Erbium-doped and Raman microlasers on a silicon chip fabricated by the sol-gel process

We report high-Q sol-gel microresonators on silicon chips, fabricated directly from a sol-gel layer deposited onto a silicon substrate. Quality factors as high as 2.5× 107 at 1561 nm were obtained in toroidal microcavities formed of silica sol-gel, which allowed Raman lasing at absorbed pump powers below 1 mW. Additionally, Er3+ -doped microlasers were fabricated from Er3+ -doped sol-gel layers with control of the laser dynamics possible by varying the erbium concentration of the starting sol-gel material. Continuous lasing with a threshold of 660 nW for erbium-doped microlaser was also obtained.