High-order mode suppression in a high-Q disk resonator with metal patterning

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• High-quality (Q) resonators are crucial for silicon photonics, but conventional microring resonators (MRRs) and microdisk resonators (MDRs) suffer from high losses and mode interference.
• Existing designs struggle to balance high Q-factors with clean spectral responses.

Purpose of the Study:

• To introduce a novel microdisk resonator (MDR) design that overcomes the limitations of conventional resonators.
• To achieve a high Q-factor and a clean spectral response simultaneously using a patterned metal layer.

Main Methods:

• Integration of a patterned nickel (Ni) metal layer onto a conventional MDR.
• Utilizing the optical absorption properties of the Ni layer to selectively suppress high-order modes.
• Experimental characterization of the patterned MDR's performance.

Main Results:

• The patterned MDR achieved a high Q-factor of 1.5 × 10^5, two orders of magnitude higher than comparable MRRs.
• A maximum extinction ratio of 31 dB was recorded for a 20 μm radius patterned MDR.
• The design successfully combined a high Q-factor with a clean spectral response.

Conclusions:

• The novel patterned MDR design effectively suppresses high-order modes, leading to significantly enhanced Q-factors.
• This approach offers a promising solution for high-Q resonators in chip-scale photonic systems.
• The integrated Ni layer provides a pathway for improved performance in silicon photonics applications.