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Researchers developing chip with integrated optical communications
Researchers from several US universities have created a chip with optical elements and traditional processor elements with transistor technology are united. The chips can optically communicate with each other.
The “hybrid” chips are one of the first widely producible chips called silicon photonics technology. Thus, the integration of optical communication elements such as lasers, waveguides and photodetectors with CMOS technology meant. That would have the advantage of chips with optical signals over much more bandwidth with lower energy costs, and can communicate with each other than with electrical signals is possible. Of course, optical elements exist for data transmission via light for some time, but this technique is not compatible with chip manufacturing techniques such as those used for processors or memory. Various attempts have been made to integrate the incompatible crystal structures for optics and transistors.
The researchers from the Universities of California, Colorado and MIT have chosen a different approach: they started from standard fabrication techniques for producing the integrated transistors and lasers to semiconductor technology. So they were able to produce chips processor cores, have memory and optical components. Because standard manufacturing techniques were used, complex chips could be built: the test chips contain 70 million transistors and more than 850 optical components. Thus, the complexity of the chip is compared with a Pentium 4 processor.
The chip is composed of three to six millimeters from two risc-V cores are clocked at 1,65GHz and each have 56KB L1 cache. The onboard memory is composed of 1MB of memory. The optical part of the chips is divided into three sub-areas: a test area and two transceiver banks, one for the memory and one for the processor. Each transceiver bank consists of two parts, with eleven eleven receivers and transmitters. As a demonstration, the researchers constructed an arrangement with two chips, which are connected to optical interconnects.
The one is configured as a memory chip, while the second was used as the processor. By using the optical link, the processor chip used so the memory of the second chip. As a light source using an external laser which was fed to each of these chips, and was processed by onboard modulators and filters. The communication signals between the two chips were strengthened through additional external amplifiers. If test program was run memtest and among other things was also run a memory intensive rendering test. The theoretical bandwidth for sending and receiving respectively 550Gbps and 900Gbps. The researchers believe their technique without many problems can be scaled up for commercial production of processors that communicate with light.
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