Methods and systems for an ASIC with a laser with the laser's back-facet illumination being monitored by a photodetector situated such that the substrate of the ASIC acts as a waveguide for the back-facet illumination between the laser and the photodetector (monitor). In an embodiment, the laser and monitor are situated on the same side of the ASIC and the back-facet illumination is reflected off the far end of the ASIC substrate before reaching the monitor.