Semiconductor Laser Wavelength Diversification for Interference Suppression
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Solution Overview
Problem
Current semiconductor laser devices for display applications, particularly in augmented and virtual reality, face challenges in achieving high image quality due to interference from laser beams with the same wavelength, leading to degraded image quality, and require complex and costly drive circuits for short pulse width modulation to broaden spectral width.
Innovation Solution
A semiconductor laser device with multiple light-emitting sections emitting laser beams in the red range, where the difference in peak wavelengths between at least one laser beam and others is 1.5 nm or more, allowing for improved image quality without the need for high-frequency superimposition and dedicated drive circuits, by varying the width, thickness, and composition ratio of the light-emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple laser beams with the same wavelength are used for each RGB color, then the color gamut and resolution are improved, but interference fringes appear in the waveguide causing image quality degradation
Solution Approach 1:
The patent applies parameter changes by setting the wavelength difference between adjacent laser beams to 1.5 nm or more. This specific parameter adjustment prevents constructive interference that causes fringes while maintaining the multi-beam configuration for high resolution and color gamut. The wavelength parameter is optimized to balance image quality with the need for multiple beams.
2Reliability
If transverse single-mode LDs with monolithic structure are used to independently drive multi-emitters at narrow pitch, then the beam quality is improved, but the wavelength spectrum becomes narrow and interference increases
Solution Approach 1:
The patent resolves this contradiction by changing the wavelength parameter, ensuring a difference of 1.5 nm or more between adjacent beams. This allows the use of transverse single-mode LDs with narrow pitch for high beam quality while preventing interference through wavelength diversification.
3Object-generated harmful factors
If high-frequency superimposition with pulse width of 15 ns or less is applied to broaden spectral width, then the interference is suppressed, but a dedicated drive circuit is required significantly increasing cost
Solution Approach 1:
The patent changes the wavelength parameter directly in the laser beam generation process, achieving interference suppression without requiring complex high-frequency drive circuits. This parameter-based solution eliminates the need for dedicated drive circuitry while maintaining effective interference suppression.
4Measurement precision
If pulse width of 15 ns or less is used to expand full width at half maximum, then the spectral width is broadened to prevent fringing, but the drive circuit becomes technically challenging and costly
Solution Approach 1:
The patent achieves spectral width expansion through wavelength parameter changes in the laser source itself, rather than through pulse width modulation. This approach broadens the spectrum to prevent fringing while avoiding the need for complex short-pulse drive circuits.
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 enhances visual sensitivity and image quality by reducing interference fringes and simplifying the system configuration, while maintaining high temperature operation and brightness, without the complexity and cost of high-frequency drive circuits.
Implementation Method 1
a light-emitting layer that is formed between the first cladding layer and the second cladding layer, and is formed on a first surface parallel to the main surface of the substrate; the light-emitting layer has a plurality of light-emitting sections emitting laser beams in a red range
Data Source
AI summary
A semiconductor laser device includes: a substrate having a main surface; a first cladding layer with a first conductive type and a second cladding layer with a second conductive type, which are stacked over the main surface of the substrate; and a light-emitting layer that is formed between the first cladding layer and the second cladding layer, and is formed on a first surface parallel to the main surface of the substrate; the light-emitting layer has a plurality of light-emitting regions emitting laser beams in a red range; and among the laser beams emitted from the light-emitting regions, the difference between a peak wavelength in an optical spectrum of at least one laser beam and a peak wavelength in an optical spectrum of the other laser beams is 1.5 nm or more.