Surface-Emitting Laser Resonator for Optical Damage Reduction
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Solution Overview
Problem
Laser devices face optical damage issues on the light emitting surface of the gain medium due to high light density and heat concentration, particularly in high-power applications like cutting and drilling, where existing technologies do not effectively disperse light density across the emitting surface.
Innovation Solution
A laser device configuration featuring a semiconductor gain medium with a varying gain distribution and an antireflection film, combined with a diffraction grating and optical elements, which disperses light density across the emitting surface, reducing optical damage and heat concentration by using a surface emitting light source without waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-power laser beam is emitted using conventional gain medium configurations, then the output power is increased, but optical damage to the light emitting surface occurs due to high light density and heat concentration
Solution Approach 1:
The gain medium is designed with a non-uniform gain distribution across its surface, creating different optical properties in different regions. This allows the light density to be distributed more evenly across the light emitting surface, preventing localized overheating and optical damage while maintaining high overall output power.
Solution Approach 2:
The patent transitions from conventional point or line source configurations to a surface emitting light source configuration. By emitting laser light from an extended surface area rather than a concentrated point, the light density is distributed across two dimensions, significantly reducing the intensity at any single location and preventing optical damage.
2Speed
If a waveguide structure is used in the gain medium, then light confinement and directionality are improved, but heat concentration and optical damage risk increase
Solution Approach 1:
The waveguide structure is completely removed from the gain medium configuration. Instead of confining light through waveguide walls that concentrate energy, the patent uses a surface emitting approach where light is generated and emitted directly from the gain medium surface, eliminating the heat concentration problem associated with waveguide structures while maintaining adequate light directionality through the resonator geometry.
3Reliability
If the light emitting surface area is increased to reduce light density, then optical damage is reduced, but the device complexity increases
Solution Approach 1:
The gain medium itself is designed to provide the light density distribution function through its inherent non-uniform gain profile. The structure serves multiple functions simultaneously: it generates light, controls its spatial distribution, and prevents optical damage, eliminating the need for additional complex optical elements or structures that would otherwise be required.
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 effectively reduces optical damage and heat concentration on the light emitting surface, enhancing the durability and performance of the laser device while maintaining high output power, suitable for applications like metal processing and 3D printing.
Implementation Method 1
a wavelength beam combining (WBC) technique is known, in which a plurality of laser beams having different wavelengths are coaxially combined with each other by a diffraction grating
Implementation Method 2
an antireflection film provided on the light emitting surface of the gain medium
Data Source
AI summary
The laser device includes a first mirror and a second mirror forming a resonator, a gain medium disposed between the first mirror and the second mirror and having a light emitting surface, an antireflection film provided on the light emitting surface of the gain medium, at least one optical element disposed between the gain medium and the second mirror, and a diffraction grating disposed between the optical element and the second mirror. The gain medium is a semiconductor layered body including an active layer and having a varying gain distribution in at least a first direction within the light emitting surface, and includes no waveguide.