High Q low mode volume microsphere integrated Fabry–Perot cavity for optofluidic

We develop a hybrid optofluidic microcavity by placing a microsphere with a diameter ranging from 1 to 4 μm in liquid-filled plano-plano Fabry–Perot (FP) cavities, which can provide an extremely low effective mode volume down to 0.3–5.1 μm3 while maintaining a high Q-factor up to 1×104–5×104 and a f