In this work, waveguide integrated multiple quantum well p-i-n photodiodes are developed and characterized. Compared to bulk photodiodes, multiple quantum well photodiodes have special properties including a large and tunable polarization dependent loss. It makes multiple quantum well photodiodes a potential candidate for various applications, especially in polarization-diversity coherent optical receivers. Furthermore, multiple quantum well photodiodes are supposed to simplify monolithic integration of optoelectronic circuits.