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attract researchers, and educate a much larger generation of PhD students. At the same time, European projects allowed Danish groups to combine their own strengths with fabrication, characterization and expertise elsewhere.
During the 1990s, new microelectronics and photonics facilities expanded what could be made in Denmark, while communications, device and materials research became increasingly connected. These activities were consolidated in 1998 in the Center for Communications, Optics and Materials, COM. By then, the crucial shift had already taken place: Danish optical communications were no longer centered on a few pioneering experiments, but on a durable combination of trained people, research infrastructure, long-term funding and industrial links. This accumulated capability is visible today in industrial facilities for assembling, testing and characterizing photonic devices and systems( Figure 1).
From research capability to specialized industry
By the 1990s, capabilities originally built for optical communications were generating new technologies and companies. A striking example was photonic crystal fiber. At DTU, Anders
Bjarklev, Jes Broeng and colleagues explored how microscopic structures could be used to control the propagation of light in fibers, an idea initially met with considerable skepticism. Collaboration with Philip Russell’ s group at the University of Bath provided complementary experimental expertise and, in 1998, the team reported photonic-band-gap guidance in optical fiber in Science [ 4 ]. The collaboration was followed soon afterwards by the creation of Crystal Fibre and commercialization of photonic crystal fibers around 2000.
The timing could hardly have been worse. Crystal Fibre and the fiber-laser company Koheras emerged just as the telecommunications boom collapsed. Both survived by finding applications where their specialized technologies offered advantages beyond telecom. Photonic crystal fibers enabled broadband supercontinuum sources; Koheras developed highly stable single-frequency fiber lasers. Interaction with researchers and demanding customers helped turn these technologies into products for microscopy, sensing, metrology and, later, quantum applications [ 5; 6 ]. In 2009, Crystal Fibre and Koheras merged to form NKT Photonics, which was acquired by Hamamatsu Photonics in 2024 and renamed Hamamatsu Photonics A / S in 2026 [ 7 ].
Figure 2: Selected companies and organizations illustrating Denmark’ s optics and photonics ecosystem, spanning core industry, research and talent, enabling infrastructure and networks, and application markets. The overview is representative rather than exhaustive.
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