Fig. 1. Structure of the proposed broadband athermal waveguide, which consists of a Si core, a TiO2 lower cladding, and a Si3N4 upper cladding.

Fig. 2. Effective TOC of the proposed broadband athermal waveguide, with a small variation of ±1×10−6/K in the waveband of 1400 to 1700 nm. The insets show the norm of the electric field, |E|, of the waveguide mode at different wavelengths, 1450, 1550, 1650, and 1750 nm, respectively.

Fig. 3. Shifts of effective TOC curves when the structural parameters are changed, with (a) varied W of ±10%, (b) varied H1 of ±50%, (c) varied H2 of ±5%, and (d) varied H3 of ±1%.

Fig. 4. (a) Optical loss of the proposed waveguide. It shows a low-loss performance in the bandwidth with a broadband athermal property. (b) Effective-TOC curves of the micro-ring resonators with different ring radii. (c) Bending loss with different radii. This shows a low-loss performance and a stable athermal property of the proposed broadband athermal micro-ring resonators.

Fig. 5. TDWS of the microring resonator with a radius of 30 μm using the proposed waveguide. The TDWS is ±0.5  pm/K in the wavelength range of 1400 to 1700 nm, corresponding to a wavelength shift of <15  pm with a temperature change of 30°C.