Bloch mode selection in silicon photonic crystal microring resonators

Area of Science:

• Photonics
• Optical Engineering
• Materials Science

Background:

• Silicon-based photonic crystal microring resonators (PhCRs) are key components in integrated optics.
• Controlling and selecting specific optical modes within these resonators is crucial for device performance.
• Existing methods for mode selection can be complex and may limit device miniaturization.

Purpose of the Study:

• To demonstrate a novel method for selecting a subset of Bloch modes in PhCRs.
• To analyze the spatial intensity distribution of Bloch modes for selective out-coupling.
• To enhance design flexibility and reduce the footprint of microring resonator-based devices.

Main Methods:

• Calculation of Bloch modes within silicon-based PhCRs.
• Analysis of intensity beating patterns to differentiate mode characteristics.
• Utilizing an angled output coupler waveguide (CWG) at 90° to the input CWG for selective out-coupling.

Main Results:

• Successful demonstration of selective out-coupling based on spatial intensity distribution.
• Experimental validation showing selection of even-numbered modes and rejection of odd-numbered modes.
• Achieved a high contrast ratio of approximately 9 dB between mode selection and rejection.

Conclusions:

• The demonstrated method provides a new degree of design freedom for ring resonator devices.
• This technique has the potential to significantly reduce the physical size of multiplexers and add-drop filters.
• The selective mode control offers a pathway for more efficient and compact photonic integrated circuits.