A planar slab-waveguide photodiode with a pseudowindow region in front of the waveguide

A planar waveguide photodiode having a selectively diffused p-n-junction with a simple pseudowindow region has been developed for access network applications. By forming the p-n-junction away from the input facet of the diode, the input facet is kept in neutral under the reverse-bias condition. We expect the facet degradation to be significantly suppressed in this structure. An extremely low dark current of less than 3 pA and sufficient bandwidth of over 4 GHz were confirmed.