Optical Memory Stores More Data

Researchers demonstrated a new technique for storing more optical data in a smaller space on-chip than was previously possible. This technique improves the phase-change optical memory cell, which uses light to write and read data, and could provide a faster, more energy-efficient form of computer memory.

Researchers describe their new all-optical data storage technique, which could help meet the growing demand for computer data storage.

Their all-optical memory could enable a hybrid computer chip that interacts with data both optically and electrically by bringing the speed of light-based data transmission to the circuit boards that run computers.

The optical memory cell encodes information in a phase change material, used to make re-writable CDs and DVDs. A laser heats parts of a phase change material, causing it to switch between states in which all atoms are ordered or disordered. Because these two states have different optical indices of refraction, light can be used to read the data.

Phase change materials can store data for a long time because they remain in the disordered or ordered state until illuminated again with the specific type of laser light originally used to write the data. Mixing different ratios of ordered and disordered states in an area of the material allows information to be stored in a continuum of levels instead of just zero and one as in traditional electronic memory.

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