Dual-Bandpass Filtering in Prism Pair Coupled Planar Optical Waveguide

A dual-bandpass filter (DBPF) based on prism pair coupled planar optical waveguide (POW) is theoretically designed. The POW is comprised of 5 layers of uniform dielectrics. Simulation results show two passbands respectively peaking at central wavelengths 1310nm and 1550nm. The peak transmittances of the two passbands keep over 99.9% with the material losses of the dielectrics considered. The designing method for DBPF with two arbitrary central wavelengths based on a similar structure is presented by analyzing the effect of each layer’s thickness on the filter’s transmittance spectrum. The analysis indicates that the wavelength interval, the mean central wavelength and the bandwidths of the two passbands are respectively controlled by adjusting the thicknesses of buffer, guiding and cladding layers of the symmetrically structured 5-layer POW. The proposed DBPF and its designing method may find applications in wireless communications and dual spectral detection.