This document discusses the basic concepts of laser physics. It explains that population inversion, which is required for laser action, can be achieved through a process called pumping. Pumping involves exciting atoms from a lower energy state to a higher energy state using an external energy source. Different types of lasers use various pumping techniques, such as optical pumping in solid state lasers, electrical pumping in semiconductor lasers, and direct energy conversion in gas lasers. The active medium achieving population inversion can be solid, liquid, gas or plasma. Common types of lasers include solid state, liquid, gaseous, dye, and semiconductor lasers. A laser consists of an active medium situated between two mirrors, one a perfect reflector and the

1. TITLE : BASIC CONCEPT OF
LASER PHYSICS

2. State of achieving more number
of atom in the excited state
compared to the ground state.
Population inversion can be
Achieved By a process called
pumping

3. Mechanism of exciting atoms
from the lower energy state to
a higher energy state by
supplying energy from an
external source.

4. Atom are excited by means of
an external optical source
This is adopted in solid state
lasers such as ruby laser and
Nd:yag laser.

5. The electrons are accelerated
to a high velocity by a strong
electric field.
This technique of pumping is
adopted in gas laser such as
co2 laser

6. In this type pumping, a direct
conversion of electric energy
into light takes place.
This technique of pumping is
adopted in semiconductor
laser.

7. Which leads to emission of
stimulated photons after
established the population
inversion is referred ta as
lasing.

8. The limited time for which a
particle or an atom remains
in the excited is know as life
time.
It is a about a nano second.

9. The energy levels in an
atomic system where life
time of atoms is very large.
This property helps in
achieving the population
inversion.

10. Population inversion is
achieved for laser action is
called active medium.
The medium can be solid,
liquid, gas and plasma.

11. (1) Solid state lasers
(2) Liquid lasers
(3) Gaseous lasers
(4) Dye lasers
(5) Semiconductor lasers

12. It is a pair of reflecting
surface of which one is a
perfect reflector and the
other is a partial reflector.