Silicon-on-Insulator Spatial Heterodyne Spectrometer Chip for the Mid-Infrared

We demonstrate fur the- first time a silicon-on-insulator spatial heterodyne waveguide spectrometer chip operating in the mid-infrared. The device comprises a MMI splitting tree, followed by an array of 42 Mach-Zehnder interferometers with linearly increasing optical path differences. The fabricated device was characterized in the 3717–3772 nm wavelength range by retrieving the spectral line of a quantum cascade laser line, with a wavelength resolution of 2.8 nm.