[Image above] Credit: Britanka, GoodFon
In our push to electrify everything, we need to consider the limits of our current infrastructure to handle the increase in global energy demand. In the U.S., as of 2023, 70% of lines and transformers were more than 25 years old. As equipment ages, it becomes less efficient. Transitioning to an all-electric power consumption model, then, will require increased generating capacity through the construction of new energy infrastructure. But it will also require the development of more energy-efficient devices to reduce energy consumption and achieve the same level of automation.
Currently, consumer and industrial electronics require approximately 20% of global energy production. Most of today’s electronics rely on solid-state technology, including the large-scale data centers required for modern computing as well as the supervisory control and data acquisition systems that control our transportation systems, electrical power grids, and manufacturing facilities.
Solid-state computing relies on electric signals and the physical properties of materials to transmit energy. It produces heat and requires cooling, which places strain on our environment. Data center cooling alone consumes as much as 40% of their total energy use. The expansion of artificial intelligence applications is only increasing these energy needs.
Finding a way to reduce the energy consumed by electronics would be a huge breakthrough in sustainability. One possible way to do that is with photonic computing.
What is photonic computing?
Photonic computing, also called optical computing, harnesses photons, the fundamental particles of light, to process data at close to the speed of light. These systems far exceed the capacity of solid-state systems because they can process multiple wavelengths of light simultaneously, which enables high-bandwidth communication.
In addition to facilitating faster data transfer, photonic devices consume less energy and generate less heat than solid-state devices, all key factors in improving the energy efficiency of systems powered by artificial intelligence. Plus, photonic computing can potentially advance image processing and analysis capabilities considerably by removing the need for optical-to-electrical conversions.
The materials used in photonic devices play crucial roles in their performance, efficiency, and scalability. Unsurprising to the readers of this blog, ceramic and glass materials can meet many of these material requirements.
Ceramic and glass materials used in photonic computing
Glass optical fibers have a long history in communication and electronics. They came to prominence more than 50 years ago when the Corning Glass Works broke the attenuation barrier by doping silica glass with titanium. We owe today’s internet to this development.
Currently, optical fibers are mostly used to transmit light over long distances. But in photonic computing systems, optical fibers act as the circuit pathways for light-based computation, allowing for parallel data manipulation.
Though optical fibers today are mainly made from glass, emerging research on crystalline optical fibers could enable enhanced performance metrics. Ceramics such as sapphire and yttrium aluminum garnet are often used in these experiments, but challenges with fabrication limit upscaling and commercial application.
The use of ceramics for other components, though, is established practice. For example, waveguides are needed to channel the light signals in photonic computing. Indium phosphide, gallium arsenide, and silicon oxynitride are used as waveguide materials.
Ceramics such as yttrium aluminum garnet are also used as the laser gain medium, which amplifies light through stimulated emission. This process produces the high-intensity laser beams needed for optical communication and materials fabrication processes, among other photonic applications. Recent research has looked at using light-emitting diodes in place of lasers, but this work is not well developed.
Nonlinear optical ceramics can be employed in frequency conversion processes, allowing for the generation of new wavelengths of light. This process is crucial for applications such as wavelength multiplexing in photonic circuits.
Looking to the future of photonic computing systems, photonic crystals are optical nanostructures that are starting to be explored for these different components as well. Some recent studies on fabricating ceramic photonic crystals can be found here, here, and here.
Challenges and future directions for photonic computing
Although photonic computing is a promising alternative to solid-state computing systems, there are challenges to overcome.
- Integrating photonic systems with existing electronic systems is complex, making the development of hybrid systems a significant hurdle. Given the ubiquity of existing systems, this issue is a notable concern.
- Some photonic materials, such as crystalline optical fibers, may not scale well, hindering large-scale production. Conversely, materials such as barium titanate or lithium niobate, which are used in photonic circuits, must be optimized to overcome scattering and absorption issues or unstable ferroelectric properties to reach efficiency targets.
- The fabrication of photonic devices is expensive, particularly for advanced materials and complex structures. In addition, use of this technology for high-speed data processing is still in its infancy. Commercially viable solutions may be a decade away.
Once these challenges are overcome, I suspect that photonic computing will be adopted first for large-scale applications, such as data centers and artificial intelligence. These powerful, efficient, and low-energy systems would be immediately useful for such settings that require high computing capacity with limited interconnections to other systems.
Conclusion
Ceramic materials are integral to the advancement of photonic computing. Their unique properties suit them to applications ranging from waveguides to optical fibers. As research continues to address the challenges associated with their use, ceramics will remain a cornerstone of future photonic technologies, driving the next wave of computational advancements. Ceramic engineers have a vital role in this progress, paving the way for innovative solutions that harness the power of “star stuff” (as Carl Sagan would say).
By embracing these opportunities, the ceramics community can contribute significantly to the burgeoning field of photonic computing, helping to shape a future where light, rather than electricity, powers our information systems.
If you are interested in this topic, consider registering for Symposium 17 at the upcoming 49th International Conference and Expo on Advanced Ceramics and Composites, which will be held in Daytona Beach, Fla., in January 2025.
Further reading
Dong, B.W., et al. “Partial coherence enhances parallelized photonic computing,” Nature 2024, 632: 55–62.
Chattaraj, S., Guha, S., and Galli, G. “First-principles investigation of near-field energy transfer between localized quantum emitters in solids,” Physical Review Research 2024, 6: 033170
Maring, N., et al. “A versatile single-photon-based quantum computing platform,” Nature Photonics 2024, 18: 603–609.
Rastogi, V. and Chaurasia, S. “Advances in and future perspectives on high-power ceramic lasers,” Photonics 2024, 11(10): 942.
