Planar Waveguide Laser with Hybrid Spatial Filter
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Solution Overview
Problem
Current high-pulse energy, high-peak power lasers operating at eye-safe wavelengths with diffraction-limited performance do not exist, as existing technologies face limitations in achieving both high pulse energies and beam qualities efficiently, with fiber lasers restricted to low pulse energies and bulk solid state lasers unable to operate at eye-safe wavelengths.
Innovation Solution
A system utilizing a planar waveguide with an active gain medium and a hybrid spatial filter, including a physical slit and Volume Bragg Grating, configured to operate in single mode in the fast axis and multimode in the slow axis, which reduces intensity and constrains the angle of amplified stimulated emission light, enabling the generation of high-pulse energy, high-peak power lasers with diffraction-limited performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fiber lasers are used to operate at eye-safe wavelengths, then wavelength safety is improved, but pulse energy is limited to low levels
Solution Approach 1:
The system segments the laser cavity into distinct functional regions: a planar waveguide section for high-energy lasing and a fiber spatial filter section for beam quality control. This segmentation allows the laser to achieve both high pulse energy from the bulk waveguide and diffraction-limited beam quality through the fiber-based spatial filtering, resolving the contradiction between eye-safe operation and high pulse energy capability
Solution Approach 2:
The system merges the advantages of bulk solid-state lasers (high pulse energy, eye-safe wavelength operation) with fiber lasers (diffraction-limited beam quality, spatial mode control) into a hybrid architecture. The planar waveguide provides high-energy lasing while the fiber spatial filter imposes single-mode constraints, combining both approaches to achieve simultaneously high pulse energy and beam quality
2Quantity of substance
If bulk solid state lasers are used to achieve high pulse energies, then pulse energy is improved, but eye-safe wavelength operation is not achieved
Solution Approach 1:
The system changes the wavelength parameter by using erbium-doped planar waveguide that lases at 1.5-1.6 micrometers, which is in the eye-safe wavelength region. This parameter change allows the bulk solid-state laser to operate at wavelengths that do not damage the retina, while maintaining high pulse energy capability through the planar waveguide geometry
3Power
If high-pulse energy lasers are optimized for high power and efficiency, then power and efficiency are improved, but beam quality deteriorates
Solution Approach 1:
The fiber spatial filter acts as an intermediary element between the high-power planar waveguide laser and the output beam. It imposes single-mode spatial constraints on the beam without significantly reducing the pulse energy, thereby improving beam quality while maintaining the high power and efficiency characteristics of the bulk laser medium
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 solution achieves ultra-high pulse energies and peak powers with high average power performance in a compact size and weight footprint, maintaining near diffraction-limited beam quality, suitable for applications like eye-safe illuminator lasers and military tracking lasers.
Implementation Method 1
an active gain medium configured to receive pump light from a pump source and amplify stimulated emission light
Implementation Method 2
The physical slit is configured to reduce an intensity of the amplified stimulated emission light received from the planar waveguide
Implementation Method 3
a Volume Bragg Grating (VBG) configured to constrain an angle of the amplified stimulated emission light
Implementation Method 4
a planar waveguide that includes an active gain medium configured to receive pump light from a pump source and amplify stimulated emission light
Data Source
AI summary
A system includes a planar waveguide that includes an active gain medium configured to receive pump light from a pump source and amplify stimulated emission light. The planar waveguide has a fast axis and a slow axis and is configured to operate in single mode in the fast axis and multimode in the slow axis. The system also includes a hybrid spatial filter configured to receive the amplified stimulated emission light from the planar waveguide and output laser light. The hybrid spatial filter includes a physical slit having a narrower dimension corresponding to the slow axis of the planar waveguide. The physical slit is configured to reduce an intensity of the amplified stimulated emission light received from the planar waveguide. The hybrid spatial filter also includes a Volume Bragg Grating (VBG) configured to constrain an angle of the amplified stimulated emission light and enable compact geometry intra-cavity beam expanding/collimating optics.