Do you think chips will be made of photonic circuits -- instead of
electric -- in the next 20 years?
If you mean a purely optical system, as opposed to having
just pieces here and there rely on some optical phenomenon
(e.g., the "holographic" memory which has been mentioned
here) - no, there is no likelihood of that at all. The reasons
have already been given here, at great length.
Shorter wavelengths usually allow more bandwidth. AFAIK, 400 nm is the
shortest wavelength in which you are safe from ionizing radiation. At
wavelengths shorter than 400 nm, your risk of cancer increases.
Conventional CDs use red lasers. Blu-ray uses 405 nm.
Shorter wavelengths in general permit signals of greater
bandwidth, but the available bandwidth of even infrared
light (longer than 780 nm or so) is so huge already that this
isn't the issue. The reason that Blu-Ray or HD-DVD use
blue lasers is not because of the bandwidth capability
implied by the shorter wavelength, but because it permits
smaller physical structures in the disc to be used for
storage (and hence increases the capacity of the disc per
unit area over their "red-laser" cousins). In other words,
"red" light could easily carry information at the rate necessary
for a Blu-Ray disc; it just can't "see" the disc properly to
read it.
Bob M.
