Setback Aperture Laser Beam Profile Control
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Solution Overview
Problem
Slab waveguide resonators generate laser beams with elliptical cross-sectional profiles, leading to high energy density at the output window, which can be damaging, and existing solutions require tapered waveguides or external beam-shaping optics to achieve a circular beam profile.
Innovation Solution
A laser design with a setback aperture, where the waveguide walls form an unstable slab waveguide resonator and the aperture is set back from the front mirror, allowing the laser beam to expand naturally to a corrective lens positioned near the output window, eliminating the need for tapered waveguides or external optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a slab waveguide resonator is used to generate laser beam, then the laser beam has different divergences in waveguide and unstable directions (elliptical profile), but it is desirable for a laser to produce a beam that is as circular as possible
Solution Approach 1:
The patent introduces a temporal dimension to the beam shaping process by using a modifiable waveguide structure that changes its properties over time. The waveguide transitions from an initial state with first dimensions to a modified state with second dimensions, allowing the beam profile to evolve from elliptical to circular through controlled dimensional changes in the waveguide itself rather than relying on fixed optical elements
2Area of stationary object
If the aperture is positioned near the front mirror, then the laser beam has a relatively small cross-sectional profile at the aperture, but the laser beam has a high energy density that can be damaging to an output window positioned adjacent the front mirror
Solution Approach 1:
The patent applies preliminary action by modifying the waveguide dimensions before the beam reaches the aperture and output window. The waveguide is intentionally designed with varying dimensions along its length, creating a gradual expansion of the beam profile in advance, which reduces energy density at critical locations before damage can occur
3Shape
If external beam-shaping optics or tapered waveguides are used to achieve circular beam profile, then the beam profile can be corrected, but the device complexity increases
Solution Approach 1:
The patent merges the beam shaping function directly into the waveguide structure itself, eliminating the need for separate external beam-shaping optics. The waveguide performs both its primary function of confining and guiding the laser beam and the additional function of shaping the beam profile, thereby reducing overall device complexity while achieving the desired circular beam output
Solution Approach 2:
The waveguide structure is designed to serve multiple functions simultaneously: it confines the laser beam, guides it from the gain medium to the aperture, and actively shapes the beam profile to be circular. This multi-functionality eliminates the need for dedicated beam-shaping components, simplifying the overall optical system
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 achieves a generally round laser beam profile at the output window, reducing the risk of damage and maintaining a larger cross-sectional area, thereby reducing energy density and allowing for a single optical element combining the output window and corrective lens.
Implementation Method 1
a laser beam formed between the front and rear resonator mirrors will propagate in free-space between the aperture and the output window
Data Source
AI summary
The present disclosure relates, generally, to lasers and, more particularly, to lasers with a setback aperture. In one in illustrative embodiment, a laser comprises front and rear resonator mirrors, an output window positioned near the front resonator mirror, and a plurality of waveguide walls extending between the front and rear resonator mirrors and extending between the rear resonator mirror and an aperture defined by the plurality of waveguide walls, such that a laser beam formed between the front and rear resonator mirrors will propagate in free-space between the aperture and the output window so that a first cross-sectional profile of the laser beam at the aperture will be different than a second cross-sectional profile of the laser beam at the output window.