Sidewall photodetectors for integrated photonic devices and their method of manufacture. An embodiment includes a p-i-n film stack formed on a sidewall of a substrate semiconductor feature having sufficiently large area to accommodate the spot size of a multi-mode fiber. An embodiment includes a first sidewall photodetector coupled to a second sidewall photodetector by a waveguide, the first sidewall photodetector having an i-layer tuned to absorb a first wavelength of light incident to the first sidewall and pass a second wavelength of light to the second sidewall photodetector having an i-layer tuned to absorb the second wavelength.