Elliptical Whispering Gallery Mode Microcavity for Single-Mode Lasing
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Solution Overview
Problem
Conventional methods for preparing single-mode micro-lasers with low thresholds and narrow linewidths are complex and not cost-effective, particularly when using coupled optical microcavities, which hinders the development of optoelectronic integration technology.
Innovation Solution
A method involving the preparation of a single whispering gallery mode optical microcavity using dry etching and chemical polishing, coupled with an optical fiber cone or waveguide, to achieve single-mode lasing with a low threshold and narrow linewidth by selectively reducing the quality factor of the fundamental spatial mode and exciting a coherently combined mode with a high quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the size of the whispering gallery mode optical microcavity is reduced to sub-micron order to suppress mode numbers for single-mode lasing, then the mode number is suppressed, but the bending radiation loss increases, quality factor decreases, and pump threshold increases
Solution Approach 1:
The patent changes the geometric parameters of the microcavity by introducing an elliptical deformation to the circular cavity. This parameter change allows the cavity to maintain a larger effective size while still suppressing higher-order modes, thereby reducing bending radiation loss and improving the quality factor without sacrificing single-mode lasing capability
Solution Approach 2:
The patent introduces asymmetry by deforming the circular microcavity into an elliptical shape. This asymmetric geometry creates a unique mode structure where only the fundamental mode can be excited through the asymmetric coupling, while higher-order modes are suppressed. The asymmetry also reduces the curvature at certain points, lowering bending radiation loss
2Manufacturing precision
If the size of the whispering gallery mode optical microcavity is reduced to sub-micron order to suppress mode numbers for single-mode lasing, then the mode number is suppressed, but the quality factor decreases and pump threshold increases
Solution Approach 1:
The patent changes the geometric parameters of the microcavity by introducing an elliptical deformation to the circular cavity. This parameter change allows the cavity to maintain a larger effective size while still suppressing higher-order modes, thereby reducing bending radiation loss and improving the quality factor without sacrificing single-mode lasing capability
Solution Approach 2:
The patent introduces asymmetry by deforming the circular microcavity into an elliptical shape. This asymmetric geometry creates a unique mode structure where only the fundamental mode can be excited through the asymmetric coupling, while higher-order modes are suppressed. The asymmetry also reduces the curvature at certain points, lowering bending radiation loss
3Reliability
If coupled optical microcavities are used to achieve single-mode lasing with low threshold and narrow linewidth, then the lasing performance is improved, but the preparation process becomes complicated and cost-effective preparation is hindered
Solution Approach 1:
The patent extracts the essential function of coupled cavities (mode suppression and single-mode lasing) and implements it through a single deformed cavity. By taking out the coupling structure and incorporating its functionality into the geometry of a single cavity, the patent simplifies the device structure and preparation process while maintaining the desired lasing performance
Solution Approach 2:
The patent segments the complex coupled-cavity system into a simpler single-cavity system with modified geometry. Instead of preparing and coupling multiple cavities, the invention uses a single elliptically deformed cavity that achieves the same functional results through geometric segmentation of the mode structure
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
The method simplifies the preparation process while achieving single-mode lasing with a low threshold and narrow linewidth, enhancing the quality factor and reducing mode competition, thereby improving the application level of optoelectronic integration technology.
Implementation Method 1
the whispering gallery mode optical microcavity can realize confinement of the photons through continuous total internal reflection of light at the interface between the cavity material and the surrounding material with lower refractive index
Implementation Method 2
preparing an optical microcavity containing a gain material by dry etching
Implementation Method 3
chemical polishing technology is also adopted, so as to obtain an active optical microcavity with a low loss and a high Q value
Implementation Method 4
through coupling and integration of an optical fiber cone or an optical waveguide, the single-mode micro-laser with a narrow line width and a low threshold can be obtained
Data Source
AI summary
A single-mode micro-laser based on a single whispering gallery mode optical microcavity and a preparation method thereof described includes: preparing a desired single whispering gallery mode optical microcavity doped with rare earth ions or containing a gain material such as quantum dots, wherein an optical microcavity configuration include a micro-disk cavity, a ring-shaped microcavity, and a racetrack-shaped microcavity; a material type include lithium niobate, silicon dioxide, silicon nitride, etc.; preparing an optical fiber cone or an optical waveguide of a required size which can excite high-order modes of the optical microcavity, such as a ridge waveguide and a circular waveguides; and coupling, integrating, and packaging the optical fiber cone or the optical waveguide with the microcavity. A pump light is coupled to the optical fiber cone or the optical waveguide to excite a compound mode with a polygonal configuration.