We propose and demonstrate an in-line channel power monitor (ICPM) based on helium ion implanted silicon waveguides. The implanted waveguide can detect light at below-bandgap wavelengths (1440-1590 nm) which are normally not detectable by silicon. We study the enhanced photoresponse of helium ion implanted samples which were annealed at 200°C, 300°C, or 350°C for different durations. Optical absorption and photodetector current measurements were performed for each sample. The ICPM can provide the same function as a waveguide tap coupler and a hybrid-integrated conventional photodiode.