Monolithic InGaAs photodiode array illuminated through an integrated waveguide

A linear array of InGaAs PIN photodiodes has been fabricated which can be illuminated through a slab waveguide from the opposite side of the InP substrate via total reflection at a V-groove mirror. Absorption losses in the double-heterostructure waveguide are 2.5 dB/cm. The internal quantum efficiency of the photodiodes, including the mirror loss, is 87%, and an optical crosstalk between the diodes better than ¿40 dB was measured.