Multi-Stage Nonlinear Wavelength Conversion for Laser Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pulsed laser devices face challenges in generating high power pulses with good beam quality and efficiency, particularly in mid-infrared and near-infrared wavelength ranges, due to excessive power loss and noise, limiting their effectiveness in applications such as optical communications and material processing.
Innovation Solution
A method and system utilizing multiple nonlinear stages to convert pump photons into output photons with target wavelengths, achieving efficient power conversion and maintaining good beam quality through spatial overlap and phase-matching techniques, specifically using lithium triborate crystals and a three-step conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-step down-conversion is used, then device complexity is reduced, but power loss increases and beam quality deteriorates
Solution Approach 1:
The patent divides the wavelength conversion process into multiple stages: a first nonlinear stage performing down-conversion from pump wavelength to intermediate wavelength, and a second nonlinear stage performing up-conversion from intermediate wavelength to target wavelength. This segmentation allows each stage to operate with optimized phase-matching conditions, reducing energy loss and improving overall conversion efficiency while maintaining good beam quality.
2Device complexity
If single-step down-conversion is used, then device complexity is reduced, but beam quality deteriorates
Solution Approach 1:
By segmenting the conversion into two stages with an intermediate wavelength step, each nonlinear crystal can be optimized for its specific wavelength range and phase-matching requirements. This results in better preservation of beam quality parameters such as M2 factor and spatial profile compared to single-step conversion.
Solution Approach 2:
The intermediate wavelength acts as a mediator between the pump wavelength and the target wavelength. The first nonlinear stage converts pump photons to intermediate wavelength photons, which then serve as the input for the second nonlinear stage that generates the final target wavelength output. This intermediary step allows for optimized phase-matching in each stage, improving overall beam quality.
3Power
If conventional devices are adapted for high power pulses, then power output is increased, but noise and signal degradation increase
Solution Approach 1:
The multi-stage conversion process allows high power pulses to be converted through intermediate steps, preventing the generation of excessive noise and signal degradation that would occur in single-step high-power conversion. Each stage operates at manageable power levels with optimized phase-matching, reducing unwanted effects such as optical damage, thermal lensing, and generation of unwanted wavelengths.
4Loss of energy
If multi-stage conversion is used, then power loss is reduced and beam quality is improved, but device complexity increases
Solution Approach 1:
The patent implements a two-stage nonlinear conversion system where the first stage performs down-conversion and the second stage performs up-conversion. This segmentation enables optimized phase-matching in each stage, significantly reducing power loss and improving conversion efficiency. The use of standard nonlinear crystals such as LBO or KTP in each stage makes the system practically implementable despite the increased complexity.
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 enables the generation of high power pulses with improved beam quality and efficiency, overcoming the limitations of single-step down-conversion processes by achieving efficient energy transfer and minimizing unwanted light generation, thus enhancing performance in applications requiring eye-safe wavelengths and high peak powers.
Implementation Method 1
converting, by a first nonlinear stage, the at least two photons to a first optical beam comprising a first photon having a first wavelength that is half of the pump wavelength
Implementation Method 2
converting, by at least two second nonlinear stages separated by a gap and based on the seed optical beam, the first photon to a second photon having a second wavelength and a third photon having a target wavelength greater than the pump wavelength
Implementation Method 3
converting, by a third nonlinear stage, the second photon to a fourth photon and a fifth photon each having the target wavelength or having a wavelength within an offset range of the target wavelength
Data Source
AI summary
Disclosed here are methods, devices, and systems for generating an output light beam for a pulsed laser. An example method may comprise generating one or more pump optical beams comprising at least two photons having a pump wavelength. A first nonlinear stage may convert the at least two photons to a first photon having a first wavelength that is half of the pump wavelength. The first optical beam may be caused to spatially overlap with a seed optical beam. At least two second nonlinear stages separated by a gap may be used to convert, based on the seed optical beam, the first photon to a second photon having a second wavelength and a third photon having a target wavelength greater than the pump wavelength. A third nonlinear stage may convert the second photon to a fourth photon and a fifth photon each having the target wavelength or having a wavelength within an offset range of the target wavelength.