Influence of Parametric Uncertainties on Narrow Width Bandpass Optical Filter of Prism Pair Coupled Planar Optical Waveguide

Bandpass optical filters with nano/sub nanometer bandwidth could be formed by prism pair coupled multi-mode planar optical waveguide. Its performance depends mainly on the parametric precision of the selected constituent materials, whose parametric uncertainties, such as material loss, layer thickness, and refractive index inaccuracy, could deteriorate the expected performance of a practical device. Theoretical simulations show that material loss is the dominant factor that affects the transmission efficiency, and the influence is dependent on the order of the guided modes. For the proposed filter configuration, at the highest loss level (10
^-4
) considered, the peak transmittance of the pass-band for the highest order (3
^rd
) guided mode keeps over 95%, whereas that of the lowest order (0
^th
) decreases to only 24%. Influence of the fabrication inaccuracy in refractive index is relatively more evident than that of the layer thickness, even though they both play the minor parts.