Monolithically Integrated 40-Wavelength Demultiplexer and Photodetector Array on Silicon

We demonstrated a 40-channel dense-wavelength-division-multiplexed (DWDM) monolithically integrated receiver on silicon, which consists of a silicon nitride
$(\hbox{Si}_{3}\hbox{N}_{4})$
arrayed waveguide grating (AWG) demultiplexer with integrated germanium-on-silicon waveguide photodetectors. Net responsivities from a cleaved standard single-mode fiber to detectors of
$0.15\sim 0.22$
A/W are measured, with flattened passbands with 1-dB bandwidth over 60% of the 200-GHz channel spacing. Single-channel operation up to 40 Gb/s is demonstrated with a SiGe transimpedance amplifier.