Optical Fiber Laser Return Light Attenuation via Thermal Conversion
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Solution Overview
Problem
Optical fiber laser devices face issues with return light damage due to unforeseeable and amplified reflected laser light, which can lead to damage of composing parts and safety concerns, especially when high-power return light is emitted from the end portion.
Innovation Solution
An optical fiber laser device is designed with a return-light-attenuating portion that includes a thermal conversion unit to convert return light into heat, a temperature-monitoring device to measure the temperature increase, and a control unit that decreases or stops the laser output when the temperature reaches a predetermined threshold, effectively mitigating the damage from return light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return light countermeasure with specific power and wavelength is adopted, then the return light can be attenuated, but the return light may still be amplified and have different wavelengths, causing the countermeasure to be ineffective
Solution Approach 1:
The patent changes the parameter of the countermeasure from fixed specific power and wavelength to a broadband approach that handles various powers and wavelengths. The return light attenuating portion is designed to attenuate return light across a broad wavelength range, adapting to different return light conditions that may arise from workpiece reflections, fiber cracks, or defects at various locations in the optical path.
2Device complexity
If the return light is allowed to propagate, then the device structure remains simple, but the return light may damage composing parts of the optical fiber laser device
Solution Approach 1:
The patent extracts the return light from the optical path by introducing a return light attenuating portion that removes or attenuates the return light before it can reach and damage composing parts such as the laser diode, optical amplifiers, or other sensitive components in the optical fiber laser device.
Solution Approach 2:
The return light attenuating portion acts as an intermediary element inserted into the optical path between the workpiece (or potential defect locations) and the sensitive composing parts. This intermediary component attenuates the return light, protecting the composing parts while allowing the main laser beam to pass through with minimal loss.
3Power
If high power return light is emitted from the end portion, then the output capability is maintained, but safety concerns arise and components may be damaged
Solution Approach 1:
The patent converts the harmful return light into a detectable signal by using a temperature monitoring device that measures temperature changes in the return light attenuating portion. The temperature increase caused by absorbed return light serves as an indicator of return light presence and intensity, allowing the control unit to take protective actions before damage occurs.
Solution Approach 2:
The patent implements a feedback control system where the temperature monitoring device continuously monitors the temperature of the return light attenuating portion, and the control unit adjusts the laser output based on the temperature readings. When the temperature exceeds a predetermined threshold, the control unit decreases or stops the laser output, preventing damage to components and ensuring safety.
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 effectively attenuates return light, preventing damage to the optical fiber laser device components and ensuring safety by controlling the output based on temperature thresholds, thereby enhancing the durability and output capability of the device.
Implementation Method 1
a thermal conversion unit provided at the return-light-attenuating portion and configured to convert the return light into heat
Implementation Method 2
a temperature-monitoring device configured to measure an increase in a temperature, of the return-light-attenuating portion, caused by the heat converted by the thermal conversion unit
Implementation Method 3
a control unit configured to decrease or stop an output of the laser light when the temperature measured by the temperature-monitoring device becomes a predetermined threshold temperature or higher
Data Source
AI summary
An optical fiber laser device generates laser light by using an optical amplifying fiber as an amplification medium in a laser oscillator and includes: an optical outputting fiber configured to emit laser light to an outside; a return-light-attenuating portion configured to perform an attenuation process to return light propagating through at least the optical outputting fiber in a reverse direction of the laser light; a thermal conversion unit provided at the return-light-attenuating portion and configured to convert the return light into heat; a temperature-monitoring device configured to measure an increase in a temperature, of the return-light-attenuating portion, caused by the heat converted by the thermal conversion unit; and a control unit configured to decrease or stop an output of the laser light when the temperature measured by the temperature-monitoring device becomes a predetermined threshold temperature or higher.