Temperature-independent narrowband optical filterat 1.3 µm wavelength by an athermal waveguide

The authors report the realisation of a temperature independent narrowband optical filter at 1.3 µm wavelength. A ring resonator has been designed and fabricated using an athermal waveguide, in which the optical path length is independent of temperature. The temperature coefficient of the central wavelength was successfully reduced to 7 × 10-4 nm/K (7% of that of a conventional filter).