ananyo writes "Bits of data travelling the internet have a tough commute — they bounce back and forth between optical signal lines for efficient transmission and electrical signal lines for processing. All-optical routers would be more energy efficient, but their development has been hindered by a lack of optical memory devices. Now, researchers have developed just such a device (journal article abstract), paving the way towards a faster, more energy-efficient internet. The devices are based on optical cavities that can be switched between light-transmitting and light-blocking states to construct digital signals. Researchers have been working on such devices for several years, but previous versions used too much power and could not retain data long enough. The new memory cells use just 30 nanowatts of power, 300 times less than previous designs, and can retain data for one microsecond — long enough to support processing."
(See also this paper on all-optical swtiches
by four of the same authors.)