Edge-Emitting Semiconductor Light Source With APC Feedback
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in maintaining constant light output due to temperature variations, particularly with edge light emitting elements, where the light output decreases with increasing temperature, and existing solutions do not effectively address this issue efficiently.
Innovation Solution
The semiconductor light emitting device incorporates a substrate with ceramic materials for heat dissipation, an edge light emitting element configured to emit laser beams from multiple end surfaces, and a light receiving element mounted on a sub-mount to directly receive the laser beams, allowing for efficient APC drive to maintain constant output by controlling the drive current based on the light receiving element's output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If edge light emitting elements are used to emit laser beams, then light output intensity is improved, but temperature variations cause light output to decrease
Solution Approach 1:
The patent implements automatic power control (APC) by using a light receiving element to detect the light output from the edge light emitting element and feed back a signal to adjust the drive current. This feedback mechanism compensates for temperature-induced output variations, maintaining stable light output despite temperature changes.
Solution Approach 2:
The patent changes the drive current parameter dynamically based on temperature conditions and light output detection. By adjusting the drive current in response to temperature variations, the system compensates for the decrease in light output intensity, resolving the contradiction between maintaining high output and ensuring output stability.
2Reliability
If APC drive is implemented to maintain constant output, then output stability is improved, but device complexity increases
Solution Approach 1:
The patent combines the light receiving element, sub-mount, and control circuitry into an integrated assembly. The light receiving element is mounted on the sub-mount in close proximity to the edge light emitting element, merging multiple functions (light detection, mounting, and control) into a compact integrated structure, thereby reducing overall system complexity while maintaining APC functionality.
Solution Approach 2:
The sub-mount serves multiple functions: it provides mechanical support for the light receiving element, facilitates heat dissipation, and enables the APC control mechanism. This multi-functionality reduces the need for separate components, simplifying the overall device structure while maintaining output stability.
3Measurement precision
If light receiving element is mounted on sub-mount to directly receive laser beams, then light detection efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The light receiving element is pre-mounted on the sub-mount with predetermined positioning features before final assembly. The sub-mount includes predefined mounting structures that ensure correct alignment when the assembly is installed, performing the alignment action in advance during manufacturing rather than requiring high precision during final assembly.
Solution Approach 2:
The system is divided into separate modules: the edge light emitting element, the light receiving element mounted on the sub-mount, and the control circuitry. This segmentation allows each module to be manufactured and tested independently with relaxed precision requirements, then assembled together to achieve the required overall performance.
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 ensures a constant light output by efficiently receiving and managing the laser beams from the edge light emitting element, effectively addressing temperature-related output variations and maintaining device performance.
Implementation Method 1
a light receiving element (40) mounted on the light receiving sub-mount (70) and configured to receive the second laser beam (L2)
Implementation Method 2
Current semiconductor light emitting devices face challenges in maintaining constant light output due to temperature variations
Data Source
AI summary
A semiconductor light emitting device includes: a substrate including a substrate front surface; an edge light emitting element mounted on the substrate front surface, the edge light emitting element including a first element end surface facing a first direction intersecting a thickness direction perpendicular to the substrate front surface and a second element end surface facing an opposite direction to the first element end surface, the edge light emitting element configured such that light is emitted from the first element end surface and the second element end surface; a light receiving sub-mount provided over the substrate front surface and including a mounting surface facing the second element end surface; and a light receiving element mounted on the mounting surface and including a light receiving portion provided at a light receiving element front surface and facing the second element end surface.