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The objective of this work was to develop a
faster, more efficient data switch for use in optical
communications networks and optical signal processing
systems. An optical device has been developed to
perform ultrafast, all-optical switching by using light
bullets to switch light bullets. This invention was
granted U.S. Patents 5,651,079, July 22, 1997 and
5,963,683, October 5, 1999; it was based on computer
simulations of the interactions of light bullets.
The rapid proliferation of information technology
in commerce, finance, education, health, government,
security, and entertainment, together with the
ever-increasing power of computers and data storage
devices, is fueling a potentially massive demand for
network interconnections, especially broadband
services. Switching is an essential operation of all
communications networks and digital computers and
signal processing systems. Switching is presently a
limiting factor in the speed of operation of optical
communications and computing, because most
commercial devices must use electrical forms of
switching, and in the longer term electronic systems
will become increasingly complex and costly.
Network designers will turn increasingly to photonic
transport and switching technologies. An all-optical
switch would have the inherent advantages of higher
speed and higher efficiency.
One such all-optical switch has been designed at
Ames Research Center. In the NASA switch configuration,
light bullets propagate through, and interact
nonlinearly with, each other within a planar slab
waveguide to selectively change each other's directions
of propagation into predetermined output
channels. The resulting performance should enable
low-power, high-speed switching in a small device.
Possible materials include nonlinear glasses,
semiconductor crystals, and multiple quantum-well
semiconductors. The patents describe the necessary
material parameters, including negative group
velocity dispersion, nonlinear index of refraction, and
wavelength of light, that are required in order for the
light bullets to interact and selectively change each
other's direction of propagation.
The figure shows the results of a computer
simulation of two counter-propagating light bullets at
four instants in time. As they collide with each other,
they deflect each other through attraction. This
deflection is the basis of a light switch, that is, where
light switches light.
Point of Contact: P. Goorjian
(650) 604-5547
goorjian@nas.nasa.gov
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Fig. 1. Collision of two counter-propagating
light bullets.
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