A light-emitting device including a light-emitting diode including an n-doped InGaN layer and a p-doped GaN layer, and an active zone including a number m of InGaN-emitting layers each one arranged between two InGaN barrier layers, of which the indium compositions of the emitting layers are different and are greater on the side of the n-doped InGaN layer than on the side of the p-doped GaN layer, and of which the indium compositions of the barrier layers are different and which are greater on the side of the n-doped InGaN layer than on the side of the p-doped GaN layer. An electric power supply supplies the diode with a periodic signal. A controller of the power supply can alter the peak value of the periodic signal according to a spectrum of the light emitted.