A random laser like this one made of millimeter-sized spheres glows with laser-like light. New results suggest that their flashes of monochromatic light are initiated by a very few photons that remain inside the material for a long time. Image Credit: D.S. Wiersma/LENS/INFM
Somewhere between a light bulb and a laser is an unusual and sometimes puzzling type of light source called a random laser. It emits laser-like light, but in all directions. Now a research team believes they understand one of the mysteries of random lasers: why they can emit blasts of monochromatic light as pure as those of an ordinary laser. Their experiments and computer simulations show that each pure pulse begins as a single "lucky" photon that manages to bounce around hundreds of times before escaping.