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

Microresonators have been extensively studied in integrated photonics over the past two decades. However, the thermal frequency drift of a resonator limits its applications in practice. Athermal microresonators, as a passive solution, have become highly attractive. We propose two types of broadband athermal waveguides, with three zero-thermal-drift wavelengths achieved through mode anti-crossing effect, for the first time. For the polymer-coated waveguide, the effective thermo-optical coefficient (TOC) has a 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. Over such a wide band of 440 or 580 nm, both the athermal microring resonators show excellent athermal property of <1 pm/K. The broadband athermal characteristics of the resonators would enable a wide variety of applications, e.g., wavelength-division multiplexing filters, modulators, lasers, sensors, and nonlinear optical sources.