Reports on Light

Photon Clock: Applied physicists
at the California Institute of
Technology have created a tiny disk
that vibrates steadily like a tuning
fork while it is pumped with light.
This is the first micro-mechanical
device that has been operated at a
steady frequency by the action of
photons alone. Reporting in
recently published issues of the
journals Optics Express (July 11) and
Physical Review Letters (June 10 and
July 11), Kerry Vahala and group
members explained how the tiny,
disk-shaped resonator made of silica
can be made to vibrate mechanically
when hit by laser light. The disk,
which is less than the width of a
human hair, vibrates about 80 million
times per second when its rim is
pumped with light.

Controlling Light: A discovery by
Princeton researchers may lead to an
efficient method for controlling the transmission of light and improve new
generations of communications technologies powered by light rather than
electricity. The discovery could be used to develop new structures that
would work in the same fashion as an elbow joint in plumbing by enabling
light to make sharp turns as it travels through photonic circuits. Fiber-optic
cables currently used in computers, televisions and other devices can
transport light rapidly and efficiently, but cannot bend at sharp angles.
Information in the light pulses has to be converted back into cumbersome
electrical signals before they can be sorted and redirected to their proper
destinations. The results are reported in Aug. 18 issue of Nature.

Controlling Light Speed: A team of researchers from the Ecole
Polytechnique Federale in Lausanne, Switzerland have successfully
demonstrated for the first time that it is possible to control the speed of
light in an optical fiber. Their findings, published in Applied Physics
Letters, could have implications ranging from optical computing to the
fiber-optic telecommunications industry. The researchers were able to
slow light down and speed it up as well. The phenomenon could have
profound technological consequences in controlling the speed of light in a
simple optical fiber.