International Day of Light - May 16, the UNESCO day marking the anniversary of the first laser
International Day of Light on May 16 is a UNESCO-recognised annual day first observed in 2018 to mark the anniversary of the first successful laser operation by Theodore Maiman on May 16, 1960. Celebrates light science, photonics, and the role of light in technology, culture, and sustainable development. Not a public holiday.
International observancePublished October 14, 2026
- Observed in
- UN
- When
- May
- Frequency
- Same date every year
- Days off
- Varies by country
- Public status
- Varies by country; consult local government gazette
International Day of Light on May 16 is a UNESCO-recognised annual day first observed in 2018 to mark the anniversary of the first successful laser operation by Theodore Maiman on May 16, 1960. Celebrates the role of light science and photonics in technology, culture, and sustainable development. Observed in 80+ countries. Not a public holiday.
The one-line summary
UNESCO-recognised annual day established 2017, first observed 2018, marking the May 16, 1960 first laser. Celebrates photonics, light science, and light-based technology. Observed in 80+ countries. Not a public holiday.
Origin and history
The International Day of Light was established at UNESCO's 39th General Conference in October 2017, proposed by the International Basic Sciences Programme (IBSP) and supported by a coalition of photonics societies including the European Physical Society, the Optical Society (now US), the IEEE Photonics Society, the International Commission for Optics, and the Light Science & Applications journal. The proposal built on the success of the 2015 International Year of Light, which reached over 100 million people across 147 countries.
The day's date - May 16 - commemorates the first successful operation of a laser, achieved by Theodore Maiman at Hughes Research Laboratories in Malibu, California, on May 16, 1960. Maiman's ruby laser produced the first coherent red light beam (694 nm wavelength) and won the race against competing teams at Bell Labs, IBM, and Siemens. The laser's anniversary is now recognized globally as the foundation of modern photonics.
How it is observed
The day is observed through events organized by national chapters of the IEEE Photonics Society, the European Physical Society, the Optical Society (now Optica), the International Commission for Optics, and UNESCO national commissions. Events include public lectures in science museums, light-art installations in cities, photonic technology demonstrations, school visits, and the release of special journal issues.
Major recurring events include the SPIE DCS (Defense + Commercial Sensing) photonics conference, the CLEO Conference on Lasers and Electro-Optics, and the European Optical Society Annual Meeting. Many universities open their photonics labs to school groups on the day; science museums run family-friendly laser demonstrations. The "Light: Beyond the Bulb" exhibition travels between science museums on the day each year.
Photonics applications
Photonics underpins much of modern technology. Fiber-optic communication (which carries over 95% of all long-distance internet traffic), solar photovoltaic cells, LED lighting, medical imaging (endoscopy, OCT), laser surgery, optical clocks (the most precise measurement devices ever built), quantum communication, and semiconductor lithography for chip manufacturing all depend on photonics. The science of light underpins an estimated US$900 billion in annual economic activity.
The first laser
Theodore Maiman built the first working laser at Hughes Research Laboratories in Malibu, California, on May 16, 1960. Maiman used a flashlamp-pumped synthetic ruby crystal (chromium-doped aluminum oxide) to produce coherent red light at 694 nanometers. The paper, published in the British journal Nature on August 6, 1960, was titled "Stimulated Optical Radiation in Ruby." Maiman's laser beat competing efforts at Bell Labs (Arthur Schawlow and Charles Townes), IBM, and Siemens by months.
The laser is now considered one of the foundational inventions of the 20th century, alongside the integrated circuit and the transistor. Charles Townes, who had proposed the laser principle in 1958 with Schawlow, shared the 1964 Nobel Prize in Physics with Nikolai Basov and Alexander Prokhorov (who had independently proposed the maser/laser principle). Maiman's specific contribution was the engineering breakthrough that made the laser work.
Related observances
International Day of Education (Jan 24), World Wildlife Day (Mar 3), and World Water Day (Mar 22) are all UNESCO-recognised days that sit alongside the International Day of Light. The International Year of Light 2015 was the year-long observation that preceded this annual day.
Sources
UNESCO 39th General Conference2017Theodore Maiman, Nature1960IEEE Photonics Society2018SPIE2018Optica (formerly OSA)2018European Physical Society2017