Every year on 16 May UNESCO calls for the International Day of Light. The young tradition underlines the outstanding role of light as a tool for modern societies. Behind it are many clever minds from early history to the dawn of quantum technology.

UNESCO International Day of Light zoom

Since early history man has used sunlight to measure time, since the 13th century (B.C.) with sundials.

In the 16th century (A.D.) Galileo Gallilei and Ole Rømer calculated how fast light propagated. A hundred years later, Isaac Newton suspected particles in light.

Christiaan Huygens opposed this premonition of photons with the wave theory of light.

Around 1850 Michael Faraday discovered the magneto-optical effect and James Clerk Maxwell proved that light must be electromagnetic waves.

At the beginning of the 20th century, however, Albert Einstein and Max Planck doubted wave theory when they came across the photoelectric effect. With light, electrons could be released from bonds. The electron absorbs a photon whose energy corresponds at least to its bond energy. For Einstein and Planck it was clear that light must consist of waves and particles. This wave-particle dualism is regarded as the nucleus of quantum physics.

Einstein also invented the theory of induced emission of light in 1916.

This theoretical basis of the laser made Theodore Maiman true in 1960 in the form of a ruby laser. Weeks later a helium-neon based gas laser by Ali Javan, William R. Bennett and Donald R. Herriott followed. Since then, the variety of gas and solid-state/semiconductor lasers has increased rapidly.

In the 1980s and 1990s, ultrashort pulse, disk and fiber lasers matured. Today, light is an indispensable tool for industry, medicine and research—and is regarded as one of the most important and dynamic fields of innovation in modern societies.

Quantum technology—the next revolution


The Physikalisch-Technische Bundesanstalt Braunschweig (PTB) is currently researching the most accurate clock in the world. Prof. Piet Schmidt provides insights into the daily research work and visions of quantum technology in the field of photonics. Also at LASER World of PHOTONICS 2019 in Munich there will be exciting supporting program items on this megatrend.

As the world's leading trade fair, LASER World of PHOTONICS is both a mirror and a driver of innovation. Be there from June 24 - 27, 2019, when photonics sets new milestones and opens a new chapter in the long history of light with quantum technology.

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