Sub-nm resolution ultra-broadband photonic on-chip spectrometer

An ultra-broadband spectrometer with high resolution comprising of on-chip photonic components is proposed here. The spectrometer design consists of cascaded Mach Zehnder interferometers, tunable high-Q ring resonators, and arrayed waveguide grating wavelength filters. The multi-stage design filter showcases the spectrum retrieval process for a 100 nm wide unknown spectrum centered around 1550 nm input via a single optical input and filters over 8 optical output channels with 200 pm resolution. This makes the ratio of spectral bandwidth to resolution to be 500, which is among the highest figure of merit for such a broadband on-chip spectrometer.