Polarization-Maintaining Fiber Laser Layout for High Repetition Pulses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber laser devices face challenges in achieving high repetition rate and low excitation power while maintaining a satisfactory waveform due to the need for longer optical fibers and increased internal power density, which complicates the generation of nonlinear effects and self-starting mode lock.
Innovation Solution
A fiber laser device configuration using a first optical fiber with alternating parts of different lengths and mode field diameters, connected in a specific manner to compensate for propagation velocity differences and enhance nonlinear effects, allowing for shorter optical fibers and reduced excitation power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical fiber length is increased to generate sufficient nonlinear effect, then the nonlinear effect is enhanced, but the resonator length increases and the output light frequency cannot be increased (high repetition rate cannot be achieved)
Solution Approach 1:
The patent applies local quality by creating sections of the optical fiber with different mode field diameters. The first optical fiber has a smaller mode field diameter in specific sections to enhance nonlinear effect locally, while other sections have larger mode field diameters to reduce loss. This allows the fiber to simultaneously achieve sufficient nonlinear effect and maintain high repetition rate capability without requiring excessive total length.
Solution Approach 2:
The patent uses composite fiber structure by combining sections with different mode field diameters and different polarization maintaining properties within a single optical fiber system. This composite approach allows different sections to contribute different functions - some sections provide nonlinear effect while others provide low-loss transmission, resolving the contradiction between nonlinear effect enhancement and repetition rate achievement.
2Productivity
If the optical fiber length is decreased to achieve high repetition rate, then the resonator length is reduced and high repetition rate is achieved, but the internal power density increases and high excitation power is required
Solution Approach 1:
The patent applies local quality by creating sections of the optical fiber with different mode field diameters. The first optical fiber has a smaller mode field diameter in specific sections to enhance nonlinear effect locally, while other sections have larger mode field diameters to reduce loss. This allows the fiber to simultaneously achieve sufficient nonlinear effect and maintain high repetition rate capability without requiring excessive total length.
3Reliability
If the optical fiber length is increased to generate sufficient nonlinear effect, then the nonlinear effect is enhanced, but the internal power density increases and high excitation power is required
Solution Approach 1:
The patent applies local quality by creating sections of the optical fiber with different mode field diameters. The first optical fiber has a smaller mode field diameter in specific sections to enhance nonlinear effect locally, while other sections have larger mode field diameters to reduce loss. This allows the fiber to simultaneously achieve sufficient nonlinear effect and maintain high repetition rate capability without requiring excessive total length.
4Use of energy by stationary object
If the optical fiber is configured with alternating parts of different lengths and mode field diameters connected in specific manner, then the nonlinear effect is enhanced and excitation power is reduced, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the first optical fiber into multiple sections with alternating different mode field diameters. These segmented sections are connected in series to form the complete optical fiber. This segmentation allows each section to contribute differently to the overall performance - some sections enhance nonlinear effect while others reduce loss, achieving the balance between excitation power and device complexity.
Solution Approach 2:
The patent applies parameter changes by varying the mode field diameter parameter along the length of the optical fiber. The mode field diameter is changed between sections to optimize the balance between nonlinear effect and loss. This parameter variation allows the fiber to achieve sufficient nonlinear effect with shorter total length, thereby reducing excitation power requirements while managing device 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 configuration enables the output of light with a satisfactory waveform and high repetition rate at low excitation power, improving manufacturing yield and reducing connection losses between fibers with different mode field diameters.
Implementation Method 1
the first optical fiber includes at least one first part and at least two second parts alternatively disposed with the first part, the first part and the second part adjacent to each other are connected to each other such that a fast axis of the first part coincides with a slow axis of the second part at a connection point
Implementation Method 2
Known as a fiber laser device is one that generates an ultrashort pulse laser by causing mode lock using the nonlinear effect of an optical fiber
Data Source
AI summary
A fiber laser device includes a first optical fiber, a second optical fiber, and a third optical fiber configured by polarization maintaining fibers. The first optical fiber includes at least one first part and at least two second parts alternatively disposed with the first part. The first part and the second part adjacent to each other are connected to each other such that a fast axis of the first part coincides with a slow axis of the second part at a connection point. A total length of the first part is equal to a total length of the second parts. A mode field diameter of the first optical fiber is smaller than each of a mode field diameter of the second optical fiber and a mode field diameter of the third optical fiber.