CO2 Slab Laser Recess Mode Selection
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Solution Overview
Problem
Existing CO2 slab waveguide lasers face limitations in mode quality and output power due to restricted electrode spacing and manufacturing complexities, with existing designs requiring precise electrode curvature and alignment, which are difficult to maintain and affect beam quality.
Innovation Solution
Incorporating a recess on the surface of the waveguide to create a region for free space propagation, allowing for mode selection by varying the recess's position and size, which enables the selection of the fundamental mode without the need for precise electrode curvature and alignment, and allows for increased electrode spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precise electrode curvature and alignment are used to achieve fundamental mode selection, then mode quality is improved, but manufacturing complexity and alignment difficulty increase
Solution Approach 1:
The patent extracts the mode selection function from the electrodes and places it in a separate optical element (such as a curved mirror or cylindrical lens) positioned in the resonator. This separation allows the electrodes to focus solely on generating the laser medium without bearing the complexity of precise curvature and alignment requirements for mode selection, thereby improving manufacturability while maintaining fundamental mode quality.
Solution Approach 2:
The patent introduces an intermediary optical element between the electrodes and the resonator cavity that performs the mode selection function. This intermediary component (such as a curved output coupler or dedicated mode-selecting lens) mediates between the electrode-generated plasma and the resonator, providing fundamental mode selection without requiring the electrodes themselves to have precise curvature and alignment.
2Power
If electrode spacing is increased to improve output power, then power output is improved, but mode selection capability deteriorates
Solution Approach 1:
The patent addresses the limitation of electrode spacing by introducing mode selection in a different dimension - through the use of optical elements with specific curvatures or focal lengths positioned in the resonator. This allows the electrode spacing to be optimized for power output while the mode selection is achieved through the optical dimension, decoupling these two previously conflicting requirements.
3Stability of the object's composition
If fixed waveguide structure is used to maintain mode quality, then mode stability is improved, but adaptability to thermal expansion deteriorates
Solution Approach 1:
The patent employs dynamic or adjustable optical elements in the resonator that can compensate for thermal expansion of the waveguide structure. For example, adjustable mirrors or lenses allow the resonator geometry to be tuned after assembly, maintaining mode quality despite thermal dimensional changes in the fixed waveguide, thereby providing both stability and adaptability.
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 improves mode selection and stability, allowing for higher output power while simplifying manufacturing and reducing the impact of thermal effects and misalignment, resulting in a more reliable and efficient laser operation.
Implementation Method 1
a recess is located on at least one of said surfaces, said recess being configured to create a region within said waveguide in which free space propagation occurs
Implementation Method 2
a discharge region contained within at least a portion of said waveguide; an excitation means for energising the electrodes to excite the lasing gas
Implementation Method 3
a resonant cavity having a propagation axis orthogonal to said first axis
Data Source
AI summary
A mode selection technique in a laser is described wherein a recess is formed in a surface of a waveguide in the laser. The recess provides a region of free space propagation within the waveguide which preferentially selects the lowest order mode. A mode selective RF excited CO2 slab laser, having a stable resonator in the waveguide dimension and a negative branch unstable resonator in the non-waveguide dimension, is constructed and the position and size of the recess is considered to provide low order mode selection.