Semiconductor Laser Waveguide Width Modulation
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Solution Overview
Problem
Conventional semiconductor laser elements experience increased loss of both fundamental and higher order modes, leading to decreased beam quality, particularly as the ratio of fundamental mode decreases.
Innovation Solution
A semiconductor laser element with a waveguide whose width is modulated along its resonator length, featuring a first waveguide with a smaller width and a second waveguide that is wider, along with a dielectric layer with a lower refractive index than the second semiconductor layer, to reduce fundamental mode loss and enhance beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rough surface optical waveguide mechanism is used to reduce higher order mode loss, then the proportion of fundamental mode increases, but the loss of fundamental mode also increases
Solution Approach 1:
The waveguide width is varied locally along the resonator length, creating regions with different widths (wider and narrower portions) that perform different functions. The wider portions support both fundamental and higher order modes, while the narrower portions selectively filter higher order modes, achieving local optimization of mode control without excessive fundamental mode loss.
Solution Approach 2:
The waveguide structure transitions from a static uniform width to a dynamic varying width along the resonator length. This dynamic geometric modulation allows the waveguide to adapt its mode-selective properties at different positions, enabling selective loss of higher order modes while preserving fundamental mode propagation.
2Power
If a wide stripe waveguide is used to achieve high output power, then output power increases, but higher order modes are excited reducing beam quality
Solution Approach 1:
The waveguide is segmented into different width regions along the resonator length. The wider segments provide sufficient width for high power operation and support multiple modes, while the narrower segments act as mode filters that selectively attenuate higher order modes. This segmentation allows the system to achieve both high output power and good beam quality simultaneously.
Solution Approach 2:
The waveguide width parameter is changed along the resonator length rather than remaining constant. By modulating the width parameter, the waveguide can accommodate high power requirements in wider regions while using narrower regions to control the transverse mode distribution, achieving both high power and fundamental mode operation.
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 reduces the loss of the fundamental mode and increases its proportion, resulting in a semiconductor laser element with improved beam quality and high output power.
Implementation Method 1
a difference between an effective index of refraction inside the waveguide and an effective index of refraction outside the waveguide is greater at the second waveguide than at the first waveguide
Data Source
AI summary
A semiconductor laser element is a semiconductor laser element that emits laser light, and the semiconductor laser element includes a substrate, a first semiconductor layer above the substrate, a light emitting layer above the first semiconductor layer, a second semiconductor layer above the light emitting layer, and a dielectric layer above the second semiconductor layer. The second semiconductor layer includes a waveguide that guides the laser light. A width of at least a portion of the waveguide is modulated with respect to a position in a direction of resonator length, the direction being a longitudinal direction of the waveguide. The waveguide includes a first waveguide and a second waveguide that is wider than the first waveguide. A difference between an effective index of refraction inside the waveguide and an effective index of refraction outside the waveguide is greater in the second waveguide than in the first waveguide.