On-chip broadband high-resolution digital Fourier-transform spectrometer

We present a foundry-processed and fully-packaged chip-scale digital Fourier-transform spectrometer. The device consists of a tunable Mach-Zehnder Interferometer, where the optical path length difference is tuned in discrete steps using optical switches. We employ 10 optical switches to generate 1024 unique optical path length differences, allowing for operation of the spectrometer covering O/S/C/L/U telecom bands (380 nm bandwidth) with 0.02 nm resolution. We further demonstrate a novel integrated notch filtering function capable of selective laser line removal, enabling improved signal-to-noise ratio in laser-pumped spectroscopy.