Photo-spectrometer based on the integration of InP/InGaAs photodetectors onto a Silicon-on- insulator etched diffraction grating

─We present the design and simulation results of an integrated wavelength demultiplexer. The device’s major components, which include the Silicon-on-insulator (SOI) etched diffraction grating and waveguide integrated InP/InGaAs MSM photodetectors are discussed in detail. The Silicon-on-insulator diffraction grating is fabricated using standard CMOS processes. The photodetectors are integrated on top of the SOI waveguide circuitry using benzocyclobutene (BCB) as a bonding agent. This integration can be done using wafer scale processing technologies, which is important to increase reliability and decrease cost. The photo-spectrometer-on-a-chip can be used as an optical channel monitor in modern wavelength division multiplexing (WDM) telecommunications networks: it provides real-time information on system performance at the optical layer. Another application is liquid or gas sample identification based on infrared spectroscopy. Keywords─Photo-spectrometer, etched diffraction grating, MSM photodetector