The invention provides an optical multiplexing and demultiplexing device using
a two-dimensional photonic crystal, in which miniaturization and higher integration
thereof can be achieved; an optical communication apparatus; and an optical communication
system. The optical multiplexing and demultiplexing device of the present invention
includes a substrate; and a plurality of slab layers provided on the substrate.
The slab layers each have a two-dimensional photonic crystal structure, in which
low refractive index regions are periodically arranged. In addition, the slab layers
have line defects, provided in part of the periodical arrangement so as to function
as a waveguide, and at least point defects formed in the respective periodic arrangements,
the point defects capturing light having a specific wavelength and introducing
it to the line defects or capturing light having a specific wavelength from the
line defects and radiating it. The point defects, which capture light having the
same wavelength, provided in the slab layers are disposed so as to oppose each other.
