Abstract:The change of the transmission peaks of multi-cavity thin film interleaver in C-Band as the incident angle gradually increases is studied by means of eigen matrix.The results show:As the incident angle gradually increases,the central wavelengths of transmission peaks gradually move to the short-wavelength direction and the shapes of transmission peaks change periodically;as the incidence angle increasing,the number of transmission peaks decreases,the shapes of transmission peaks broaden,the transmission peaks′ central wavelengths and shapes change more quickly,and so when the incident angle has a very small change,the central wavelengths and the shapes of the transmission peaks change greatly.