A device that unites multiple optical signals to transmit through a
single optical fiber, or splits the united signals.
In optical fiber transmission, the technology that allows multiple optical
signals to transfer in a single optical fiber is necessary. For this purpose,
various types of multiplexer-demultiplexers are studied and fabricated
with diffraction grating, prism, interference filter and so on. Micromachining
technology is expected to make the system that joins such devices to optical
fibers, as well as to reduce size of the devices themselves.