Investigation of Q degradation in low-loss Si3N4 from heterogeneous laser integration

Qs above 108 have been demonstrated in CMOS-foundry-fabricated microresonators, but preserving the low loss during heterogeneous integration of III-V lasers has proven difficult. Here, Si3N4 resonator Qs are measured between laser backend processing steps, showing loss increases from certain steps and low-loss restoration after annealing.