There is a new breakthrough in microprocessor development, a microprocessor that uses optical connections opposed to electrical wires to transmit data. The electronic-optical microprocessor, developed by MIT, integrates over 70 million transistors and 850 optical components.
The system uses optical fibers, transmitters, and receivers to send data between a processor chip and a memory chip. In a demo, it runs a graphics program to display and manipulate a 3-D image, a task that requires using the internal optical connections to fetch data from memory and run instructions. That boost in bandwidth could save a lot of energy in data centers, says Chen Sun, a researcher at the University of California, Berkeley. He estimates that 20 to 30 percent of the energy used in data-center servers is spent transferring data between processor, memory, and networking cards.
Optical connections can carry more data faster than electrical ones consuming the same amount of power. The data transfers in the prototype occurred at a rate of 300 gigabits per second per square millimeter, which the researchers say is 10 to 50 times the rate for a comparable off-the-shelf electronic microprocessor.
The video provides an animated overview of the chip, description of the test setup for the processor, and a demonstration of the processor running programs.
Credit: Sun et al.
Getting optical components on the same chip as electronics is particularly hard, reports MIT technology review. Researchers have been able to combine only very simple circuits with optical parts, and these systems have remained pricey, says Sun. He and his collaborators hope to keep costs down by manufacturing their devices on existing semiconductor equipment. The prototype chips were made at a working semiconductor manufacturing facility that’s operated by GlobalFoundries in Fishkill, NY. The researchers sent them their designs and then got back their test chips. This fab is of an older generation; making the integrated chips on the state-of-the-art equipment used to make today’s best circuits will require more work.
Achieving an on-chip optical connection between memory and processor using conventional silicon wafers in an ordinary foundry is “a significant technological accomplishment,” says Shayan Mookherjea, an electrical engineer at the University of California, San Diego, who is also developing optical connections for data centers. However, he points out that making the chips this way requires etching off part of the silicon backing that might otherwise allow light to leak out of the working parts of the chip. That could be tricky to do reliably.
Researchers develop ultra-fast light-based microprocessor
