Researchers from University of Warsaw have trapped infrared light in a layer just 40 nanometres thick, over 1,000 times thinner than a human hair, using molybdenum diselenide, a material in which light slows 4.5 times. Engineered into a subwavelength grating, it acts as a near-perfect mirror. The setup also boosts infrared-to-blue light conversion by 1,500 times, according to the researchers.