Light-emitting device comprising at least: - a light-emitting diode comprising at least one n-doped In Xn Ga (1-Xn) N layer and a p-doped GaN layer forming together a p-n junction, and an active zone arranged between the n-doped In Xn Ga (1-Xn) N layer and the p-doped GaN layer and comprising a number m of In Yi Ga (1-Yi) N-emitting layers (112, 112.1 - 112.3) each one arranged between two In Zj Ga (1-Zj) N barrier layers (114, 114.1 - 114.4) that are in contact with said emitting layer (112, 112.1 - 112.3) on the two opposite faces of said emitting layer (112, 112.1 - 112.3), wherein: • for i between 1 and m-1, the indium compositions of the emitting layers (112, 112.1 - 112.3) are such that Y(i+1) < Yi, the (i+1) th emitting layer (112, 112.1 - 112.3) being arranged between the (i) th emitting layer (112, 112.1 - 112.3) and the p-doped GaN layer; • for j between 1 and m, the indium compositions of the barrier layers (114, 114.1 - 114.4) are such that Z(j+1) < Zj, the (j+1) th barrier layer (114, 114.1 - 114.4) being arranged between the (j) th barrier layer (114, 114.1 - 114.4) and the p-doped GaN layer; • for i = j, the indium compositions of the emitting layers (112, 112.1 - 112.3) and of the barrier layers (114, 114.1 - 114.4) are such that Zj < Yi and Z(j+1) < Yi; with m: integer greater than or equal to 2; i: integer between 1 and m; j: integer between 1 and (m+1); - an electric power supply able to electrically power the light-emitting diode with a periodic signal, - a device for controlling the electric power supply which can alter the peak value of the periodic signal according to at least one spectrum of the light intended to be emitted by the light-emitting diode, and wherein the indium compositions Yi and/or Zj are such that: for i = j: 0.15 Yi < Zj < 0.9 Yi, and/or for j between 1 and m: 0.25 Zj < Z(j+1) < 0.9 Zj. - a light-emitting diode comprising at least one n-doped In Xn Ga (1-Xn) N layer and a p-doped GaN layer forming together a p-n junction, and an active zone arranged between the n-doped In Xn Ga (1-Xn) N layer and the p-doped GaN layer and comprising a number m of In Yi Ga (1-Yi) N-emitting layers (112, 112.1 - 112.3) each one arranged between two In Zj Ga (1-Zj) N barrier layers (114, 114.1 - 114.4) that are in contact with said emitting layer (112, 112.1 - 112.3) on the two opposite faces of said emitting layer (112, 112.1 - 112.3), wherein: • for i between 1 and m-1, the indium compositions of the emitting layers (112, 112.1 - 112.3) are such that Y(i+1) < Yi, the (i+1) th emitting layer (112, 112.1 - 112.3) being arranged between the (i) th emitting layer (112, 112.1 - 112.3) and the p-doped GaN layer; • for j between 1 and m, the indium compositions of the barrier layers (114, 114.1 - 114.4) are such that Z(j+1) < Zj, the (j+1) th barrier layer (114, 114.1 - 114.4) being arranged between the (j) th barrier layer (114, 114.1 - 114.4) and the p-doped GaN layer; • for i = j, the indium compositions of the emitting layers (112, 112.1 - 112.3) and of the barrier layers (114, 114.1 - 114.4) are such that Zj < Yi and Z(j+1) < Yi; with m: integer greater than or equal to 2; i: integer between 1 and m; j: integer between 1 and (m+1); • for i between 1 and m-1, the indium compositions of the emitting layers (112, 112.1 - 112.3) are such that Y(i+1) < Yi, the (i+1) th emitting layer (112, 112.1 - 112.3) being arranged between the (i) th emitting layer (112, 112.1 - 112.3) and the p-doped GaN layer; • for j between 1 and m, the indium compositions of the barrier layers (114, 114.1 - 114.4) are such that Z(j+1) < Zj, the (j+1) th barrier layer (114, 114.1 - 114.4) being arranged between the (j) th barrier layer (114, 114.1 - 114.4) and the p-doped GaN layer; • for i = j, the indium compositions of the emitting layers (112, 112.1 - 112.3) and of the barrier layers (114, 114.1 - 114.4) are such that Zj < Yi and Z(j+1) < Yi; with m: integer greater than or equal to 2; i: integer between 1 and m; j: integer between 1 and (m+1); with m: integer greater than or equal to 2; i: integer between 1 and m; j: integer between 1 and (m+1); - an electric power supply able to electrically power the light-emitting diode with a periodic signal, - a device for controlling the electric power supply which can alter the peak value of the periodic signal according to at least one spectrum of the light intended to be emitted by the light-emitting diode, and wherein the indium compositions Yi and/or Zj are such that: for i = j: 0.15 Yi < Zj < 0.9 Yi, and/or for j between 1 and m: 0.25 Zj < Z(j+1) < 0.9 Zj. for i = j: 0.15 Yi < Zj < 0.9 Yi, and/or for j between 1 and m: 0.25 Zj < Z(j+1) < 0.9 Zj.