According to some possible implementations, an optical device may include a plurality of photodiodes, wherein alignment of the plurality of photodiodes with a fixed separation to a plurality of multi-mode waveguides disposed on an optical waveguide chip and with the same fixed separation is optimized by alignment of at least one of the plurality of photodiodes to at least one single-mode waveguide and translation of the optical waveguide chip relative to the plurality of photodiodes by a fixed offset of the at least one single-mode waveguide relative to the plurality of multi-mode waveguides.