Aerospace Instrument-Making Annotation << Back Optical Sensors Based on Diffraction Bragg Gratings Parfyonov N.M., Chemodanov V.B., Klimov I.S. A fi ber Bragg grating is a distributed Bragg refl ector (a type of diffraction grating) formed in the core of an optical fi ber with a narrow refl ection spectrum. The phenomenon of diffraction is associated with the propagation of radiation in a medium with inhomogeneities that violate the geometric laws of optics. The spectral selectivity of refl ection from fi ber Bragg gratings is due to the periodic change along the length of the refractive index of the core and the diffraction of the beam by these periodic optical inhomogeneities. The spatial period of inhomogeneities is selected in such a way that light waves with the required wavelength are refl ected in it. A large number of lines with a small change in the refractive index leads to a very narrow refl ection spectrum - the width of the refl ection spectrum is usually a fraction of a nanometer. The period of the structure and, accordingly, the wavelength of refl ected light changes when the fi ber is mechanically compressed or stretched. This phenomenon is used in fi ber optic sensors, for example, in strain gauge measurements and for tuning laser wavelengths within narrow limits. A change in temperature leads to a thermal change in the length of the structure and also shifts the refl ection spectrum. Keywords: optical sensor, diffraction Bragg grating, refl ection spectra. DOI: 10.25791/aviakosmos.12.2023.1381 Pp. 48-55.