Tunable Polarized Microcavity Characterized by Magnetic Circular Dichroism Spectrum

Area of Science:

• Photonics and Materials Science
• Investigating novel magneto-optical phenomena in engineered microcavities.

Background:

• Tunable resonators are crucial for applications like color filtering and optical sensing.
• Existing methods for dynamic resonator tuning are limited, hindering broader applications.
• Controlling polarization characteristics is key to expanding resonator functionalities.

Purpose of the Study:

• To demonstrate a magnetically regulated circular polarized resonant microcavity.
• To achieve dynamic tuning of resonant frequency and polarization performance.
• To explore the potential for on-chip magneto-optical devices.

Main Methods:

• Fabrication of an ultrathin ferrimagnetic composite metal layer (Ta/CoTb).
• Utilizing the magnetic properties of the Ta/CoTb layer to tune the microcavity.
• Characterization of resonant frequency shifts and polarization changes under magnetic fields.

Main Results:

• Successful dynamic tuning of the microcavity's resonant frequency and polarization.
• Observation of a significant magnetic circular dichroism (MCD) signal (∼3.41%).
• A microcavity valley position shift of 5.41 nm with a small applied magnetic field.
• The microcavity exhibits two-stable states at 0 T due to magnetic remanence.
• Switching between states achieved with a minimal magnetic field (∼0.01 T).

Conclusions:

• The demonstrated magnetically tunable microcavity offers dynamic control over optical properties.
• The use of ferrimagnetic films enables efficient magneto-optical modulation.
• This technology holds promise for developing advanced on-chip magneto-optical devices.