Diffraction casting breakthrough could overcome optical computing challenges

On one hand, with the rise of quantum computing, artificial intelligence, blockchain, and cloud gaming, the demand for faster and more powerful computing technology is increasing with each passing year.

On the other hand, the electronic systems that power modern-day computers, gadgets, and high-tech scientific equipment are reaching their theoretical limits in speed and efficiency. This situation indicates the strong need for alternatives to electronic computing.

One such promising alternative is optical computing. While traditional electronic systems employ electrical signals (electrons) to perform computing tasks, an optical system harnesses the power of light (photons) for processing data and performing complex calculations.

Scientists believe that optical computing applications will be much better, faster, and energy efficient than their electronic counterparts. However, currently, many challenges and technical limitations prevent us from realizing this advanced computing technology .

A new study proposes a promising solution to these challenges. The study authors have created a design architecture, called diffraction casting. They claim this method can bring us closer to unlocking the full potential of optical computing .

Diffraction casting is inspired by something from the ’80s

To understand the fundamentals of diffraction casting, one needs to go back to the 1980s when a group of Japanese researchers proposed shadow casting, an optical computing method that utilized large geometric optical patterns to perform simple logical operations.

However, shadow casting required a large setup. Plus, it required precise alignment of its optical components and careful control of light paths, which made it complex and challenging to integrate and use. This method was almost forgotten until recently when the study authors at the University of Tokyo (UTokyo) decided to create diffraction casting, an optical computing method that is inspired by shadow casting.

“We introduce an optical computing scheme called diffraction casting which improves upon shadow casting. While shadow casting is based on light rays interacting with different geometries, diffraction casting is based on the properties of the light wave itself,” Ryoichi Horisaki, one of the study authors and an associate professor at UTokyo, said .

This means that diffraction casting takes advantage of the natural behavior and characteristics of light, such as how it bends, spreads, and interacts with different materials, instead of relying on the physical shapes or structures to manipulate light as in shadow casting.

This difference allows diffraction casting to incorporate flexible and compact optical elements — demonstrating a design architecture that could power practical optical computing solutions . The study authors also successfully tested this optical method for image processing.

“We ran numerical simulations which yielded very positive results, using small 16-by-16 pixel black-and-white images as inputs, smaller than icons on a smartphone screen,” Horisaki said.

Optical computing is not a replacement

The study authors suggest that optical computing isn’t here to replace electronic computing but to work as a parallel technology. This also makes sense as electronic systems serve as foundations of global digital infrastructure.

They are integral to almost every aspect of modern technology — ranging from smartphones to supercomputers .

Moreover, methods such as diffraction casting can overcome various challenges associated with optical computing, but they are still in an early stage. For instance, researchers suggest that diffraction casting itself can take 10 years or more to become commercially viable.

“Diffraction casting is just one building block in a hypothetical computer based around this principle and it might be best to think of it as an additional component rather than a full replacement of existing systems,” Ryosuke Mashiko, lead study author and researcher at UTokyo, said.

Nevertheless, this method is likely to play an important role in enabling optical computing to share the immense workload of electronic systems in areas such as machine learning, cloud gaming , and quantum computing.

The study is published in the journal Advanced Photonics .