Temperature-indepoendent narrow-band optical filter by an athermal waveguide

The temperature dependence of the central wavelength of narrow-band filters is a serious problem for the dense WDM systems. In this study, we realized a temperature independent narrow-band filter at 1.3μm wavelength. First, we designed an athermal waveguide in which optical path length is independent of temperature by using a finite element method. Using this athermal waveguide, we designed and fabricated a ring resonator. As a result, we successfully decreased the temperature coefficient of central wavelength to 7 × 10＾-4 nm/K, which is 7% of conventional SiC_2 waveguide filters and 0.7% of conventional semiconductor waveguide filters