Fiber Laser Rise Time Control via Preliminary Pumping
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Solution Overview
Problem
Fiber laser devices require a significant time for laser light intensity to stabilize, leading to inefficiencies in machining and medical applications, as existing solutions like constant low-intensity pumping before output can result in unnecessary light emission and unstable rare earth element pumping.
Innovation Solution
A fiber laser device with a controller that manages seed and pumping light sources to transition from a preliminary pumping state to an output state, where the seed laser light is only input during the output state, ensuring stimulated emission and wavelength conversion, while suppressing spontaneous emission in the preliminary state using a wavelength converter and filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If constant low-intensity pumping light is input to the amplification optical fiber during standby state period, then the rise time of laser light is shortened, but spontaneous emission light is amplified and output causing unnecessary light emission
Solution Approach 1:
The patent applies preliminary action by pre-pumping the rare earth elements in the amplification optical fiber during a standby period before actual laser output is needed. This prepares the gain medium in advance, so when the seed laser is activated, the amplification can occur immediately with minimal rise time. The controller manages the pumping light source to maintain the rare earth elements in a pumped state ready for rapid laser generation.
Solution Approach 2:
The patent extracts and separates the spontaneous emission light from the desired laser output by using a wavelength selecting filter. This filter is configured to transmit only the specific wavelength of the seed laser light while blocking other wavelengths including spontaneous emission. This allows the system to benefit from pre-pumping while eliminating the harmful effect of amplified spontaneous emission through selective wavelength filtering.
2Productivity
If pumping light is input in standby state, then rare earth elements are pumped in advance, but light output occurs except for the output period
Solution Approach 1:
The system performs preliminary pumping of the rare earth elements during standby periods when no laser output is required. The controller manages the pumping light source to maintain the gain medium in a ready state, enabling rapid laser generation when needed. This preliminary preparation improves productivity by minimizing the rise time while the wavelength selecting filter prevents energy waste by blocking spontaneous emission light during standby.
Solution Approach 2:
The controller implements feedback control by monitoring the operational state of the fiber laser device and adjusting the pumping light intensity accordingly. When the device is in standby mode, the controller reduces pumping to minimal levels sufficient to maintain readiness without causing significant spontaneous emission. During active output, the controller increases pumping intensity to support high-power laser generation, thereby optimizing energy efficiency through state-dependent control.
3Loss of time
If high-intensity pumping light is used to shorten rise time, then laser light intensity stabilizes faster, but spontaneous emission increases and wavelength conversion may occur
Solution Approach 1:
The patent uses the wavelength selecting filter to extract and block wavelength-converted light generated by spontaneous emission from high-intensity pumping. The filter is configured to transmit only the desired seed laser wavelength while blocking other wavelengths. This allows the system to use high-intensity pumping for rapid stabilization without the harmful effect of wavelength-converted spontaneous emission reaching the output, as it is filtered out before exiting the device.
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 shortens the rise time of laser light output and minimizes unnecessary light emission, enhancing operational efficiency and stability in fiber laser devices.
Implementation Method 1
the amplification optical fiber is configured to amplify the seed laser light and output the amplified light as laser light, wherein the amplification optical fiber is doped with rare earth elements that are pumped by the pumping light
Implementation Method 2
a wavelength converter to which the laser light output from the amplification optical fiber is input and which is configured to convert a wavelength of light having an intensity equal to or higher than a predetermined intensity
Implementation Method 3
a wavelength selecting filter to which the laser light output from the wavelength converter is input and which is configured to transmit light whose wavelength is converted by the wavelength converter and to suppress transmission of light whose wavelength is not converted by the wavelength converter
Data Source
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AI summary
[Object] A fiber laser device capable of shortening the rise time of output laser light and suppressing laser light output except for an output period is provided. [Means to attain the object] A fiber laser device 100 includes: a seed laser light source 10, a pumping light source 20, an amplification optical fiber 30, a wavelength converter 71, a wavelength selecting filter 73, an output section 50, and a controller 60. The controller 60 controls the seed laser light source 10 and the pumping light source 20 to change from a preliminary pumping state to an output state. In the preliminary pumping state, the laser light is not output from the seed laser light source 10, the pumping light is output from the pumping light source 10, and the pumping light has such an intensity that the wavelength of the laser light emitted and output from the amplification optical fiber 30 is not converted by the wavelength converter 71. In the output state, the laser light is output from the seed laser light source 10, the pumping light is output from the pumping light source 20, and the laser light and the pumping light have such intensities that the wavelength of the laser light amplified and output by the amplification optical fiber 30 is converted by the wavelength converter 71.