NTT Labs has succeeded in building a prototype of what the company calls optical random access memory, or short o-RAM.
The idea is to remove the bottleneck between fiber optics and electronic circuits and create a light-speed version of today's DRAM architecture for high-speed data center applications.
According to a research paper published in Nature Photonics, the prototype has a capacity of 4 bits and transfers data at 40 Gbps. It features extremely low power consumption at just 30 nW. While it is far from a commercial product, the researchers believe that it is a foundation for the development of far more capable o-RAM devices with a storage capacity in the range of Kb or Mb. The NTT researchers believe that a 100 Kb o-Ram for all optical network routers device could be built by 2020. A 1 Mb o-RAM chip could be available by 2025.
Each memory cell of the new technology is a nano-photonic crystal that ismade from indium phosphide that integrates a small strip of gallium arsenide phosphide. The flow of laser light is controlled via tiny holes on the outer portion of the cell, while a path in the middle of the crystal was created to allow light to enter and exit the device. Each cell can represent the values 1 or 0 by either transmitting light or blocking it by changing the refraction index of the material. Once a value is set, background light sourced from a laser maintains the refraction index.
The approach apparently enabled the scientists to store data for up to 10 seconds, which is up from 250 nanoseconds in previous similar devices.