Improvement of transmission characteristics of Fabry-Perot optical filter

Abstract

This report describes a study on a tunable Fabry-Perot optical-waveguide filter fabricated on LiNbO_3 substrate. We investigated the relation between the effective indices of the fundamental mode and the insertion loss when the absolute value of negative applied-voltage increased. With various waveguide widths, the effective indices of fundamental mode were calculated by the computer simulation. The simulation result says that the absolute value of negative voltage with the fundamental mode becoming cut-off increases as the waveguide is wider. The experimental result showed that the fluctuation of insertion loss was suppressed under 0.8 dB at 14um of the waveguide width.