We consider device design, fabrication, and operation of integrated optical photodiode arrays in which p-i-n junction photodiodes are formed in silicon. A SiO(2) layer on silicon serves as the effective substrate for a KPR waveguide. Light is coupled from the waveguide at the detector region either through the evanescent field or by multiple refraction into the detector. The waveguide-photodiode structure is designed so that nearly 100% of the incident optical energy can be absorbed in the photodiode junction depletion region. A device quantum efficiency of 80% is measured compared to a theoretical value of 93%.