Semiconductor Laser Stripe Structure for High Output
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Solution Overview
Problem
Current semiconductor laser devices for optical disc systems face challenges in achieving high optical output while maintaining compact size and minimizing heat generation, noise, and thermal saturation, particularly when integrating lasers for red and infrared regions on a single substrate, which affects their efficiency and reliability for high-speed recording applications.
Innovation Solution
The semiconductor laser device incorporates a unique stripe structure with varying widths along the resonator direction for both the red and infrared light emitting portions, with specific relationships between the front and rear end face widths to optimize reflectance, reduce series resistance, and improve luminous efficiency, thereby achieving high optical output and low operation current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two separate laser packages (AlGaInP-based 650nm and AlGaAs-based 780nm) are integrated into an optical pickup, then the device can reproduce data from DVD and CD/MD, but the optical pickup size becomes large
Solution Approach 1:
The patent merges two separate laser devices (AlGaInP-based 650nm laser and AlGaAs-based 780nm laser) into a single integrated semiconductor laser device by forming both light-emitting portions on one GaAs substrate, thereby reducing the optical pickup size while maintaining compatibility with both DVD and CD/MD
2Power
If the stripe structure width is increased to reduce series resistance and improve luminous efficiency, then optical output increases, but heat generation and thermal saturation increase
Solution Approach 1:
The patent applies different stripe structure widths to different regions of the laser device: a first stripe structure with width W1 in the red light-emitting portion and a second stripe structure with width W2 in the infrared light-emitting portion, where W1 > W2. This local differentiation optimizes current distribution and heat dissipation in each region, allowing high optical output while managing heat generation effectively
Solution Approach 2:
The patent introduces asymmetric stripe structure widths between the red and infrared light-emitting portions, creating an optimized current density distribution that improves luminous efficiency while preventing thermal saturation in the high-power red laser region
3Temperature
If the stripe structure width is decreased to reduce heat generation, then thermal saturation is reduced, but series resistance increases and luminous efficiency decreases
Solution Approach 1:
The patent implements local quality optimization by assigning different stripe widths to different functional regions: the red light-emitting portion uses a wider stripe (W1) to maintain low series resistance and high luminous efficiency, while the infrared portion uses a narrower stripe (W2) to reduce heat generation, thereby achieving both goals simultaneously in their respective regions
4Ease of manufacture
If a constant stripe width is used throughout the resonator, then manufacturing is simplified, but optical output is limited due to thermal saturation in high-power regions
Solution Approach 1:
The patent applies local quality principle by varying the stripe structure width according to the specific requirements of each light-emitting portion: the red laser region uses width W1 optimized for high power output, while the infrared region uses width W2 optimized for thermal management, thereby achieving high optical output without significantly complicating the manufacturing process
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 approach enables a semiconductor laser device with high kink level, low operation current, and low operation voltage, suitable for high-output operations, while minimizing heat generation and maintaining compactness, thus enhancing the performance and efficiency of optical disc systems.
Implementation Method 1
with specific relationships between the front and rear end face widths to optimize reflectance, reduce series resistance, and improve luminous efficiency
Data Source
AI summary
The semiconductor laser device includes first and second light emitting portions each including a first cladding layer, an active layer and a second cladding layer, and each having a stripe structure. The stripe structure of the first light emitting portion has a section having a width changing along a resonator direction and includes a first front end face, and relationships of Wf1>=W1; W1>W2; and (Wf1-W1)/2L1<(W1-W2)/2L2 hold wherein Wf1 is a width on the first front end face; W1 is a width in a position away from the first front end face by a distance L1; and W2 is a width in a position away from said the front end face by a distance L1+L2 (whereas L1+L2<=L). The stripe structure of the second first light emitting portion has a section having a width changing along a resonator direction and includes a second front end face, and relationships of Wf2>=W3; W3>W4; and (Wf2-W3)/2L3<(W3-W4)/2L4 hold wherein Wf2 is a width on the second front end face; W1 is a width in a position away from the second front end face by a distance L3 (whereas L1<>L3); and W4 is a width in a position away from the second front end face by a distance L3+L4.