Transcript Introduction to Nonlinear Optics

A Short History of Laser
H. R. Khalesifard
Institute for Advanced Studies in Basic
Sciences
Email: [email protected]
Stimulated emission, The MASER
and The LASER

(1916) The concept of
stimulated emission
Albert Einstein
E2  E1  h
E2
h
Absorption
h
h
E1
E2
E1
Spontaneous
Emission
h
E2
E1
Stimulated
Emission
h

(1928) Observation of negative absorption or
stimulated emission near to resonant wavelengths,
Rudolf Walther Ladenburg
h
h
E2
h
E1
Stimulated Emission
(negative absorption)
E2, N2
h
Absorption

h
h
E1, N1
E2, N2
h
E1, N1
Stimulated
Emission
(1930s) If a physical system be in thermodynamic
equilibrium the population inversion and so the stimulated
emission is impossible
Light (Microwave) Amplification
by
Stimulated
Emission of Radiation
LASER
(MASER)
The Maser
Left to right: Prokhorov, Townes and Basov at the
Lebedev institute (1964 Nobel prize in Physics for
developing the “Maser-Laser principle”)
Townes (left) and
Gordon (right) and
the ammonia maser
they had built at
Colombia University
The LASER
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(1951) V. A. Fabrikant “A method for the amplification of
electromagnetic radiation (ultraviolet, visible, infrared, and radio
waves)” patented in Soviet Union.
(1958) Townes and Arthur L. Schawlow, “Infrared and Optical
Masers,” Physical Review
(1958) Gordon Gould definition of “Laser” as “Light Amplification
by Stimulated Emission of Radiation”
(1960) Schawlow and Townes
U. S. Patent No. 2,929,922
(1960) Theodore Maiman Invention of the first Ruby Laser
(1960) Ali Javan The first He-Ne Laser
Arthur Schawlow adjusting a ruby laser that he
made at the Bell Labs in 1960
Maiman
and the
first ruby
laser
Ali Javan and
the first He-Ne
Laser
The laser cavity length should be
multiple of light wavelength
The laser Structure
End Mirror
Pump
Front Mirror
Lasing Medium
Properties of Laser Beam
A laser beam
 Is monochrome
 Can be focused in a very small point
 Is intense
 Is Coherent
 Has a very low divergence
 Can be compressed in time up to few femto
second
Applications of Laser


(1960s) “A solution looking for a
problem”
(Present time) Medicine, Research,
Supermarkets, Entertainment,
Industry, Military, Communication,
Art, Information technology, …