Resonantly Enhanced Frequency Converter Cavity Design
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Solution Overview
Problem
Existing frequency conversion systems using nonlinear crystals in external cavity resonators face issues with crystal damage due to high optical power density, leading to reduced crystal lifetime and inefficiencies in impedance matching across varying input powers.
Innovation Solution
The nonlinear crystal is positioned outside the traditional beam waist, either in a divergent or collimated beam, reducing optical power density and allowing for impedance matching across a range of input powers without modifying physical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the nonlinear crystal is positioned in the beam waist to achieve high frequency conversion efficiency, then the conversion efficiency is improved, but the optical power density inside the crystal and at the output face increases causing crystal damage and reduced lifetime
Solution Approach 1:
The patent applies dynamics by making the resonator cavity length adjustable rather than fixed. The cavity length can be dynamically changed to accommodate different input powers while maintaining impedance matching. This is achieved through a translation stage that allows precise positioning of optical components, enabling the system to adapt to varying operating conditions without compromising crystal reliability or conversion efficiency
Solution Approach 2:
The patent changes the parameter of cavity length to resolve the contradiction. By varying the cavity length, the system can maintain optimal impedance matching across different input powers while avoiding excessive power density buildup that would damage the crystal. This parameter adjustment allows the crystal to operate in a safe power density regime while still achieving high conversion efficiency
2Productivity
If the resonator is impedance matched for a specific input power using fixed physical components, then the conversion efficiency is optimized, but the system cannot adapt to different input powers requiring component replacement or modification
Solution Approach 1:
The patent implements dynamics by making the resonator cavity length adjustable through a translation stage. This allows the system to dynamically adapt to different input powers by changing the cavity length, thereby maintaining impedance matching and optimal conversion efficiency across a wide range of operating conditions without requiring physical component changes
Solution Approach 2:
The patent achieves universality by designing a single resonator system that can handle multiple input power levels. The adjustable cavity length enables one physical configuration to serve multiple functions - optimizing performance for different input powers - eliminating the need for multiple specialized components or frequent replacements
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 configuration significantly extends the crystal's lifetime and maintains high frequency conversion efficiency, achieving over 90% efficiency while reducing power density by an order of magnitude, facilitating adaptable and cost-effective manufacturing.
Implementation Method 1
frequency conversion of laser radiation by means of non-linear interaction of laser radiation with a suitable non-linear crystal
Implementation Method 2
The placement of crystal 12 in the beam's waist provides high frequency conversion efficiency
Data Source
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AI summary
A frequency converter for converting a single mode input beam at a fundamental frequency to an output beam at a converted frequency is configured with a plurality of spaced optical components defining a resonant cavity. The optical components shape the input beam with at least one beam waist in the cavity. The frequency converter further includes a non-linear crystal located within the cavity in either a divergent beam with a Rayleigh range smaller than a cavity round trip length so that a center of the crystal is spaced from the beam, waist along a beam path, or in a collimated beam with a Rayleigh range greater than the cavity round trip length