The light used in optical fibres is produced by a laser. The problem is to control the wavelength. If the wavelength drifts from its set value, perhaps through changes in temperature, the signal may not be fully received at the other end of the fibre. Until now, this has required several different devices, but the FUNFOX team has created a single, integrated chip including the laser itself and a monitor that measures the wavelength and ensures that it remains stable, no matter what the environmental conditions.