Radial Bragg Ring Resonator Non-Periodic Spacing
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Solution Overview
Problem
Conventional optical resonators, such as linear resonators with distributed Bragg reflector mirrors and photonic crystals, suffer from low quality factors and large mode volumes, limiting their integration density, power efficiency, and compatibility with certain materials, while radial Bragg ring resonators face challenges with low quality factors and high vertical losses.
Innovation Solution
A radial Bragg ring resonator structure with a center disc and concentric grating rings spaced non-periodically, where the displacement distance from the center disc to the first grating ring is maximized and decreases radially outward, reducing vertical losses and increasing the quality factor while maintaining a small effective mode volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional radial Bragg ring resonators are used, then the footprint is minimized, but the quality factor is low due to large vertical losses
Solution Approach 1:
The patent applies asymmetry by using non-periodic spacing between grating rings, where the spacing varies radially outward from the center disc. Specifically, the spacing is largest for the first grating ring immediately adjacent to the center disc and decreases in the radially outward direction. This asymmetric, non-uniform spacing profile optimizes the resonator mode distribution to minimize vertical losses while maintaining a compact footprint, thereby achieving high quality factor without increasing device area.
2Ease of manufacture
If linear resonators with distributed Bragg reflector mirrors are used, then the structure is simple to fabricate, but the mode volume is large leading to low optical confinement
Solution Approach 1:
The patent employs curvature by designing a radially symmetric resonator structure with a center disc surrounded by concentric grating rings. This circular geometry provides two-dimensional optical confinement in the radial direction, confining light to a small effective mode volume. The curved radial grating structure maintains fabrication compatibility with standard semiconductor processes while achieving superior optical confinement compared to linear planar resonators.
3Volume of stationary object
If photonic crystals are used, then two-dimensional light confinement is achieved, but a large refractive index contrast is required limiting material choices
Solution Approach 1:
The patent applies local quality by positioning regions of lower index material specifically in the radial spaces between the grating rings, while the grating rings themselves can be formed from various transparent materials. This localized placement of low-index material creates the necessary optical contrast only where needed for radial confinement, while allowing the grating ring material to be selected from BEOL-compatible materials such as silicon, silicon nitride, or other transparent dielectrics, thus achieving two-dimensional confinement with versatile material choices.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves a high quality factor (up to three orders of magnitude increase) and small effective mode volume, enabling efficient light confinement and compatibility with low-index contrast materials, allowing for dense integration and improved performance in optical devices.
Implementation Method 1
radial Bragg ring resonators, which are also known as circular grating resonators (CGRs) or 'fingerprint' structures
Implementation Method 2
optical resonators comprise the central components of light source devices such as, for example, high-efficiency light emitting diodes, lasers, switches, and filters
Implementation Method 3
radial Bragg ring resonators offer full two-dimensional light confinement
Data Source
AI summary
A high quality factor optical resonator structure includes a substrate, a center disc formed on the substrate, and a plurality of concentric grating rings surrounding the center disc. The concentric rings are spaced apart from the center disc and from one another by regions of lower index of refraction material with respect thereto, and wherein spacing between the grating rings and the center disc is non-periodic such that a magnitude of a displacement distance of a given grating ring with respect to a λ/4 Bragg reflector geometry is largest for a first of the grating rings immediately adjacent the center disk and decreases in a radially outward direction.