The first broadband laser based on semiconductors has been developed by physicists in the US. In contrast to existing devices – which emit pulses of light – the laser emits a continuous beam of infrared radiation over a two-micrometre wavelength range. Claire Gmachl and colleagues at Bell Labs believe their laser – which they plan to modify to emit visible light – could be used for gas sensing, metrology and optical communications (C Gmachl et al 2002 Nature 415 883).