4. Organic lasers

When Theodore Maiman built the first laser in 1960, producing stimulated emission at 694.3 nm by exciting a ruby (an aluminum oxide crystal Al ₂ O ₃ containing chromium Cr ³⁺ impurities), no one could have imagined the tremendous societal impact this discovery would have. In just a few decades, we've gone from an "invention in search of applications" to an ever-expanding market worth almost $8 billion. While this market is still largely dominated by inorganic lasers,...