Abstract: A novel eight-channel wavelength division multiplexer（WDM）based on the three-ring series resonator array was designed by using signal flow graph theory and microring resonance theory in this paper. The output spectrum of this device was simulated by MATLAB. By optimizing the coupling coefficient and the radius of the micro-ring resonator of the device，the output spectrums with the quality factor reached 1 687. 09，the fineness reached 13. 59，and the shape factor reached 0. 651 were obtained in this structure. We can construct a dense wavelength division multiplexer structure by using the multiple microrings array coupled bus waveguides. It was also the foundation for the design and manufacture of the multi-channel WDM device.

Key words: integrated optics, optical-fiber ring resonator, optical filter, dense wavelength division multiplexer