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

Area of Science:

• Photonics and Nanomaterials Science.

Background:

• Optical polarization beam splitters (PBS) and optical power sensors (OPS) are crucial components in photonics.
• Developing tunable and highly sensitive devices remains an active area of research.

Purpose of the Study:

• To propose and fabricate an all-optical, continuously tunable PBS and a broadband OPS.
• To leverage the unique properties of iron oxide nanoparticles in silica microsphere resonators.

Main Methods:

• Fabrication of hybrid silica microsphere resonators embedded with iron oxide nanoparticles.
• Utilizing the difference in effective refractive indexes for transverse-electric and transverse-magnetic modes.
• Exploiting the photothermal effect of iron oxide nanoparticles for tunability.

Main Results:

• Achieved a maximum polarization splitting ratio of 20 dB for the PBS.
• Demonstrated a continuous tuning range of 5 nm for the PBS.
• The hybrid microsphere resonator functioned as a broadband OPS with high sensitivity (e.g., 0.487 nm/mW at 690 nm).

Conclusions:

• The developed hybrid microsphere resonator enables an all-optical and continuously tunable PBS.
• The device also serves as a high-sensitivity broadband OPS.
• These tunable PBS and broadband OPS show significant potential for applications in optical routers, switches, and filters.