 One issue with using silicon for an optical device is that silicon is a poor light emitter and cannot be used to make an electrically pumped laser.This means that lasers have first to be fabricated on a separate III-V semiconductor wafer before being individually aligned to each silicon device, in a process that is both costly and time-consuming, limiting the total number of lasers that can be used on a silicon photonic circuit.By using this wafer bonding technique many hybrid silicon lasers can be fabricated simultaneously on a silicon wafer, all aligned to the silicon photonic devices.