59-nm trimming of center wavelength of ARROW-type vertical coupler filter by UV irradiation

An antiresonant reflecting optical waveguide (ARROW)-type vertical coupler filter (VCF) with a polysilane cover layer is designed and fabricated to demonstrate the trimming of the center wavelength of the filter by ultraviolet (UV) irradiation. The propagation constant of the upper waveguide of the VCF was modified by UV irradiation on the polysilane cover in the presence of oxygen. The refractive index of polysilane can be adjusted from 1.448 to 1.427 by the exposure time of the UV irradiation. A wide trimming range of 59 nm (1567.5 nm to 1508.8 nm) of center wavelength is demonstrated.