Athermal Silicon Photonics for Waveguide Systems

Athermal silicon photonics seeks to eliminate or greatly reduce the dependence of photonic device performance on temperature fluctuations by engineering waveguides and resonators so that net changes in refractive index with temperature are cancelled. Silicon’s high thermo-optic coefficient leads to drift in resonance wavelength or phase in microring resonators and interferometers, undermining stability in applications such as data-centre interconnects, optical sensing and coherent communications. Athermalisation is achieved through a combination of material selection, composite cladding, waveguide geometry and passive compensation structures. By balancing the positive thermo-optic shift of silicon with materials having a negative thermo-optic response or by tailoring mode confinement, devices can operate over a broad temperature range without active thermal control. This approach reduces power consumption, eases thermal management in dense photonic circuits and enhances reliability in real-world environments. Recent advances include integration of thin-film coatings and two-dimensional materials for passive trimming, novel cladding schemes compatible with CMOS fabrication and comprehensive analytical models for design optimisation. Together, these developments promise to deliver robust, energy-efficient photonic systems for next-generation telecommunications, sensing and high-performance computing.

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Athermal Silicon Photonics for Waveguide Systems publication trend

The graph below shows the total number of articles in athermal silicon photonics for waveguide systems across all publications each year (not limited to Nature Index journals).

Technical terms

Waveguide: A structure that confines and directs light by total internal reflection, typically a high-index core surrounded by lower-index cladding.

Thermo-optic effect: The change in refractive index of a material with temperature, quantified by the thermo-optic coefficient.

Athermalisation: The design principle of cancelling opposing thermo-optic contributions so that net device response is temperature independent.

Microring resonator: A circular waveguide that supports resonant modes, where small refractive-index changes shift the resonant wavelength.

Mach-Zehnder interferometer: An interferometric device splitting light into two paths and recombining it, sensitive to phase differences induced by temperature or index changes.

Cladding: The outer layer of a waveguide, whose material and thickness influence mode confinement and thermal response.

References

1. Simultaneous optical power insensitivity and non-volatile wavelength trimming using 2D In4/3P2Se6 integration in silicon photonics. npj 2D Materials and Applications (2024).
2. Athermal silicon microring resonators with titanium oxide cladding.. Optics Express (2013).
3. Athermal Silicon-on-insulator ring resonators by overlaying a polymer cladding on narrowed waveguides. Optics Express (2009).
4. An exact analysis of the temperature control of optical waveguides. Optical and Quantum Electronics (2025).