The interference of light is one of the most important optical
phenomena in the ﬁeld of bionanophotonics. At ﬁrst, we will
summarize its features for the convenience of the later discussion.
The interference is a phenomenon, in which waves of more
than two are superposed together to cause various patterns in
temporal and spatial domains. Since it is based on the superposition
principle described in the previous section, and most of interesting
phenomena appearing in bionanophotonics originate from this
simple principle, here we will consider it generally.