When most of us think about lasers, we never even stop to wonder if there are different types of lasers. We kind of just assume that a laser is a laser, like a peanut is a peanut. This assumption however is false. There are many different types of lasers and a new one has just been developed.
Image: The laser
A Princeton-led team of researchers has discovered an entirely new
mechanism for making common electronic materials emit laser beams. "This discovery provides a new insight into the physics of lasers,"
said Claire Gmachl, who led the study. Gmachl, an electrical engineer,
is the director of the Mid-Infrared Technologies for Health and the
Environment (MIRTHE) center. The phenomenon was discovered in a type of
device called quantum cascade laser, in which an electric current
flowing through a specially designed material produces a laser beam.
Gmachl's group discovered that a quantum cascade laser they had built
generated a second beam with very unusual properties, including the
need for less electrical power than the conventional beam. "If we can
turn off the conventional beam, we will end up with a better laser,
which makes more efficient use of electrical power," said Gmachl.
So basically what was discovered was a new layer of lasers. One that we have never be able to make use of before, but that could have a potential cost savings in power consumption. It's kind of like lasers and going green.
What exactly is a laser anyway?
Well, the scientific explination goes a little bit like this. The light emitted by a laser differs fundamentally from light produced
by common sources such as the sun, fire, or electric lamps. According
to the field of physics called quantum electrodynamics, light is made
up of particles called photons. Common sources of light emit photons
that are in a random order, like crowds milling about a busy
marketplace. In contrast, photons in a laser are "in sync" with each
other, like a music band marching in formation. This property, called
coherence, allows laser light to shine in an intense, narrow beam of a
single, very pure color.
Where can this new laser find a home outside the lab?
Unlike other lasers, quantum cascade lasers operate in the mid- and
far-infrared range, and can be used to detect even minute traces of
water vapor, ammonia, nitrogen oxides, and other gases that absorb
infrared light. As a result, these devices are finding applications in
air quality monitoring, medical diagnostics, homeland security, and
other areas that require extremely sensitive detection of different
chemicals. The new discovery should help make these devices smaller,
more efficient, and more sensitive, said Gmachl.