Asymmetric Whispering Gallery Resonator for Side Mode Suppression
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Solution Overview
Problem
Conventional disk resonators used in lidar systems often have side modes near the working mode, leading to reduced production yield due to their unusability.
Innovation Solution
The development of asymmetric whispering gallery mode resonators with a fundamental mode located in a midplane that is non-coextensive with another midplane, which shifts or tilts the fundamental mode position to suppress side modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional disk resonators are used, then the resonator can support multiple modes per free spectral range, but side modes appear near the working mode rendering the resonator unusable
Solution Approach 1:
The patent applies asymmetry by making the resonator disk thickness non-uniform, specifically creating a convex side structure where the thickness varies along the perimeter. This asymmetric thickness distribution shifts different modes to different positions, separating the fundamental mode from side modes, thereby eliminating the harmful side modes that render conventional symmetric resonators unusable.
2Manufacturing precision
If disk resonator geometry varies due to limited fabrication precision, then mode positions cannot be accurately controlled, but this leads to side modes appearing near the working mode
Solution Approach 1:
The asymmetric thickness design creates a unique mode position fingerprint for each mode. The fundamental mode and side modes are separated in position due to the varying thickness, so even with fabrication tolerances, the modes remain distinguishable and the fundamental mode can be reliably identified and used.
3Device complexity
If the fundamental mode is positioned in the midplane equidistant from top and bottom surfaces, then the resonator structure is symmetric, but side modes cannot be suppressed
Solution Approach 1:
The patent deliberately breaks the symmetry by creating a convex side structure where the resonator thickness varies. This asymmetry causes the fundamental mode to be positioned at a different location than side modes, enabling side mode suppression while maintaining a relatively simple disk resonator structure that is easy to fabricate.
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 effectively suppresses side modes by positioning them closer to electrodes, resulting in improved resonator production yield and performance in lidar systems.
Implementation Method 1
light from the laser is provided to the resonator, circulates inside the resonator undergoing total internal reflection
Implementation Method 2
asymmetric whispering gallery mode resonator disk formed of a transparent material
Data Source
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AI summary
An asymmetric whispering gallery mode resonator device is described. The resonator device includes an asymmetric whispering gallery mode resonator disk (e.g., transparent material, electrooptic material). The resonator disk includes an axial surface along a perimeter of the resonator disk, a top surface, and a bottom surface. A first midplane passes through the axial surface dividing the axial surface into symmetrical halves. The top surface and the bottom surface are substantially parallel, and a second midplane is substantially equidistant between the top surface and the bottom surface. The first midplane and the second midplane are non-coextensive. The asymmetric whispering gallery mode resonator disk can further include a first chamfered edge between the top surface and the axial surface, and a second chamfered edge between the bottom surface and the axial surface. Moreover, the resonator device includes a first electrode on the top surface and a second electrode on the bottom surface.