In-Fiber Offset to Annulus Converter for Beam Quality
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Solution Overview
Problem
In high power variable or multi-state beam shaping applications, existing techniques for displacing a beam into a separate region of a waveguide via an offset lead to a significant increase in the beam parameter product (BPP), degrading beam quality due to an abrupt change in beam radius without corresponding decrease in divergence.
Innovation Solution
An all-fiber technique that converts an offset-shaped beam into a ring-shaped or partial ring-shaped beam via an azimuthally tapered transition, maintaining a lower BPP by gradually increasing the effective beam radius while decreasing divergence, thus minimizing the increase in BPP and preserving beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If an offset beam is abruptly converted to a larger beam radius without corresponding decrease in divergence, then the beam radius increases to fill the outer core, but the beam parameter product significantly increases degrading beam quality
Solution Approach 1:
The beam guiding region is designed with a dynamic, gradually expanding geometry that transitions the beam from an offset configuration to a concentric annular configuration. This gradual expansion allows the beam radius to increase while the divergence simultaneously decreases, maintaining a constant beam parameter product and preserving beam quality throughout the transition.
Solution Approach 2:
The patent changes the geometric parameters of the beam guiding region along its length, creating a rotationally expanding profile that transforms the beam shape. This parameter change enables the beam to evolve from a small offset beam to a larger annular beam while conserving the beam parameter product through controlled modification of the guiding region's cross-sectional geometry.
2Area of moving object
If non-ideal optics are used to increase beam radius, then the beam radius increases, but the beam parameter product significantly increases spoiling beam quality
Solution Approach 1:
The beam guiding region acts as an intermediary structure between the input offset beam and the output annular beam. This intermediary gradually transforms the beam geometry through its rotationally expanding profile, avoiding the need for non-ideal optics that would abruptly change beam radius and degrade beam quality.
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 enables lower BPP states, resulting in higher beam quality and improved focusing capabilities for high power beams by maintaining a constant beam parameter product during the transition from an offset to a ring-shaped or partial ring-shaped beam.
Implementation Method 1
a waveguide that includes a rotationally expanding beam guiding region to conserve a beam parameter product associated with an offset beam that is gradually converted to an annulus or ring-shaped beam
Data Source
AI summary
In some implementations, a waveguide may comprise an inner core to receive a first beam and an outer core surrounding the inner core to receive a second beam that is displaced from the first beam by an offset. The outer core may comprise a beam guiding region that rotationally expands over a length of the waveguide into an annulus that concentrically surrounds the inner core or a partial annulus that partially surrounds the inner core. For example, the beam guiding region may be defined by one or more low refractive index features that have a varied orientation and/or a varied shape over the length of the waveguide such that the second beam enters the waveguide as an offset beam and exits from the waveguide as a ring-shaped beam or a partial ring-shaped beam.