A bidirectional optoelectronic device comprises a photodetector and a light source on a waveguide substrate, and a drive circuit for the light source. The waveguide substrate can include light collector(s) or trap(s) for redirecting and attenuating portions of optical signals propagating in waveguide layers on the substrate but not guided by a waveguide. A protective encapsulant can be applied that includes hollow dielectric microspheres to reduce electrical cross-talk, and that can further include an optical absorber to reduce optical cross-talk.