Introduction to Laser

Things you need to know
Before studying about lasers, you must be familiar with basic
terms used to describe electromagnetic waves:
Wavelength (?)
Frequency (?)
Period (T)
Velocity of light (c)
Index of refraction (n)
We will briefly review these terms, but it is much better if you
are familiar with:
Some terms from geometric optics such as: refraction, reflection,
thin lenses etc.
Some terms from "Modern Physics" such as photons, Models of
atoms, etc.
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
28/10/1431
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Electromagnetic Radiation
Electromagnetic Radiation is a transverse wave,
advancing in vacuum at a constant speed which is
called: velocity of light.
All electromagnetic waves have the same velocity in
vacuum, and its value is approximately:
c = 300,000 [km/sec] = 3*108 [m/sec]
One of the most important parameters of a wave is its
wavelength.
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
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Wavelength
Wavelength (?) (Lamda) is the distance between
two adjacent points on the wave, which have the
same phase. As an example (see figure below) the
distance between two adjacent peaks of the wave.
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
28/10/1431
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Frequency
In a parallel way it is possible to define a wave by its frequency.
Frequency (?) is defined by the number of times that the
wave oscillates per second.
Between these two parameters the relation is:
c = ? * ?
From the physics point of view, all electromagnetic waves are
equal (have the same properties) except for their
wavelength (or frequency).
As an example: the speed of light is the same for visible light,
radio waves, or x-rays.
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
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Wave Description
A wave can be described in two standard forms:
1. Displacement as a function of space when time is
held constant.
2. Displacement as a function of time at a specific place
in space.
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
28/10/1431
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Displacement as a function of space
Displacement as a function of space, when time is "frozen" (held
constant). In this description, the minimum distance between two
adjacent points with the same phase is wavelength (?). Note
that the horizontal (x) axis is space coordinate
A = Amplitude = Maximum displacement from equilibrium.
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
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Displacement as a function of time
Displacement as a function of time, in a specific place in space, as
described in figure. In this description, the minimum distance
between two adjacent points with the same phase is period
(T). Note that the horizontal (x) axis is time coordinate
Dr. Hazem Falah Sakeek www.physicsacademy.org & www.hazemsakeek.com
28/10/1431
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