Integrated Broadband Mid-Infrared Polarization Insensitive Fourier-Transform Spectrometer

Due to the rotational and vibrational frequency, molecules show unique absorption spectrum in the mid-infrared fingerprint region from 500 to 1500 cm(-1). Hence, the demonstration of integrated on-chip spectrometers with compact sizes, cost-effective and high performance is important. Here, we demonstrate the first polarization insensitive broadband operational mid infrared spatial heterodyne Fourier-Transform spectrometer (SHFTS) working beyond 5 mu m wavelength. A resolution better than 15cm(-1) for both TE/TM polarizations has been experimentally demonstrated in an unprecedented bandwidth of 800 cm(-1) (from 5 mu m to 8.5 mu m wavelength) for our integrated on-chip SHFTS, using a graded-index Ge-rich SiGe photonics platform.