Spectrometer for analyzing the spectrum of a Brillouin scattered light, comprising: input means for receiving the scattered light; selecting means coupled to the input means for selecting and separating specific multiple frequency components of the scattered light, wherein said selecting means comprise at least one main input; and at least an optical detector coupled to the selecting means for measuring the intensity of the different frequency components and reconstructing the spectrum profile of the scattered light, wherein the selecting means are composed by an optical integrated circuit having at least an input port, at least an output port and at least a pass port, said circuit comprising at least one selecting optical ring resonator having an input waveguide for receiving the light, a closed loop waveguide having an effective refractive index n eff and coupled to the input waveguide for selecting at least a specific frequency ν res of the scattered light, an output waveguide coupled to the closed loop waveguide for the output of the selected frequencies and a pass waveguide coupled to the input waveguide and to the closed loop waveguide for the output of the not selected frequencies and wherein the selecting means further comprise at least a modulator element coupled to the closed loop waveguide of the selecting optical ring resonator for modulating the effective refractive index n eff and scanning the different multiple frequency components through the variation of the optical path of the closed loop waveguide, characterized in that the selecting means comprise a plurality of selecting optical ring resonators (32 1,... 32 N) arranged in cascade, wherein the closed loop waveguide (34 1) of a first optical ring resonator (32 1) is coupled with the closed loop waveguide (34 2) of a second successive optical ring resonator (32 2) and wherein between the closed loop waveguide (34 1) of the first optical ring resonator (32 1) and the closed loop waveguide (34 2) of the second successive optical ring resonator (32 2) are located detuning means, and wherein the selecting means comprise at least a suppressing optical ring resonator for suppressing or attenuating the elastic components of the scattered light, wherein said suppressing optical ring resonator is positioned between the input port of the optical integrated circuit and the selecting optical ring resonator, wherein the suppressing optical ring resonator comprises a pass waveguide coupled to the input waveguide of the selecting optical ring resonator. input means for receiving the scattered light; selecting means coupled to the input means for selecting and separating specific multiple frequency components of the scattered light, wherein said selecting means comprise at least one main input; and at least an optical detector coupled to the selecting means for measuring the intensity of the different frequency components and reconstructing the spectrum profile of the scattered light, wherein the selecting means are composed by an optical integrated circuit having at least an input port, at least an output port and at least a pass port, said circuit comprising at least one selecting optical ring resonator having an input waveguide for receiving the light, a closed loop waveguide having an effective refractive index n eff and coupled to the input waveguide for selecting at least a specific frequency ν res of the scattered light, an output waveguide coupled to the closed loop waveguide for the output of the selected frequencies and a pass waveguide coupled to the input waveguide and to the closed loop waveguide for the output of the not selected frequencies and wherein the selecting means further comprise at least a modulator element coupled to the closed loop waveguide of the selecting optical ring resonator for modulating the effective refractive index n eff and scanning the different multiple frequency components through the variation of the optical path of the closed loop waveguide, characterized in that the selecting means comprise a plurality of selecting optical ring resonators (32 1,... 32 N) arranged in cascade, wherein the closed loop waveguide (34 1) of a first optical ring resonator (32 1) is coupled with the closed loop waveguide (34 2) of a second successive optical ring resonator (32 2) and wherein between the closed loop waveguide (34 1) of the first optical ring resonator (32 1) and the closed loop waveguide (34 2) of the second successive optical ring resonator (32 2) are located detuning means, and wherein the selecting means comprise at least a suppressing optical ring resonator for suppressing or attenuating the elastic components of the scattered light, wherein said suppressing optical ring resonator is positioned between the input port of the optical integrated circuit and the selecting optical ring resonator, wherein the suppressing optical ring resonator comprises a pass waveguide coupled to the input waveguide of the selecting optical ring resonator.