Application of Resonant-Cavity 4x4 Arrayed Photodetector for SDM-WDM-FSO Beam Detection

We propose a new approach of direct detection of SDM–WDM–FSO beams using the newly developed resonant cavity (RC) 4 × 4 photodetector (PD) array device, which integrates functions in such as an array waveguide grating (AWG), multi-parallel photoreceivers, and mitigating optical alignment tolerance in the conventional WDM–FSO system into one chip. The RC-PD array device worked for not only wavelength separation in WDM beams, but also direct detection of spatial parallel beam using the expanded aperture size in a 4 × 4 array structure. Reception of 2-WDM 2-parallel, and 1-λ 4-parallel beams at 25 Gbps through multi-core fiber was successfully demonstrated at a distance of 1.5 m to confirm the device concept.