Fourier Transform Microspectrometer with Interleaved Arrayed Waveguide Gratings

We propose a new type of arrayed waveguide grating (AWG) device that operates as a Fourier transform (FT) spectrometer without the need of scanning elements. The large input aperture size typical of a FT spectrometer eliminates the requirement for a narrow single mode input waveguide while still achieving a high spectral resolution. By replacing a single mode input waveguide by a wide ridge or slab waveguide, the light gathering capability (étendue) is markedly increased. An example of the device with a resolution of 0.07 nm (~ 10 GHz) and designed for the silicon-on-insulator (SOI) platform is presented. The spectra calculated from the simulated interferograms show no noticeable deterioration for aperture widths as large as 40 µm, yielding more than 50 fold increase in aperture size compared to a conventional AWG or an echelle grating based device at the equivalent resolution.