The Watts group at MIT has done some fantastic work into rare-earth doped silicon waveguides to produce lasers on a silicon platform [0]. However, I believe this work is still very much in the research stage. I'm not convinced their method is scalable to production for this $10 & million-unit-per-year LIDAR application since Erbium-doped waveguide lasers still require an off-chip pump laser source.

[0] (PDF): http://www.rle.mit.edu/pmg/documents/OpticsExpress2014Bradle...