An optical gyroscope (100, 200, 300, 400) comprising: • a passive closed-path optical cavity configured for receiving at least a first optical signal in such a way that the received first optical signal is associated with at least one clockwise cavity mode of the optical cavity or at least one counter-clockwise cavity mode of the optical cavity, • extraction means (112, 122) in optical communication with the optical cavity for extracting therefrom a fraction of the received first optical signal, characterized by said fraction of the received first optical signal depending on a carrier wavelength of the first optical signal according to a first spectral transmittance curve comprising a plurality of transmission peaks, and being increased when the carrier wavelength of the first optical signal approaches a resonance condition of the optical cavity in optical communication with said extraction means (112,122), corresponding to a transmission peak on the first spectral transmittance curve, • at least one readout channel for spectrally modifying an extracted fraction of the received first optical signal and for detecting optical power levels based on the modified extracted fraction, the at least one readout channel comprising • an interferometric device (123, 123a, 123b) having associated therewith at least one second spectral transmittance curve comprising a plurality of transmission peaks, the interferometric device being adapted for spectrally aligning at least one transmission peak on the at least one second spectral transmittance curve with a transmission peak on the first spectral transmittance curve, wherein a difference in free spectral ranges associated with said at least one second spectral transmittance curve and said first spectral transmittance curve is such that a spectral modification, determined by a spectral product obtained from said at least one second spectral transmittance curve and from said first spectral transmittance curve, produces a spectral Vernier effect in a wavelength region of interest, and wherein said difference between free spectral ranges is greater than any one of the spectral widths associated with the plurality of transmission peaks of said at least one second spectral transmittance curve and of said first spectral transmittance curve in said wavelength region of interest, and • at least one readout detector (124, 124a, 124b) optically coupled to an output of the interferometric device (123, 123a, 123b). • a passive closed-path optical cavity configured for receiving at least a first optical signal in such a way that the received first optical signal is associated with at least one clockwise cavity mode of the optical cavity or at least one counter-clockwise cavity mode of the optical cavity, • extraction means (112, 122) in optical communication with the optical cavity for extracting therefrom a fraction of the received first optical signal, • at least one readout channel for spectrally modifying an extracted fraction of the received first optical signal and for detecting optical power levels based on the modified extracted fraction, the at least one readout channel comprising • an interferometric device (123, 123a, 123b) having associated therewith at least one second spectral transmittance curve comprising a plurality of transmission peaks, the interferometric device being adapted for spectrally aligning at least one transmission peak on the at least one second spectral transmittance curve with a transmission peak on the first spectral transmittance curve, wherein a difference in free spectral ranges associated with said at least one second spectral transmittance curve and said first spectral transmittance curve is such that a spectral modification, determined by a spectral product obtained from said at least one second spectral transmittance curve and from said first spectral transmittance curve, produces a spectral Vernier effect in a wavelength region of interest, and wherein said difference between free spectral ranges is greater than any one of the spectral widths associated with the plurality of transmission peaks of said at least one second spectral transmittance curve and of said first spectral transmittance curve in said wavelength region of interest, and • at least one readout detector (124, 124a, 124b) optically coupled to an output of the interferometric device (123, 123a, 123b). • an interferometric device (123, 123a, 123b) having associated therewith at least one second spectral transmittance curve comprising a plurality of transmission peaks, the interferometric device being adapted for spectrally aligning at least one transmission peak on the at least one second spectral transmittance curve with a transmission peak on the first spectral transmittance curve, wherein a difference in free spectral ranges associated with said at least one second spectral transmittance curve and said first spectral transmittance curve is such that a spectral modification, determined by a spectral product obtained from said at least one second spectral transmittance curve and from said first spectral transmittance curve, produces a spectral Vernier effect in a wavelength region of interest, and wherein said difference between free spectral ranges is greater than any one of the spectral widths associated with the plurality of transmission peaks of said at least one second spectral transmittance curve and of said first spectral transmittance curve in said wavelength region of interest, and • at least one readout detector (124, 124a, 124b) optically coupled to an output of the interferometric device (123, 123a, 123b).