Ferris Jabr, New
Scientist, 12 June 2011
Ed. Note: The discovery
of the first human cellular laser proves to the
bioelectromagnetics practitioner that light is not
only "compatible" with endogenous cellular
metabolism but the orders of magnitude increase in
the energy density of visible light from the
lasing cavity inside the cell is also tolerable
and therapeutic to the cell. See the reference
book, Bioelectromagnetic Healing for
a scientific explanation of "light therapy" and
details on how electromagnetic fields of all
frequencies interact with human
The human kidney cell that was used
to make the laser survived the experience. In
future such "living lasers" might be created
inside live animals, which could potentially allow
internal tissues to be imaged in unprecedented
It's not the first unconventional
laser. Other attempts include lasers made of
Jell-O and powered by nuclear reactors (see
Related Information box below). But how do you go
about giving a living cell this bizarre
Typically, a laser consists of
two mirrors on either side of a gain medium - a
material whose structural properties allow it to
amplify light. A source of energy such as a flash
tube or electrical discharge excites the atoms in
the gain medium, releasing photons. Normally,
these would shoot out in random directions, as in
the broad beam of a flashlight, but a laser uses
mirrors on either end of the gain medium to create
a directed beam.
As photons bounce back and forth
between the mirrors, repeatedly passing through
the gain medium, they stimulate other atoms to
release photons of exactly the same wavelength,
phase and direction. Eventually, a concentrated
single-frequency beam of light erupts through one
of the mirrors as laser light.
Alive and well
Hundreds of different gain media
have been used, including various dyes and gases.
But no one has used living tissue. Mostly out of
curiosity, Malte Gather and Seok-Hyun Yun of
Harvard University decided to investigate with a
single mammalian cell.
They injected a human kidney cell
with a loop of DNA that codes for an enhanced form
of green fluorescent protein. Originally isolated
from jellyfish, GFP glows green when exposed to
blue light and has been invaluable as a biological
beacon, tracking the path of molecules inside
cells and lighting up when certain genes are
After placing the cell between
two mirrors, the researchers bombarded it with
pulses of blue light until it began to glow. As
the green light bounced between the mirrors,
certain wavelengths were preferentially amplified
until they burst through the semi-transparent
mirrors as laser light. Even after a few minutes
of lasing, the cell was still alive and well.
Christopher Fang-Yen of the
University of Pennsylvania, who has worked on
single-atom lasers but was not involved in the
recent study, says he finds the new research
fascinating. "GFP is similar to dyes used to make
commercial dye lasers, so it's not surprising that
if you put it in a little bag like a cell and pump
it optically you should be able to get a laser,"
he says. "But the fact that they show it really
works is very cool."
Yun's main aim was simply to test whether a
biological laser was even possible, but he has
also been mulling over a few possible
applications. "We would like to have a laser
inside the body of the animal, to generate laser
light directly within the animal's tissue," he
In a technique called laser
optical tomography, laser beams are fired from
outside the body at living tissues. The way the
light is transmitted and scattered can reveal the
tissues' size, volume and depth, and produce an
image. Being able to image from within the body
might give much more detailed images. Another
technique, called fluorescence microscopy, relies
on the glow from living cells doped with GFP to
produce images. Yun's biological laser could
improve its resolution with brighter laser
To turn cells inside a living
animal into lasers, they would have to be
engineered to express GFP so that they were able
to glow. The mirrors in Yun's laser would have to
be replaced with nanoscale-sized bits of metal
that act as antennas to collect the light.
"Previously the laser was
considered an engineering material, and now we are
showing the concept of the laser can be integrated
into biological systems," says Yun.
The living laser is a first, but
other strange lasers have been made in the
half-century since Theodore Maiman made the first
such device from a fingertip-sized ruby rod. On 16
May 1960, Maiman blasted the ruby with a brilliant
burst of light from a photographic flash lamp,
generating a bright red beam.
About a decade later, two future
Nobel laureates created the first edible laser -
well, almost. Theodor Hänsch and Arthur Schawlow
tried 12 flavours of Jell-O dessert before
settling on an "almost non-toxic" fluorescent dye.
When added to unflavoured gelatin, this yielded a
bright laser beam when illuminated with UV light.
Schawlow, who had snacked on the failures, gave
the successful one a miss.
Around the same time, NASA wanted
much more powerful lasers for beaming power into
space, and proposed powering these by exciting
molecules with fragments from nuclear fission
inside a small reactor. Pulses of up to 1 kilowatt
were achieved before NASA abandoned the programme.
The so-called Star Wars programme of the Reagan
era later funded a project to develop
reactor-powered laser weapons, but they never got
off the ground.
Much more recently, in 2009, the
world's smallest laser was demonstrated at the
University of California, Berkeley. It generated
green laser light in strands of cadmium sulphide
only 50 nanometres across, 1/10th of the
wavelength of the light it emitted.
And don't forget the anti-laser,
from Hui Cao's lab at Yale University. Instead of
emitting light, the anti-laser soaks it up.
Strange as it sounds, it may have a practical use:
converting optical signals into electrical form
for future communication links. Jeff Hecht
Nature Photonics, DOI: