Successfully manufactured the first optical-electronic chip in the world

A common electronic processing chip will have limits on speed and operating temperature, so long ago researchers have been working to make a chip that works with light to solve the same problem. at all the above issues.

Moving data inside a computer means pushing those digital signals through electrical wires, with narrow bandwidth limits and also generating lots of heat. However, when the data is posted on the internet, those digital signals will be run in optical fiber segments, with the ability to travel far and huge bandwidth without the need for a factory. Atomic power to power that system.

The contrast between these two methods has led most companies to find ways to bring optical connections into the computer, and ultimately within the chips themselves. This poses a significant challenge for researchers. Although current technology allows the use of light-capable silicon, such processors are not compatible with CMOS technology used in electrical circuits. As a result, most efforts in this area must use two separate chips, a chip for the common processor, another chip for optical connectivity.

Electronic processing chip.

But now a team has succeeded in creating a single chip that can handle both optical and electrical connections, and is connected to the main optical memory. Although the bandwidth is still relatively low, the entire system has been manufactured using standard CMOS chip processes, so manufacturers will not have to change a new process to produce the chip. The chip is integrated with a small processor, with RISC architecture, to provide the ability to run standard documents and graphics programs.

Principle of new optoelectronic chip

Although there are many similarities, one difference of this chip with previous efforts is the emergence of laser sources. It is a separate hardware, with output light directed at the inside of the chip. However, when light reaches the chip, every part to handle that light, must be made of silicon. These parts include waveguides to direct light to a specific location, optical modulators to split the light into bits, and optical detectors to record these bits. .

In this case, the laser is a light source at an 1180 nanometer light wavelength. That's the frequency that can pass through silicon, but the researchers made some modifications to change the properties of the laser. For example, a silicon-germanium alloy can act as a light detector, receive photons and convert them into electrical impulses.

The effort to combine electronic chips and optical chips on a single chip requires researchers to envision a variety of different approaches to working on a limited space. For example, how to fix the material around the material so that light, through silicon waveguides, enters the surrounding material area. The performance of modulators varies with temperature, which varies with the amount of data that the chip must process. Therefore, the researchers created an information feedback system to detect the decrease in light intensity, and activate the resistor thermistor to keep the temperature at the required level.

Test results

With all of the issues handled, the authors of the project were able to make a chip, combining electronics and photonics, including 70 million transistors and 850 photonic components. The processor itself is a dual-core chip, with RISC-V architecture, an architecture that has been used by researchers, because it is suitable for the ability to operate at Gigahertz frequency. Memory is a separate chip, placed at an arbitrary distance, but limited by fiber length.

One difference of this chip with previous efforts is the emergence of a laser source.

Both processor and memory chips have three external optical transitions. The first transitional layer simply receives light from a laser light source. The second transitional layer serves to transfer data from the processor chip to the memory chip. The third layer will transfer the data back from the memory chip to the processor chip. Each path in these links has a bandwidth of up to 2.5 Gb / s, creating an aggregate bandwidth of up to 5 Gb / s. That bandwidth is equivalent to the current phone memory bandwidth and is also much lower than with optical systems, so there is still a lot of work to do. When the processor chip is locked, it does not allow access to the core of the memory, which means that the processor will be braked at 31Mhz, when only using optical memory.

Anyway, the system really works. As the video above shows, optical buses can support everything from simple "hello world" programs to complex programs to extract a teapot in 3D images.

While there is still a lot of work to do to bring this technology to its full potential, optical hardware has begun to move closer to becoming a CPU, based on separate optical chips. The next step is to start linking the hardware inside these chips together, through optical connection cables (rather than copper wires), and some companies have begun testing this hardware system. . The next step is to have a new storage system for these optical connections, before deploying the next work.

Either way, this study is indeed making significant progress. However, this is also an early step for a problem, which we don't really need to solve right away. However, by identifying an approach through CMOS technology as well as constraints and deadlock issues, the team was able to set the path that would take us where we want to go.