Optical narrow band filter without resonance's

Abstract

This paper introduces an optical wave filter, which uses gratings at 45? or 135? inclined grating lines that avoid any resonance's. Therefore, many more options to form the filter shape exist. In general, the filter design can be traced to that of transversal filters (finite impulse response filter, FIR filter). Such an integrated optical wave filter is characterized by steep filter slopes and a narrow pass band (less then 01nm) combined with a high stop band attenuation (more than 40dB) and a linear phase response in the pass band. Compared to conventional Bragg grating filters, the inclined grating line filters can have a flatter pass band and steeper filter skirts related to the width of the pass band. In general, the filter's realization is possible using any optical material. In view of the excellent optical properties the semiconductor material system InP/InGaAsP is used for manufacturing the filter.