The team develops a laser printer for photonic chips
A team of research department led by UW Electrical & Computer Engineering and Physics Professor Mo Li has invented a new way to print and reconfigure photonic integrated circuits (microchips) using a speedy, low-cost device about the size of a conventional desktop laser printer. This device could enable students and researchers to bypass expensive nanofabrication facilities and produce photonic integrated circuits almost anywhere. The technology also has possible industrial applications. Credit: Haoquin Deng | University of Washington
Photonic integrated circuits are an essential next-wave technology. These sophisticated microchips hold the potential to substantially decrease costs and increase speed and efficiency for electronic devices across a wide range of application areas, including automotive technology, communications, health care, data storage, and computing for artificial intelligence.
Harnessing Photonic Circuits for Future Technologies
Photonic circuits use photons, fundamental light particles, to move, store, and access information, just like conventional electronic circuits, which use electrons. Photonic chips are already in use today in advanced fiber-optic communication systems, and they are being developed for implementation in a broad spectrum of near-future technologies, including light detection and ranging, or LiDAR, for autonomous vehicles; light-based sensors for medical devices; 5G and 6G communication networks; and optical and quantum computing.
Cost Barriers in Photonic Circuit Fabrication
Given the broad range of existing and future uses for photonic integrated circuits, access to equipment that can fabricate chip designs for study, research, and industrial applications is also essential. However, today's nanofabrication facilities cost millions of dollars to construct and are well beyond the reach of many colleges, universities, and research labs.
For those accessing a nanofabrication facility, at least a day must be reserved for the exacting and time-consuming lithographic process to make these microchips. In addition, if a design error is made or the chip doesn't work properly for some other reason, the faulty circuit must be discarded, the design adjusted, and a new chip fabricated. This often results in days or even weeks spent in the cleanroom.
Game-Changing Innovation: Photonic Circuitry Anywhere
But now, as described in a new paper in Science Advances, a University of Washington-led research team has devised a way to bypass expensive nanofabrication facilities and produce photonic integrated circuits almost anywhere.
The team has developed an innovative method in which a laser writer can write, erase, and modify these circuits into a thin film of phase-change material similar to what is used for recordable CDs and DVDs. This new process allows photonic integrated circuits to be constructed and reconfigured in a fraction of the time it would take at a nanofabrication lab.
The multi-university team was led by UW Electrical and Computer Engineering and Physics Professor Mo Li, the Department's associate chair for research, a member of the Institute for Nano-Engineered Systems, and the paper's senior author.
Innovation in Education: Cost-Effective Photonic Circuitry
"Photonics technology is on the horizon; therefore, we must train or educate our students in this field. But for students to study and have hands-on experience with photonic circuits, currently, they need access to a multimillion-dollar facility," Li said.
"This new technology addresses that problem. Using our method, photonic circuits that previously had to be fabricated in expensive and hard-to-access facilities can now be printed and reconfigured in labs, classrooms, and even garage workshops by a speedy, low-cost device about the size of a conventional desktop laser printer."
Benefits for students, researchers, and industry
Students aren't the only ones who stand to benefit from this new way of creating photonic integrated circuits. For researchers, this advance will enable a much quicker turnaround time for prototyping and testing a new idea before booking valuable time in a nanofabrication facility.
A significant advantage of this method for producing photonic integrated circuits in industrial applications is reconfigurability. For example, companies could use this technology to create reconfigurable optical connections in data centers, especially in systems that support artificial intelligence and machine learning, leading to cost savings and production efficiencies.
UW ECE's Innovative Photonic Circuit Breakthrough
Li's research team included UW ECE graduate student Changming Wu, the lead author of the paper, and, along with Li, came up with the idea for this novel way of building photonic integrated circuits. UW ECE graduate student Haoqin Deng also contributed to the effort. Their work is the latest result of a six-year line of research at the UW that includes advances in optical computing. It is also a continuation of a productive collaboration with Professors Ichiro Takeuchi and Carlos A. RÃos Ocampo and their students at the University of Maryland.
"Being able to write a whole photonic circuit using only one step, without a complicated fabrication process, is exciting. And the fact that we can modify any part of the circuit in our lab and rewrite and redo it is amazing," Wu said. "It's a matter of minutes versus a full day-long process. It's a huge relief to be able to finish the whole fabrication process within a few minutes instead of what often is several days or even a week."
Improving performance, building a commercial device
The team's method has been proven to work, but it is still an early-stage concept. However, Li has filed a provisional patent application and plans to build a desktop laser writer for photonic integrated circuits. This printer could be sold at an affordable price and distributed widely to research labs and educational institutions worldwide. He is also engaging with industry leaders to promote possible applications of this new technology in programmable photonic chips and reconfigurable optical networks.
Enhancing Photonic Chip Fabrication
This laser printer for photonic chips will use a staging system that will move the substrate much more precisely than a traditional desktop printer. The team will seek ways to optimize its performance as they build a prototype. They will also work on reducing optical loss in their phase-change material through further research in material science and laser writing techniques. This will enable the printer to produce even more detailed and sophisticated circuits.
Li said he and his research team were excited about what lay ahead.
"This technology can create the photonic circuitry you want, but it can also be added onto already-existing electronic circuitry. And because it is reconfigurable and reusable, it opens many possibilities for students, researchers, and industry," Li said. What's most exciting is that we'll potentially have a massive impact on the field of photonics by disseminating this new tool and technology to the broader research community.