A study on the whispering-gallery-mode lasers in Er3+-doped silica glass microspheres and its integrated with SOI slotted photonic crystal waveguides

In this work we review in part of the whispering-gallery-mode (WGM) lasers in Er
³⁺
-doped silica glass microspheres (μS) towards integration in silicon-on-insulator (SOI) slotted photonic crystal waveguides. The Er
³⁺
-doped silica glass μS with suitable diameters fabricated by using an electrical discharge method. The single-mode optical tapered fibers were used to guide the pumped laser into the μS surface and collect the resulting lasing emission. The observation of WGM at telecom regime is quantified. With the presented scheme, the selective single- or multi-emitted modes of the μS laser can be obtained by adjusting the coupling gap between the collection tapered fiber and the μS surface. To overcome the collection tapered fiber’s vibration at close range of the coupling gap, the guiding and coupling losses, while being compact enough to fit with complementary metal oxide semiconductor (CMOS) device, the integration of μS with SOI slotted photonic crystal waveguides is proposed and modeled with the help of finite-difference time-domain (FDTD) simulations. The designed structures may find application for the promising photonic devices such as the ultrahigh sensitivity sensors, the lasing sources, and towards advanced quantum communications.