Filter Element for Fiber Laser Stokes Light Attenuation
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Solution Overview
Problem
Fiber laser apparatuses face instability in laser light oscillation due to Stokes light and anti-Stokes light resulting from four-wave mixing in multi-mode fibers, which can cause issues with pump light sources and affect the reliability of the amplifying optical fiber.
Innovation Solution
A filter element is configured to cause a loss of Stokes light and anti-Stokes light by preferentially attenuating light within specific wavelength ranges that include the peak wavelengths of these components, thereby reducing their power and stabilizing the laser light oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a multi-mode fiber is used to guide laser light, then the laser apparatus can achieve higher power output, but Stokes light and anti-Stokes light generated by four-wave mixing cause instability in laser light oscillation and troubles to the pump light source
Solution Approach 1:
The patent extracts and removes the harmful Stokes light and anti-Stokes light components from the laser beam using a filter. The filter is configured to transmit the desired laser wavelength while blocking the specific wavelength ranges where Stokes and anti-Stokes light occur, thereby separating the useful laser light from the harmful scattered light components that cause oscillation instability and pump source troubles.
Solution Approach 2:
The patent introduces a filter as an intermediary component between the multi-mode fiber and the subsequent optical components. This filter acts as a mediator that selectively transmits the laser wavelength while blocking the harmful Stokes and anti-Stokes light, preventing the four-wave mixing products from reaching the pump light source and causing instability without affecting the primary laser output.
2Power
If a multi-mode fiber is used to guide laser light, then the laser apparatus can achieve higher power output, but Stokes light and anti-Stokes light cause troubles to the pump light source
Solution Approach 1:
The filter extracts and removes the harmful Stokes and anti-Stokes light components before they can reach the pump light source. By configuring the filter to block specific wavelength ranges corresponding to these scattered light components while transmitting the desired laser wavelength, the patent prevents the four-wave mixing products from causing damage or interference to the pump light source.
Solution Approach 2:
The filter serves as an intermediary protective component positioned between the multi-mode fiber and the pump light source. It mediates the optical interaction by selectively transmitting the laser wavelength while blocking the harmful Stokes and anti-Stokes light, thereby protecting the pump light source from the adverse effects of four-wave mixing without compromising the laser power output.
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 filter element effectively reduces the power of Stokes light and anti-Stokes light, enhancing the stability of laser light oscillation and improving the reliability of the pump light sources by minimizing their impact on the amplifying optical fiber.
Implementation Method 1
Stokes light and anti-Stokes light resulting from four-wave mixing in which a plurality of guide modes are involved
Implementation Method 2
scattered light generated by stimulated Raman scattering (stimulated Raman scattering is a kind of nonlinear optical effect)
Data Source
AI summary
A fiber laser apparatus includes a pump light source that emits pump light; a pump delivery fiber that guides the pump light; an amplifying optical fiber that is optically coupled to the pump delivery fiber and guides laser light; and a filter element that causes more loss of light of a wavelength range that includes a peak wavelength of at least one of Stokes light and anti-Stokes light than the laser light. The Stokes light and anti-Stokes light result from four-wave mixing involving a plurality of guide modes in a multi-mode fiber that guides the laser light. The filter element is disposed between: the pump delivery fiber and the amplifying optical fiber, the amplifying optical fiber and the multi-mode fiber, or at the multi-mode fiber.