FDFA Polarization Stabilization via Wavelength Plates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light source devices using solid-state lasers face challenges in maintaining the intensity and polarization state of the output laser beam, leading to inefficient feedback control and reduced wavelength conversion efficiency due to changes in pump light intensity.
Innovation Solution
The polarization state of the input light is adjusted to minimize changes in the output light's polarization state, even with variations in amplification factor, using a polarization state adjusting optical element with wavelength plates to maintain constant conversion efficiency and stable feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pump light intensity is increased to maintain output laser beam intensity, then the output intensity is improved, but the polarization state changes significantly causing feedback control divergence
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the polarization state of the input light to a specific orientation (parallel to the fast axis of the polarization-maintaining optical fiber) before amplification. This preliminary setup ensures that even when pump light intensity varies, the polarization state of the output light remains stable, preventing feedback control divergence while allowing output intensity to be maintained at target values.
2Ease of operation
If the amplification factor is changed to control output light intensity, then the output intensity control is improved, but the polarization state of output light changes reducing wavelength conversion efficiency
Solution Approach 1:
The patent applies parameter changes by specifically setting the polarization state parameter of the input light (orienting it parallel to the fast axis) and using a polarization-maintaining optical fiber with specific birefringence characteristics. These parameter choices ensure that amplification factor changes for intensity control do not significantly affect polarization state, thereby maintaining wavelength conversion efficiency while enabling flexible output intensity control.
3Illumination intensity
If the pump light intensity is increased to compensate for polarization changes, then the output intensity is maintained, but the polarization state instability increases causing system divergence
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the polarization state of the input light to a specific orientation (parallel to the fast axis of the polarization-maintaining optical fiber) before amplification. This preliminary setup ensures that even when pump light intensity varies, the polarization state of the output light remains stable, preventing feedback control divergence while allowing output intensity to be maintained at target values.
Solution Approach 2:
The patent uses a polarization-maintaining optical fiber as an intermediary element between the input light and the amplification process. This intermediary component with specific birefringence characteristics actively maintains the polarization state during amplification, decoupling the relationship between pump light intensity changes and polarization state changes, thereby preventing system divergence.
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 approach ensures that the polarization state of the output light remains stable, maintaining high wavelength conversion efficiency and enabling effective feedback control, even with changes in pump light intensity, thereby ensuring consistent output.
Implementation Method 1
optically amplifying an input light by a polarization-maintaining optical fiber amplifier
Implementation Method 2
the light passes through a wavelength conversion optical system to come into an output light having a target wavelength
Implementation Method 3
The polarization state of the input light is adjusted to minimize changes in the output light's polarization state, even with variations in amplification factor, using a polarization state adjusting optical element with wavelength plates
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A polarization state adjusting optical element (2) is formed by a 1/2 wavelength plate and a 1/4 wavelength plate and its polarization direction and elliptic degree are adjusted. By adjusting the polarization state adjusting optical element (2) in advance, even if the output of a pump light source (8) is changed, the polarization characteristic (polarization direction and elliptic degree) of the output light of an FDFA amplifier (3) will not change or the change is sufficiently small. In this state, a polarization state adjusting optical element (4) adjusts the polarization state of the laser beam coming into a wavelength conversion optical system (5) so that the wavelength conversion optical system (5) has the maximum conversion efficiency. Thus, it is possible to provide an FDFA having a small change of the polarization state of the output light even if the pump light intensity is changed.