Curved-Mirror Optical Oscillator for High-Power Beam Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical oscillators face a challenge in achieving high output power while maintaining beam quality due to thermal lens effects and higher-order mode oscillation when using planar mirrors for resonators, which deteriorate beam quality (M²).
Innovation Solution
An optical oscillator design featuring a first reflecting portion and a second reflecting portion forming an unstable resonator, where the second reflecting portion is smaller and curved towards the first, allowing light to diverge and pass through a wider laser medium region, facilitating stimulated emission and higher output power with suppressed beam quality deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If planar mirrors are used for resonator to simplify structure, then device complexity is reduced, but beam quality deteriorates due to thermal lens effect reducing laser mode radius
Solution Approach 1:
The patent applies curvature to the output mirror (second reflecting portion) to counteract the thermal lens effect. By making the output mirror curved with a specific radius of curvature, the optical path is corrected to maintain a stable laser mode radius despite thermal lensing in the ceramic laser medium, thereby preserving beam quality while using a simplified resonator structure.
2Power
If excitation area is expanded to increase output power, then power is improved, but beam quality deteriorates due to higher-order mode oscillation
Solution Approach 1:
The patent changes the curvature parameter of the output mirror to optimize the balance between output power and beam quality. By adjusting the radius of curvature of the output mirror, the system can accommodate larger excitation areas while maintaining fundamental mode oscillation, thus achieving high output power without higher-order mode deterioration.
Solution Approach 2:
The patent applies different curvature characteristics to different parts of the resonator system. The output mirror has a specific curved surface with optimized radius of curvature, while other components maintain their standard configurations. This localized optimization allows the excitation area to be expanded without causing higher-order mode oscillation, as the curved mirror compensates for thermal effects in the high-power region.
3Volume of moving object
If curved mirror is used to expand light passage area, then volume of laser medium utilization is improved, but device complexity increases
Solution Approach 1:
The patent implements a curved output mirror with a specifically optimized radius of curvature that allows the laser beam to pass through a wider region of the laser medium. This single curved mirror design expands the effective light passage area and stimulates more emission without requiring multiple mirrors or complex resonator configurations, thus increasing volume utilization while keeping device complexity manageable.
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 design achieves high output power with improved beam quality by enhancing stimulated emission and controlling thermal lens effects, enabling stable pulsed laser light output.
Implementation Method 1
a saturable absorption portion (16) having a second end surface (16b) opposite to the first end surface (16a) in the direction (Z-axis)
Implementation Method 2
a laser medium (14) configured to emit light having a second wavelength due to incidence of light having a first wavelength
Implementation Method 3
the second reflecting portion (12) is curved toward the first reflecting portion (10)... the light having the second wavelength reflected by the second reflecting portion diverges
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An optical oscillator according to an embodiment includes a first reflecting portion that transmits light having a first wavelength and reflects light having a second wavelength different from the first wavelength, a second reflecting portion that forms an unstable resonator together with the first reflecting portion and reflect light having the second wavelength, a laser medium that is disposed between the first reflecting portion and the second reflecting portion and emits light having the second wavelength due to incidence of light having the first wavelength, and a saturable absorption portion disposed on a side opposite to the first reflecting portion when viewed from the laser medium in the one direction, the first reflecting portion includes an incidence surface on which light having the first wavelength is incident, on a side opposite to the laser medium, a size of the second reflecting portion is smaller than a size of the first reflecting portion when viewed in the one direction, at least a part of a surface of the saturable absorption body on the side opposite to the laser medium includes a curved region curved toward the laser medium side, and the second reflecting portion is a dielectric multilayer film provided in the curved region.