Whispering Gallery Microcavity Lasing for Tunable Narrow-Linewidth Microwaves
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Solution Overview
Problem
Existing dual-wavelength microcavity lasers face challenges in achieving stable, tunable spacing and narrow linewidth due to mode competition and longitudinal mode instability.
Innovation Solution
A tunable microwave source based on dual-wavelength lasing of a single optical whispering gallery microcavity, utilizing quasi-degenerate multi-localized periodic orbits with a π-phase difference to suppress mode competition, and employing optical waveguide amplification, filtration, and high-speed detection to generate stable, tunable microwave signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical whispering gallery microcavity is used to generate dual-wavelength lasing, then the structure becomes simpler and smaller, but achieving stable dual-wavelength lasing with tunable spacing and narrow linewidth is difficult due to mode competition
Solution Approach 1:
The patent introduces asymmetric perturbation to the microcavity by removing an arched boundary (corresponding to at most a central angle of 18-degree) through linear cutting. This asymmetric modification breaks the degeneracy of whispering gallery modes, creating quasi-degenerate polygon modes with slightly different frequencies that can lase simultaneously without severe mode competition, thus achieving stable dual-wavelength output with tunable spacing
Solution Approach 2:
The patent changes the geometric parameters of the microcavity by removing a specific arched boundary segment. This parameter change modifies the mode distribution and frequency spacing within the cavity, enabling the generation of dual-wavelength lasing with adjustable spacing while maintaining narrow linewidth and high stability
2Adaptability or versatility
If conventional multi-longitudinal mode laser is used, then dual-wavelength lasing can be achieved, but signal instability occurs due to mode competition
Solution Approach 1:
By introducing asymmetric perturbation through linear cutting, the patent creates quasi-degenerate polygon modes that have slightly different frequencies and spatial distributions. This asymmetry reduces the gain competition between modes, allowing both modes to lase stably simultaneously, thereby achieving both dual-wavelength capability and signal stability
Solution Approach 2:
The patent applies local modification by removing only a specific arched boundary segment (at most 18-degree central angle) rather than uniformly modifying the entire cavity. This localized asymmetric perturbation is sufficient to split the degenerate modes while maintaining the overall high Q-factor of the microcavity, ensuring stable dual-wavelength lasing
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 solution achieves stable dual-wavelength lasing with adjustable spacing and narrow linewidth, providing a simple, small-sized, and cost-effective tunable microwave source with high quality factor and low pump threshold.
Implementation Method 1
an optical waveguide or a tapered optical fiber which is directly connected, laterally or vertically coupled with the single optical whispering gallery microcavity through evanescent waves for inputting pump light
Implementation Method 2
The optical microcavity laser represented by the whispering gallery microcavity laser uses the continuous total internal reflection of light on the smooth side wall to realize the strong binding on the light field
Implementation Method 3
the microwave signal with good stability and narrow line width is able to be obtained by the beat frequency due to the relatively low phase fluctuations between two lasing-modes in the single microcavity
Data Source
AI summary
A tunable microwave source based on dual-wavelength lasing of a single optical whispering gallery microcavity includes a dual-wavelength laser having the single optical whispering gallery microcavity for generating dual-wavelength lasing with adjustable spacing, narrow linewidth and low threshold; an optical fiber or waveguide amplifier for optical signal amplification; an optical filter for optical signal and noise filtration; and a high-speed detector for generating a tunable microwave signal with narrow bandwidth. The dual-wavelength laser includes a pump source, the optical whispering gallery microcavity, an optical waveguide or a tapered optical fiber, a microcavity substrate, and a gold electrode pair. The frequency spacing of the dual-wavelength lasing is tuned by adjusting the external voltage of the gold electrode pair.