The blue area is meant for the optical signals, which the yellow areas are copper wire carrying electrical signal. Both technologies are integrated on the same chip. (via IBM)


Electrical signals travel anywhere between 40% to 95% of the speed of light. A typical twisted pair telephone line signal, for example, is somewhere in the 40-70% range.



What would happen if a data signal could travel uninhibited at the full speed of light? The innovators at IBM have long pondered that very question, spending the past 10 years trying to find and develop ways to integrate photon circuitry into the age of computers. Their result is something called nanophotonics. Not only have they already proven the concept back in 2010 with nanophotonic CMOS, but now they have found a way to manufacture nanophotonic chips at conventional semiconductor foundries where conventional CMOS are made. This means a lower cost for production, and more excitingly, these chips are ready for manufacturing.



IBM is developing the first 90nm fabrication line to produce these chips. By adding processing modules to existing CMOS fab lines, electrical and optical components are built onto the same chip. IBM has already manufactured modulators, germanium photodetectors and ultra-compact wavelength-division multiplexers that can be integrated with good ol’ analog and digital CMOS.



Cross-sectional view on the nanophotonic chip. The Red rectangles in a photodetector and the Blue ones are modulators. This view shows the nine layers of copper interconnects. (via IBM)


The advantages of nanophotonic are vast. One can produce faster communication between chips, as these pulse beams of light back and fourth, no matter what distance between these components. These light-ways will clear up electrical signal traffic that happens at junctions and interconnections like the huge amounts found in servers, data centers or supercomputers. IBM says that one nanophotonic channel CMOS can transfer data at 25Gbps. Parallel signals can be combined with an on-chip wavelength-division multiplexing device to transmit every signal through one optical fiber. The company claims this process could allow speed of terabytes per second.



Dr. Yurii A. Vlasov, manager of the Silicon Nanophotonics project at IBM Research said that 90nm fab line being built will meet the performance requirements for optical communications in the next decade at a low cost. However, there has been no news of the cost a silicon nanophotonic chip will cost or when exactly they will be released. After IBM is done building the 90nm fab line, most likely.



(For those who don't now, the speed of the actual electrons, known as drift speed, is somewhere in the millimeters per second. An electrical signal acts like sound vibrating air molecules to the electrons.)