All-optical data
memory: Ultra-short light pulses make the GST material change from crystalline
to amorphous and
back. Weak light pulses read out the data. (Photo: C. Rios/Oxford University)
(September 23, 2015) Researchers
Develop the First Non-volatile All-optical Chip Memory Based on Phase Change
Materials – Publication in Nature Photonics
The first all-optical permanent on-chip memory has been
developed by scientists of Karlsruhe Institute of Technology (KIT) and the
universities of Münster, Oxford, and Exeter. This is an important step on the
way towards optical computers. Phase change materials that change their optical
properties depending on the arrangement of the atoms allow for the storage of
several bits in a single cell. The researchers present their development in the
journal Nature Photonics (10.1038/nphoton.2015.182).
Light determines the future of information and communication
technology: With optical elements, computers can work more rapidly and more
efficiently. Optical fibers have long since been used for the transmission of
data with light. But on a computer, data are still processed and stored
electronically. Electronic exchange of data between processors and the memory
limits the speed of modern computers. To overcome this so-called von Neumann
bottleneck, it is not sufficient to optically connect memory and processor, as
the optical signals have to be converted into electric signals again.
Scientists, hence, look for methods to carry out calculations and data storage
in a purely optical manner.
Scientists of KIT, the University of Münster, Oxford
University, and Exeter University have now developed the first all-optical,
non-volatile on-chip memory. “Optical bits can be written at frequencies of up
to a gigahertz. This allows for extremely quick data storage by our
all-photonic memory,” Professor Wolfram Pernice explains. Pernice headed a
working group of the KIT Institute of Nanotechnology (INT) and recently moved
to the University of Münster. “The memory is compatible not only with
conventional optical fiber data transmission, but also with latest processors,”
Professor Harish Bhaskaran of Oxford University adds.