Thermally-controlled transparency in multi-ring cascaded filters

We propose a novel control scheme to induce transparency through thermal tuning in multi-stage cascaded ring structures. Higher-order MicroRing Resonator structures are fundamental blocks for high Q-factor filtering as well as wavelength-sensitive applications. Through the proposed thermal control scheme, which does not require additional heating elements with respect to the traditional calibration and uncertainty-compensation setup, we can manage both the central wavelength of the add-drop filter, as well as toggle the transparent state. Through this technique the add-drop filter can be switched off, allowing the signal to pass through without frequency-dependent effects and just introducing flat-band crosstalk.