The document discusses various topics related to lasers including pumping processes, laser safety rules, optical pumping, transverse and longitudinal modes, and types of lasers. It explains that pumping involves transferring energy into the gain medium of a laser to produce population inversion allowing for stimulated emission. Optical pumping was developed in the 1950s by Alfred Kastler and involves using light to excite electrons. Common pump sources include laser diodes and flash lamps. Lasers have transverse and longitudinal modes that determine the emission spectrum. Different types of lasers discussed include gas dynamic lasers, chemical lasers, and TEM microscopes.

1. MUHAMMAD UMAIR

2. PUMPING
PROCESSES

3. LASER SAFETY RULES
1) Wear special goggles.
2) Never looking the primary laser beam or into the
specular
reflection of a beam.
3) Higher power beams should be terminated.
4) Skin protection should be worn at higher power
levels
( e.q. heavy white cloth )

4.  The technique was developed by 1966 Nobel
Prize winner Alfred Kastler in the early 1950s.
 Alfred Kastler. The Nobel Prize in
Physics 1966 was awarded to Alfred Kastler
for the discovery and development of optical
methods for studying Hertzian resonances in
atoms.

5. For his article that was published
Read more
at: https://http://citeseerx.ist.psu.edu/
viewdoc/download?doi=10.1.1.731.123
&rep=rep1&type=pdf

6.  Pumping is a process done by a device that raises, transfers, delivers, or
compresses fluids or that attenuates gases especially by suction or
pressure or both.
 Laser pumping is the act of energy transfer from an external source into
the gain medium of a laser. The energy is absorbed in the medium,
producing excited states in its atoms. When the number of particles in one
excited state exceeds the number of particles in the ground state or a less-
excited state, population inversion is achieved. In this condition, the
mechanism of stimulated emission can take place and the medium can act
as a laser or an optical amplifier.
 Light is amplified when the population inversion is positive.
 The pump energy is usually provided in the form of light or electric
current.

7.  Optical pumping is a process in which light energy is used to excite
electrons from a lower to higher energy level. It was first developed by
Alfred Kastler in the early 1950s.
 Optical pumping often takes place in laser action which involves
absorption of photons of light to raise the energy levels of electrons. These
electrons remain at higher energy state until they are activated to release
their stored energy in the form of a laser beam.
 Several types of lasers can be optically pumped. The most common
optically pumped lasers are doped-insulator solid-state lasers.

8.  Some of the common optical pump sources include:
 Laser diodes
 Discharge lamps
 Other types of laser sources such as dye lasers pumped with gas lasers and
titanium-sapphire lasers pumped with solid-state lasers

9.  Laser Flash Lamps or Gas discharge laser lamps are used as optical pump
sources for solid state lasers. The two main categories of laser pump
lamps are
 DC arc lamps for continuous pumping
 Laser flash lamps for pulsed pumping

10.  The pump power for which the Laser threshold is reached.
 The threshold pump power of an optically pumped laser is the value of the
pump power for which the laser threshold is just reached.
 At this point, the small-signal Gain equals the losses of the laser.
 . A similar threshold exists for some other types of Light sources, such as
e.g. Raman Lasers.
 Raman Lasers is now the days are used in instrument of solid state
technique named as RAMAN SPECTROSCOPY , every Physicst is
familiar with this Technique.

12.  In this method of pumping, electric discharge acts as the pump source or
energy source.
 A high voltage electric discharge (flow of electrons, electric charge, or
electric current) is passed through the laser medium or gas.

13. What is longitudinal
wave and transverse
wave?

14.  The operating modes of a physical system are formed by physical laws and
boundary conditions.
 . The superimposed waveforms that form the mode move with a fixed
velocity that is dependant on the properties of the system, and have
wavelengths equal to 2L/n, where L is the length of the string, and n is a
positive integer. These are the modes of the system.
 The longitudinal configuration or modes determines the emission
spectrum of the laser .
 The light bouncing repeatedly off the end mirrors set up standing waves
inside the cavity.

16.  A transverse mode of a beam of electromagnetic radiation is a particular
electromagnetic field pattern of radiation measured in a plane
perpendicular to the propagation direction of the beam. Transverse modes
occur in radio waves and microwaves confined to a waveguide, and also in
light waves in an optical fiber.
 Types of modes
Unguided electromagnetic waves in free space, can be described as a
superposition of plane waves; these can be described as TEM modes as defined
below.
 Transverse electromagnetic (TEM) modes: neither electric nor magnetic field in
the direction of propagation.
 Hybrid modes: non-zero electric and magnetic fields in the direction of
propagation.

18.  By a well known technique TEM.
 TEM-Transmission electron
microscope, that is used to view thin
specimens (molecules, etc) through
which electrons can pass and
generating a projection image.

21.  Gas dynamic lasers are constructed using the supersonic flow of gases, such
as carbon dioxide, to excite the molecules.
 A gas dynamic laser (GDL) is a laser based on differences in relaxation
velocities of molecular vibrational states.

22.  Chemical pumps are used to transfer chemicals and are designed to be
resistant to industrial liquids such as fuel, paint, bleach, solvents, etc.
 Chemical pumps can be either centrifugal pump or a positive
displacement pump depending on the specific application.
 How do chemical lasers work and its uses?
 A chemical laser is a laser that obtains its energy from
a chemical reaction. They are used in industry for cutting and drilling
common. examples of chemical lasers are the chemical oxygen
iodine laser coil.

24. Q:- What is Optical resonators? Also distinguish its types.
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