Prism-Based Wavelength Beam Combining for Laser Quality
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Solution Overview
Problem
Wavelength beam combining (WBC) laser systems face challenges in achieving high beam quality due to differences in beam sizes and angles of incidence on the diffraction grating, leading to reduced feedback uniformity and efficiency, as well as limited wavelength bandwidth.
Innovation Solution
Incorporating one or more prisms in the WBC resonator to collimate and converge beams to a common focal plane, reducing beam size differences and narrowing the wavelength bandwidth, while also providing a compact and robust design by supporting the fragile diffraction grating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple emitters are combined using a diffraction grating in a WBC system, then the output power and brightness are scaled up, but the beam quality deteriorates significantly due to different incident angles causing different projected beam sizes and incomplete beam overlap
Solution Approach 1:
A telescope optical system is introduced as an intermediary component between the emitters and the diffraction grating. This telescope system transforms the divergent beams from multiple emitters into parallel beams with uniform sizes before they reach the grating, ensuring complete beam overlap and maintaining high beam quality while combining multiple high-power emitters
Solution Approach 2:
The optical parameters of the beams are transformed by the telescope system. The beam sizes are standardized to be substantially equal, and the incident angles are adjusted to ensure uniform projection on the grating. This parameter standardization allows multiple emitters to be combined without degrading beam quality
2Adaptability or versatility
If a diffraction grating is used to combine beams from emitters at different wavelengths, then wavelength beam combining is achieved, but the wavelength bandwidth requirement increases, limiting the number of combinable emitters
Solution Approach 1:
The telescope optical system changes the angular parameters of the incident beams, transforming them into parallel beams with standardized sizes. This parameter transformation reduces the effective wavelength bandwidth requirement of the system, allowing more emitters at different wavelengths to be combined within the available bandwidth
3Productivity
If emitters operate at different wavelengths to enable wavelength beam combining, then the wavelength bandwidth resource is consumed, but this limits the dispersion power and defines the maximum number of combinable emitters
Solution Approach 1:
By transforming the beam parameters through the telescope system, the effective use of wavelength bandwidth is optimized. The standardized beam sizes and parallel propagation reduce the bandwidth consumption per emitter, thereby increasing the maximum number of emitters that can be combined within the available wavelength bandwidth
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 use of prisms improves beam quality and laser performance by minimizing beam size differences and reducing wavelength bandwidth, enhancing feedback uniformity and efficiency, and allowing for a more compact resonator design.
Implementation Method 1
The one or more prisms are disposed optically downstream of the focusing optics and optically upstream of the diffraction grating. The one or more first prisms receive the beams on an entrance surface of one of the first prisms at an angle of incidence and transmit the beams from an exit surface of one of the first prisms to the diffraction grating at an exit angle
Implementation Method 2
The diffraction grating receives and disperses the focused beams
Implementation Method 3
The partially reflective output coupler receives the dispersed beams, transmits a portion of the dispersed beams therethrough as a multi-wavelength output beam, and reflects a second portion of the dispersed beams back toward the beam emitter
Data Source
AI summary
In various embodiments, one or more prisms are utilized in a wavelength beam combining laser system to regulate beam size and/or to provide narrower wavelength bandwidth.