Due to the proliferation of broadband services in
recent years, the volume of information transmitted
across the Internet is growing steadily. As a result, data
processing capacity of information processing systems
are expected to significantly increase. Signal processing
in an information processing system can be classified as
between equipment, between boards inside the equipment,
and between chip and module inside the board. Currently,
the use of optical fibers and optical waveguides are on
the rise for inter-equipment and in some cases interboard
connections. The use of electrical wirings to make
high-speed connections between the closely spaced
chips in the board poses problems of noise interference,
number of wirings and wiring size. Furthermore, judging
from the yearly increases in information traffic, electrical
wirings will no longer be adequate for interconnections,
thereby raising the expectations of optical interconnection
technologies.