Bio-optical structures and optical waveguides
The most advanced top-down technology for
fabricating a complex optical systems falls far
short when compared with the accomplish-
ments of living organisms at ambient temper-
ature and low pressure (and without clean
rooms)71,72. Several groups have studied bio-
mineralization in diverse marine organisms,
notably the brittlestar Ophiocoma wendtii and
the sponge Euplectella. Some remarkable liv-
ing optical systems have been uncovered, such
as the fiber-optical spicules from Euplectella
that have the dimensions of a single human
hair and can act as multimode waveguides
(Fig. 4). Compared with contemporary syn-
thetic optical fibers, the microfibers are much
nanofibers), have high refractive indices and
considerable flexibility, with the capacity to
act as single-mode or few-mode (where light
waves are effectively confined to the corera
guides when light is coupled to free-standing
spicules. The enhanced refractive-index con-
trast between the spicule and air allows most