A new class of optical resonators

Resonators are important components used in various fields of Optics. Our research introduces a new type of optical resonator that has unique characteristics compared to traditional ones like Fabry-Perot cavities. We invented a new process called "cascaded-mode conversion" that can produce supermodes in the resonator. This means that one mode transforms into another mode at each reflection. This new type of resonator has different properties that are determined not only by the length and refractive index of the medium, but also by the number of coupled modes and their reflection phases. This allows us to change the free spectral range, resonance linewidth, and quality factor, which were previously limited by design trade-offs. Additionally, cascaded-mode resonators can produce mode-independent resonances, which means that different spatial profiles of light can be manipulated using only one resonator. To prove our concept, we created several cascaded-mode resonators in a silicon-on-insulator integrated optics setup that operate at telecommunication wavelengths. We conducted experiments and simulations that showed the existence of cascaded-mode resonances and their unique spectral signatures.

See the article in Nature Communications here and the news article from Harvard SEAS here.