We report the design criteria and performance of Si ring resonators for passive athermal applications in wavelength division multiplexing (WDM). The waveguide design rules address i) positivenegative thermo-optic (TO) composite structures, ii) resonant wavelength dependent geometry to achieve constant confinement factor (Γ) and iii) observation of small residual second order effects. We develop exact design requirements for a temperature dependent resonant wavelength shift (TDWS) of 0 pm/K and present prototype TDWS performance of 0.5pm/K. We evaluate the materials selection tradeoffs between high-index contrast (HIC) and low-index contrast (LIC) systems and show, remarkably, that FSR and footprint become comparable under the constraint of athermal design.

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Persistent URL dx.doi.org/10.1364/OE.18.017631
Journal Optics Express
Raghunathan, V. (Vivek), Ye, W.N, Hu, J. (Juejun), Izuhara, T. (Tomoyuki), Michel, J. (Jurgen), & Kimerling, L. (Lionel). (2010). Athermal operation of Silicon waveguides: Spectral, second order and footprint dependencies. Optics Express, 18(17), 17631–17639. doi:10.1364/OE.18.017631