Topology optimization of multi-track ring resonators and 2D microcavities for nonlinear frequency conversion

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nonlinear Optics

Background:

• Nonlinear optical processes are crucial for frequency conversion.
• Existing resonators often face limitations in efficiency and bandwidth.
• Integrated photonic devices require compact and high-performance components.

Purpose of the Study:

• To design wavelength-scale resonators using topology optimization.
• To enhance nonlinear frequency conversion processes (χ(2) and χ(3)).
• To achieve high quality factors (Q), small modal volumes (V), and large nonlinear overlaps.

Main Methods:

• Application of advanced topology-optimization techniques.
• Design of aperiodic, multi-track ring resonators.
• Development of two-dimensional slab microcavities.

Main Results:

• Demonstrated resonators with quality factors Q≳10⁴.
• Achieved small modal volumes V≳(λ/2n)³.
• Obtained large nonlinear overlaps, generalizing phase matching concepts.

Conclusions:

• Topology optimization enables the design of high-performance nonlinear resonators.
• The designed resonators pave the way for efficient, compact, and wide-bandwidth integrated nonlinear devices.
• This work advances the field of integrated nonlinear photonics.