A low-cost edge-illuminated refracting-facet photodiode module with large bandwidth and high responsivity

We have demonstrated a low-cost, high-speed and high-responsivity photodiod e module utilizing an edge-illuminated refracting-facet photodiode (RFPD), in which the incident light parallel to the up-side surface is refracted at an angled facet and absorbed in a thin absorption layer. Since the inciden t light refracted at an angled facet penetrates at a definite angle to the absorption layer, the absorption length is effectively longer, resulting in high responsivity, In addition, since the RFPD chip has a large tolerance to optical-axis misalignment, the module can be produced with a simple sing le-lens alignment configuration, which enables low-cost fabrication. The fa bricated RFPD module has a large-bandwidth (38 GHz) and high-responsivity ( 1 AW). The measured polarization dependence of responsivity is less than 0. 2 dB at a wavelength of 1.55 mu m.