A random fiber laser is a thin glass thread through which light travels, but instead of reflecting off mirrors, it reflects off the tiniest irregularities in the fiber itself. Such a laser doesn't produce a steady beam: its light flickers and flares like a candle flame in a draft. In a new study, physicists for the first time traced in detail how this light flickers and discovered that its statistics are far richer than those of ordinary lasers.
It turned out that the light flashes in a random laser follow exactly this kind of heavy-tailed statistics: most readings are small, but occasionally there are giant spikes. Moreover, the scientists found a way to switch the laser's operating mode, from nearly steady glow to sharp random flashes, by changing the pump power. This paves the way for creating light sources with a predetermined character of randomness: for secure communications, sensing, or simulating complex natural processes.
The result connects two distant fields: the physics of disordered media and the statistical physics of complex systems. The random fiber laser becomes a small laboratory where one can study how order emerges from chaos, and vice versa.
A random fiber laser works without mirrors, which in a regular laser set the direction and purity of the beam. Its 'mirror' is millions of microscopic irregularities in the glass itself.