May 16, 2021 marks the fourth annual International Day of Light (IDL 2021). Fifty countries have acknowledged their participation in outreach and educational initiatives, and many have already launched their celebrations around the world. The 5th International Jost Bürgi Symposium (Switzerland), an “E-Olympiad” on Optics (Bangladesh), the 1st International Congress of Light and Color Lighting for Ecuador, and an annual event to celebrate the vernal equinox and measure the circumference of the earth using sunlight (Thailand) are just some of the light-themed festivities that have taken place or are ongoing as of May 16. Exhibitions and showcases in Poland, the Philippines, Peru, Pakistan, and more will continue to spread a message of awareness about the benefits of light-based technologies after the sun physically sets on May 16. For those whose work innovates optics and photonics year-round, the IDL provides an opportunity to spread encouragement about the field, its potential, and the plethora of related technologies that benefit from critical research and development. “As we raise awareness about the benefits of light-based technologies, we get a good sense of the vast and impressive breadth of applications that truly can affect people’s lives, from myriad applications of the laser to new technologies resulting from the blue LED,” said Joe Niemela, IDL 2021 co-chair and 2016 recipient of the American Physical Society’s Dwight Nicholson Medal for Outreach recipient from the Abdus Salam International Centre for Theoretical Physics (ICTP). Niemela is cochairing IDL 2021 with John Dudley, 2020 winner of the R.W. Wood Prize of The Optical Society and a professor of physics at the University Bourgogne Franche-Comté. “More than that,” Niemela said, “we also see entrepreneurs around the world who assess local needs and find or create new markets. Much of that is based on trust in the science of light.” Photonics Media connected with some of the volunteers who are supporting IDL events and activities this year by speaking on a wide range of topics, including science, technology, art, culture, education, and development. Maintaining Momentum Roberta Ramponi, director of the CNR Institute for Photonics and Nanotechnologies (IFN-CNR), a physics professor at Politecnico di Milano, Italy, and former president of the European Optical Society, told Photonics Media that IDL 2021 is a critical mechanism for fostering worldwide commitment to the sustainable development in optics and photonics that was brought to the surface in previous years. “Connecting people, although mainly limited to virtual events, and sharing a vision and opportunities has a special meaning this year and allows us to be optimistic and to positively imaging a future age of light,” Ramponi said. Leaders in optics and photonics will use the platform of the IDL to spread awareness of the benefits of light-based technologies. Courtesy of LightDay.org. In addition, Ramponi, International Commission for Optics (ICO) president from 2017 to 2020, said that ICO has joined the “Trust Science” campaign set to kick off on the IDL. “Indeed, the need for trusting science and relying on scientific findings is more important than ever and is crucial to overcome the present situation,” Ramponi told Photonics Media. “Optics and photonics have proven to be throughout the years key enabling technologies, capable of addressing many societal challenges and of targeting most of the U.N. sustainable development goals. Light-based technologies are a key to a future green digital world, thus in a critical period, amidst a global pandemic and related economic crisis threat, they have gained global importance. It is worth noting that they find many applications also in the biomedical and related fields that nowadays is felt as the most crucial.” Jess Wade, from Imperial College London’s Blackett Laboratory, also addressed the importance of facing societal challenges. Discussion about the challenges that face certain communities around the world in their ability to access light, quality physics education, and optics-related research opportunities, Wade told Photonics Media, are an important component of any IDL. Wade has used the IDL platform in previous years to talk about her work on challenging stereotypes, efforts to improve gender balance in physics classrooms, and her research on next-generation OLEDs. This year, she said, the day takes on added meaning given the recent inability for collaboration and idea sharing. “From an engagement perspective, the pandemic has allowed for increased participation of communities who are typically underserved by science conferences and outreach,” Wade said. “It has leveled the playing field for scientists who might not have the opportunity to travel or get visas to attend important science conferences. As more high equality optics and photonics related education materials get shared online, high school students who are not normally excited about their science education get to see how awesome it is.” Extended Limits and Increased Visibility In email correspondence with Photonics Media, Niemela said the ability of optics to serve as an “enabling” science maximizes its potential in advancements that extend into other scientific disciplines, such as physics, chemistry, medicine, and biology. “It can have a relatively low buy-in making it suitable for frontier basic science in low-income countries as well as inviting innovation that comes from mature technologies,” Niemela said, of optics. “The pandemic did not reduce the need for clean water, affordable energy, safe lighting, and other opportunities to make a difference in the lives of people otherwise dealing with COVID-19.” While IDL 2021 specifically will incorporate themes that stem from a year-plus of a global pandemic, the day itself provides an annual platform to spotlight topical and advancing trends. “To me, all kinds of optics and photonics research that challenge our limits in terms of speed, resolution, and distance, as examples, are important,” Rachel Won, Nature Photonics’ international editor, told Photonics Media. “This includes, but is not limited to, research in attosecond photonics, superresolution imaging, optical metrology, as well as fundamental research that helps advance these fields like quantum optics, nanophotonics, plasmonics, metamaterials, and frequency combs.” By spotlighting high-level research and development in these areas, she said, the IDL brings attention to key stakeholders and policymakers, attracting more support and funding and reaching younger generations. The day also provides a chance to introduce the public to established avenues of research, often with widespread appeal. Charles Falco, of the University of Arizona’s Wyant College of Optical Sciences’ Thin Films Group, collaborated with renowned artist David Hockney on a collaboration bridging art and optics. Over the span of several years, Falco and Hockney discovered evidence in paintings, as early as those of Jan van Eyck (circa 1425), that certain artists used optical projects as aids in the production of portions of their paintings. “The sudden appearance of nearly ‘photographic’ realism in paintings early in the 15th century had long been appreciated by generations of art historians, but the reason for the sudden appearance was never adequately explained,” Falco told Photonics Media. “The discoveries resulting from this truly interdisciplinary collaboration between the humanities and sciences showed the explanation was the use of optics.” Public awareness of the project, Falco said, has served as an inroad to optics for many people without a background in the science. “David Hockney is one of the world’s most famous living artists, and more people are interested in what he does than in what most scientists do. As a result, a large swath of the general public has become aware of the discoveries we made about the use of optics by artists as famous as Jan van Eyck, Caravaggio, Holbein, and others. Simply the intrinsic beauty of the famous paintings involved in our discoveries makes most people interested in learning more about them, and the scientific background to our discoveries can be explained to people who do not have a background in optics,” Falco said. The IDL creates an additional forum to share and highlight the work. “I strongly feel that any scientist who is in a position to help the general public understand or appreciate more about science in general is obligated to do so,” Falco said. “Along with this, the IDL is a fantastic mechanism for attracting the interest of the general public to science, because the various aspects of light provides so many entry points to the topic.” How to Participate The International Day of Light is open to all, with registered events planned around the world. Complete information on this year’s program, volunteer speakers, initiatives, and the Trust Science campaign can be found at www.lightday.org, with additional information on Photonics Media’s website.