Information Technology Reference
In-Depth Information
Fig. 3.34 Memory based
on the “hole burning” effect
engineering assessment of the feasibility of creating extra high-capacity memory
based on the “hole burning” effect were conducted (Fig.
3.34
). Consideration was
given to the option in which chips of 1 cm
2
with the record density of 106 bits/cm
2
were grouped into subsystems containing 16-64 chips, for a total capacity of
2.8 GB. 50-1,000 of such subsystems, in their turn, formed a memory with up to
8 TB of capacity.
It was suggested to use a sodium fluoride crystal with color centers, in which
holes of 50 MHz in width could be burnt in the band with a maximum of 575 nm
and a width of 100 GHz (~0.1 nm). Later it was reported that a new group of
materials for frequency-selective recording of information was discovered—the
crystals of fluorides of alkaline elements in which ions of rare earth elements and
special glasses based on one of the boric acids were introduced, with embedded
carbazole molecules. This storage medium had to be kept at the temperature of
liquid helium. The studies demonstrated that there were no technical constraints to
the creation of such a system with record characteristics for that time. However,
operational characteristics of this device were not satisfactory. One problem was
the helium temperature required for storing information. Furthermore reading and
writing speed was inadequate even for that time. With a maximum speed of
recording of one hole of 30 ns, it took 30 s to record 1 GB.
