Nonreciprocal microresonators for the miniaturization of optical waveguide isolators

Area of Science:

• Photonics and optical engineering.
• Applied physics and materials science.

Background:

• Miniaturization of optical components is crucial for integrated photonic circuits.
• Existing optical isolators and circulators often face limitations in size and performance.

Purpose of the Study:

• To propose and demonstrate novel designs for miniaturized optical waveguide isolators and circulators.
• To explore the use of nonreciprocal phase shifts in microresonators for device miniaturization.

Main Methods:

• Introducing nonreciprocal phase shifts into microresonator structures.
• Numerical demonstration of magneto-optical device operation.
• Analysis of single- and multi-resonator structures for bandwidth expansion.
• Investigation of three-dimensional resonators with finite heights.

Main Results:

• Achieved device miniaturization down to several tens of micrometers.
• Demonstrated nonreciprocal function through nonreciprocal resonance shifts.
• Showcased bandwidth expansion by increasing resonator count (filter order).
• Provided design guidelines for nonreciprocal optical circuits using practical resonators.

Conclusions:

• The proposed microresonator designs offer a viable path towards highly miniaturized optical isolators and circulators.
• The magneto-optical approach enables compact and potentially broadband nonreciprocal optical devices.
• The findings provide practical design considerations for future nonreciprocal optical integrated circuits.