A resonant photodetector assembly (10) which uses multiple reflections of light within a photodetector (20) to convert input light into an electrical signal. The photodetector (20) includes a combination of generally planar semiconductor layers including a photodetector active layer (36) where light is converted into an electrical output. The photodetector (20) further includes a first outer electrical contact layer (34) and a second outer electrical contact layer (42). A waveguide (22) is positioned on the photodetector (20) and has a waveguide active layer (26) positioned between a pair of waveguide cladding layers (24, 28), a first end (30) for receiving input light and a second end (50) for reflecting the light. A reflector (32) is positioned on the second end (50) of the waveguide (22) at an angle relative to a line parallel to the substrate (14), where the reflector (32) reflects the light received by the first end (30) of the waveguide active layer (26) towards the photodetector (20). A reflector (38) is positioned on the second outer layer (42) of the photodetector (20) and provides a reflective surface for reflecting the light within the photodetector (20).