Ultra-compact silicon rings with high thermal tuning efficiency demonstrated as an 8×400 GHz WDM filter

This paper has achieved a new benchmark, $4.34 \mathrm{~mW} / \pi$, in minimizing the thermal tuning power for silicon rings with FSR $\geq 3.2 \mathrm{THz}$. Moreover, an $8 \times 400 \mathrm{GHz}$ WDM filter is demonstrated with channel isolation $\geq 33.1 \mathrm{~dB}$.