a device which produces highly directional
light
 It emits light through a process called stimulated
emission of radiation which increases the intensity of
light.
 A laser is different from conventional light sources in
four ways: coherence, directionality, monochromacity,
and high intensity.

4. CHARACTERISTICS OF LASERS
You can find a number of characteristics of laser light over ordinary
light source:
• Coherence
• Directionality
• Monochromatic
• High intensity

5. 1.Coherence
Visible light receives its emission from
electrons (electrons of the higher energy
level) are moved down to the lower energy
leve
2. Directionality
In conventional light sources like lamps,
torchlights, electric bulbs, etc, photons move
at random points. As such, these sources
scatter light in all possible directions. The
lasers emit light in a particular focused
direction
3. High Intensity
Wave intensity is the energy flowing through
a unit normal area per unit time. Light
an ordinary source spreads out in all
directions. The light of a laser is focused in a
particular direction.
4.Monochromatic
Monochromatic light means a light beam
which contains a single wavelength. Photons
that originate from natural light sources
contain a range of energies, wavelengths,
and colors
The Properties of Laser Similar to That of
Monochromatic Light Are
Frequency
Wavelength
Color

6. Laser Types and Uses
There are many types of lasers, and they are categorized based on the type of medium at
which they are used. This can be solid, liquid, gas, or semiconductor.
• Solid-State Lasers
• Gas Lasers
• Liquid Dye Lasers
• Semiconductor Lasers

7. Solid-State Lasers
• These lasers are made up of solid media, like ruby
or crystalline. The lasers have a flash tube
around it to excite the electrons.
• These types of lasers are typically used for target
destination systems by military applications and
also to drill holes in metals
Gas Lasers
• These types of lasers are made out of helium or
helium-neon. They are used to produce
characteristic red laser light.
• These lasers are powerful and efficient and are
used for industrial cutting and welding
applications.
Liquid Dye Lasers
• Tdiode lasers, as they use LEDs to generate light in
a monochromatic pattern.
• he liquid dye lasers use liquid dyes like rhodamine
in a liquid solution as their medium. In these
lasers, the electrons are excited either by an arc
lamp, flash lamp, or another laser.
• Liquid dye lasers can produce a broader band of
light frequencies as compared to solid-state or
liquid lasers and are used in a variety of
applications.
Semiconductor Lasers
• These types of lasers are very cheap to produce
and hence found in several electronic devices like
laser printers and barcode scanners.
• These are also called

9. Laser Type Wavelength
Argon fluoride (UV) 193
Krypton fluoride (UV) 248
Xenon fluoride (UV) 308
Nitrogen (UV) 337
Argon (blue) 488
Argon (green) 514
Helium neon (green) 543
Wavelength of types of lasers

10. PRODUCTION OF
LASER
Muhammad Uzair (L1F20BSPH0018)

11. • Absorption:
When an atom absorb energy, the
electrons are exited in high energy levels
• Spontaneous emission:
As the high level are highly unstable, the
atom decays from level 2 to level
1instantly with the emission of a photon
with the energy hv, which is random in
nature
• Stimulated emission:
When the higher level is metastable, an
incoming photon of resonant energy can
stimulate it to move to ground state with the
emission of another photon which is coherent
with the incident photon
The stimulated emission produces a copy of
incident photon as it is:
• In phase with the incident photon
• Of same wavelength as the incident photon
• Travel in same direction as incident photon
Some Perquisitions

12. Population Inversion
⚫ More atoms or molecules are in a higher excited state than in ground state.
⚫ The process of producing a population inversion is called pumping.
⚫ Examples: →by direct collisions →by electrical discharge

14. CONDITION FOR LASERS OPERATION
 If n 1>n2
radiation is mostly absorbed
 spontaneous radiation dominates.
 If n2 >> n1 - population inversion
stimulated emission prevails
 light is amplified

15. • How to realized the population inversion ?
• Thermal excitation
𝑛2
𝑛1
= exp(
−Δ𝐸
𝐾𝑇
)
It is impossible
The system has to be “pumped”

16. History of LASERS
Muqadass Tahir (L1F20BSPH0033)

17. Einstein( the starter)
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 Planck's law of radiation, conceptually based upon
probability coefficients (Einstein coefficients) for the absorption, spontaneous emission,
and stimulated emission of electromagnetic radiation.

18. Short Stop (What is Maser)
• A maser (an acronym for microwave amplification by
stimulated emission of radiation) is a device that
produces coherent electromagnetic waves through amplification
by stimulated emission. The first maser was built by Charles H.
Townes, James P. Gordon, and Herbert J. Zeiger at Columbia
University in 1953

19. First Laser
• At Columbia University, graduate student Gordon Gould was
working on a doctoral thesis about the energy levels of
excited thallium. When Gould and Townes met, they spoke of
radiation emission, as a general subject; afterwards, in November
1957, Gould noted his ideas for a "laser", including using an
open resonator (later an essential laser-device component).

20. L A S E R
• LASER notebook: First page of the notebook wherein Gordon
Gould coined the acronym LASER, and described the elements
required to construct one.

21. First practical LASER
• On May 16, 1960, Theodore H. Maiman operated the first functioning
laser at Hughes Research Laboratories, Malibu, California, ahead of
several research teams, including those of Townes, at Columbia
University, Arthur Schawlow, at Bell Labs, and Gould, at the TRG
(Technical Research Group) company.
The First LASER
Maiman's functional laser used a flashlamp-pumped
synthetic ruby crystal to produce red laser light at 694 nanometers
wavelength.

22. Applications
of LASER
Muhammad Ahmad (L1F20BSPH0040)

23. History

24. “A solution looking for a problem"
Barcode scanner
o First use1960
 Introduced in 1974 consumer electronics,
 Information technology, science, industry
 Law enforcement
 Fiber-optic communication

25. • Laserdisc player, introduced in 1978
•1982 followed shortly by laser printers.

26. Spoiler (The record breaker)
• One of the most sacred laws of physics is that nothing can travel
faster than the speed of light in vacuum. But this speed limit has been
smashed in a recent experiment in which a laser pulse travels at
more than 300 times the speed of light (L J Wang et al.)

27. Present-day Application of LASER
• In medicine
• Industry
• Research
• Communication in Space

28. Future use (Hint it's Bright)
LASER weapon

29. LASER Weapon
• A laser weapon is
a directed-energy
weapon based on lasers
•Dazzler

30. Safety Precautions
Theodore Maiman
" The Gillette "
Class 1
Class 2
Class 3R
Class 3B
Class 4 lasers