Patent ID: 8546899

Claim:
A light receiving element comprising: a waveguide that includes a waveguide core; a multi-mode interference waveguide that has a width larger than a width of the waveguide, the multi-mode interference waveguide being configured to receive a first light from the waveguide core at a first end; and a photodetection portion that includes a first semiconductor layer and an absorption layer disposed on the first semiconductor layer, the first semiconductor layer including at least one layer and being configured to receive a second light from the multi-mode interference waveguide at a second end, the absorption layer being disposed above the first semiconductor layer and being configured to absorb the second light, wherein a distance from the first end of the multi-mode interference waveguide to the second end of the photodetection portion is longer than (N−0.3) ×100% of a first length and shorter than N ×100% of the first length, the first length being the shortest length where self-imaging occurs in the multi-mode interference waveguide, N being a natural number, wherein a width of a bottom surface of the first semiconductor layer in the photodetection portion is larger than a width of the multi-mode interference waveguide and a width of the absorption layer.