Ultrahigh-resolution on-chip spectrometer with silicon photonic resonators

A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution. It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators for achieving a broadened working window. The present on-chip spectrometer has a footprint as compact as 0.35 mm2, and is realized with standard multi-project-wafer foundry processes. The measurement results show that the on-chip spectrometer has an ultra-high resolution ∆λ of 5 pm and a wide working window of 10 nm. The dynamic range defined as the ratio of the working window and the wavelength resolution is as large as 1940, which is the largest for on-chip dispersive spectrometers to the best of our knowledge. The present high-performance on-chip spectrometer has great potential for high-resolution spectrum measurement in the applications of gas sensing, food monitoring, health analysis, etc.