A miniature prison for photons—that is the nanocavity discovered by scientists of the University of Twente. It is an extremely small cavity surrounded by an optical crystal, a structure of pores etched in two perpendicular directions. Confining photons in this 3-D cavity may lead to tiny and efficient lasers and LEDs, storage of information or ultrasensitive light sensors. The results are published in Physical Review B, one of the journals of the American Physical Society.