Atom Lasers
He-Ne (Helium-Neon): The Helium-Neon laser was the most common laser
until the spread of diode lasers in the last few years. It was first built in
1961 by Ali Javan. The active medium is a noble gas Neon (Ne), and it is a 4
level laser.
Metal Vapor Lasers
Cu (Copper) Vapor(Lasing action in copper vapor was first demonstrated
in 1966.The first commercial copper vapor lasers appeared around 1980.This laser
was attractive because of its relative high efficiency (up to 1%) for lasers
in the visible spectrum range, and the high pulse power achieved.)
Ag (Gold) Vapor (The Gold Vapor laser is very similar to The Copper
Vapor laser both in structure, and principles of operation. Sometimes, the same
system (laser tube and power supply) is used for both lasers. The only change
is to replace the solid Copper by a wire of pure Gold. The wavelength of Gold
lasers is Red: 628 [nm].)
Molecule lasers
CO2 (Carbon Dioxide) (Lasing action in a CO2 molecule was first demonstrated
by C. Patel in 1964.
He transmitted an electric discharge pulse through pure CO2 gas in a laser tube,
and got a small laser output. CO2 is the gas in which the lasing process occurs,
but other gas additives to the laser tube improve the total efficiency of the
laser. The standard CO2 laser includes in the active medium a mixture of CO2
with N2 and He. The optimal proportion of these 3 gases in the mixture depends
on the laser system and the excitation mechanism.)
N2 (Nitrogen)
Chemical (HF-DF)
FIR - Far Infrared
Eximer Laser
Ion lasers
Ar+ (Argon ion) (The Argon laser was invented in 1964 by William Bridges
at Hughes. Argon ion laser contains a tube filled with Argon gas which transforms
into plasma in an excited state. )
Kr+ (Krypton ion)
Dye laser
Dye lasers are unique in that they are a class of lasers whose lasing
medium is a liquid. Depending on the particular dye used, output can be at a
wide range of wavelengths spanning the visible spectrum and beyond.
Insulator lasers
Ruby(The ruby mineral (corundum) is aluminum oxide with a small amount(about
0.05%) of chromium which gives it its characteristic pink or red color by absorbing
green and blue light. The ruby laser is used as a pulsed laser, producing red
light at 694.3 nm. After receiving a pumping flash from the flash tube, the
laser light emerges for as long as the excited atoms persist in the ruby rod,
which is typically about a millisecond. A pulsed ruby laser was used for the
famous laser ranging experiment which was conducted with a corner reflector
placed on the Moon by the Apollo astronauts. This determined the distance to
the Moon with an accuracy of about 15 cm.)
Ti-Saphire laser(This material is the active medium of the laser called
Titanium doped Sapphire laser. The amount of Titanium ions inside the host material
is about 0.1%, and they replace Aluminum atoms in the crystal.
Ti:Saphire lasers belong to a family of lasers called Vibronic Lasers, in which
trivalent Chromium or Titanium are embedded in solid host, .Ti: Sapphire laser
was first demonstrated in 1982 by Peter Moulton MIT Lincoln Laboratory. Commercial
continuous wave systems entered the market in 1988.)
Semiconuctor lasers
Diodes laser (Semiconductor laser is a laser in which
semiconductor serves as photon source. All diode lasers are built from semiconductor
materials, and all show electric properties which are characteristics of electrical
diodes.)