  We report a detailed ab initio investigation on the optical properties of ice
under a wide high pressure range. The ice X phase (up to 380GPa), the
theoretical proposed higher pressure phase ice XV (300GPa), as well as the
ambient pressure low-temperature phase ice XI are involved. Our results show
that the dispersion relations of optical properties of ice under high pressure
are quite different from those under ambient pressure. Under higher pressure,
there is whole tendency of blue shift in all optical properties of ice, and the
energy region for optical response become broader, such as the absorption band
and reflection band. In addition to the augmented absorption edge, all
absorption peaks are found to be rising, and the reflection peaks are also
enhanced a bit; hence the transmissivity of ice is inferred to be dropping. The
photoconductivity is enhanced, and we explain this behavior from the increase
of earner density. The static optical properties are found to be pressure
independent, and principally due to the network topology of hydrogen bonding.
