High‐Resolution On‐Chip Digitally Tunable Spectrometer Based on Double‐Cascaded Ring Resonators

Fast and accurate detection and analysis of light spectrum emerge as an important tool in several scientific fields and applications, hence demanding the design of precise, reliable, and fast instruments. In this article, an integrated spectrometer is presented based on two cascaded ring resonators covered with a phase change material. The Vernier architecture is implemented by these segments of phase change materials, allowing for a digital scan of wavelengths. Resolution smaller than 0.1 nm can be achieved, together with a footprint of ≈0.03 mm 2 and a bandwidth of the order of tens of nanometers.