Athermal waveguides and resonators with three zero-thermal-drift wavelengths

In the rapidly evolving fields of silicon photonics, microresonator-based devices have promising applications due to a small footprint, high performance, and low power consumption. However, the frequency of the optical resonator could drift due to the change in the optothermal refractive index. Here, we propose two types of broadband athermal waveguides which are achieved through the mode anti-crossing effect. These waveguides have three zero-thermal-drift wavelengths (ZTDWs), while the previously published structures have no more than two ZTDWs. A polycarbonate (PC)-coated waveguide shows a small effective thermo-optical coefficient (TOC) variation of ±1.5×10-6 /K from 1350 to 1790 nm. For the TiO2-coated waveguide, the effective TOC has a variation of ±1.5×10-6 /K from 1510 to 2090 nm. The temperature depended wavelength shift (TDWS) of both microring resonators with a radius of 100 μm has a variation of ±1 pm/K. Both athermal microring resonators show a low bending loss and stable broadband athermal property at longer wavelengths. The highly stable broadband athermal performance of microring resonators will greatly expand the applications in optical communications and sensing systems.