
                     Japan Pursues Optical Chips
                     ---------------------------


   Japan has embarked on a 10-year project to develop integrated circuits
that incorporate lasers, light sensors, and transistors all on the same
chip.  The goal of the 10-billion-yen ($65 million) program is to make an
opto-electronic IC (OEIC) containing 20-30 lasers, each capable of
switching on and off 10 billion times a second, according to Tatsutoku
Honda, a director of the government-backed Optoelectronic Industory and
Technology Development Association.

   Such chip could serve in proposed optical computers capable of working
1000 times faster than today's electronic ones.  Closer at hand - probably
within five years, says Honda - is a single-chip repeater for long
distance fiber optic links.  A detector on one side of the OEIC could
convert light signals from an input fiber into electrical from; after
amplification by a transistor on the chip, the resulting current would
modulate a laser connected to the chip's output fiber, allowing the
optical signals to continue on their journey with renewed intensity.
OEICs could also enable graphic data to be transmitted all at once instead
of being converted into a bit stream; a laser array on one chip would
light up to display an image that would then be read by a sensor array on
the receiving chip.

   The project, spearheaded by the newly formed Optoelectronic Technology
Research Corp., faces major challenges.  Making a high density OEIC, for
example, will mean shrinking diode lasers from their present length of 300
microns to about 1 micron.  And while electronic circuits run in sillicon,
most optical devices are based on gallium arsenide or indium phosphide,
which require different fabrication techniques.  The Japanese are focusing
on technologies (such as metal-organic chemical vapor deposition) that can
marry these dissimilar materials.
