Tunable polarization beam splitter and broadband optical power sensor using hybrid microsphere resonators.

Abstract

Based on silica microsphere resonators embedded with iron oxide nanoparticles, we proposed and fabricated an all-optical and continuously tunable polarization beam splitter (PBS), and a broadband optical power sensor (OPS) with high sensitivity. The PBS is realized since the effective refractive indexes of the transverse-electric and transverse-magnetic polarization modes in the microsphere resonator are different. Due to the excellent photothermal effect of iron oxide nanoparticles, we realized the all-optical and continuously tunable PBS based on the hybrid microsphere resonator. A maximum polarization splitting ratio of 20 dB and a tuning range of 5 nm are achieved. Based on this mechanism, the hybrid microsphere resonator can also be used as a broadband OPS. The sensitivity of the OPS is 0.487 nm/mW, 0.477 nm/mW, and 0.398 nm/mW when the probe wavelength is 690 nm, 980 nm, and 1550 nm, respectively. With such good performances, the tunable PBS and the broadband OPS have great potential in applications such as optical routers, switches and filters.