A new narrow-band filtering method based on the theory of multi-layer thin-film optical interference is proposed. A multi-layer interference filter is integrated within a waveguide channel completely in this scheme

so it is actually a part of the waveguide. Two different structures of waveguide interference filters are investigated and the output spectrum of a two-cavity structure with 27 periodic layers and the field distributions of a single-cavity structure are calculated. Finally

by changing the materials and structure

the influence of refractive index

thickness of waveguide thin-film layer and incident angle on peak transmittance

peak width at half-maximum

extinction ratio and effective area are analyzed. and the direction for further development is given too.