Optical Semiconductor Device Asymmetric Rear Surface Tilt
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Solution Overview
Problem
Existing optical semiconductor devices face issues with rear-end-surface-side emergent light striking the mount substrate due to increased surface area requirements, leading to reduced optical output and increased noise from stray light reflections.
Innovation Solution
The optical semiconductor device design features a semiconductor laser that emits rear-end-surface-side emergent light with an optical axis extending away from the mount substrate, preventing light from striking the substrate and allowing for efficient monitoring and reduced noise through the use of an inclined mount substrate and optimized photodiode placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mount substrate surface area is increased to accommodate wiring patterns for connection between the semiconductor laser and lead pins, then the electrical connection is improved, but the emergent light with angular divergence easily strikes the mount substrate causing reduced optical output and increased noise
Solution Approach 1:
The patent applies asymmetry by tilting the rear end surface of the semiconductor laser at a specific angle (e.g., 10-20 degrees) relative to the mount substrate. This asymmetric configuration causes the rear-end-surface-side emergent light to be directed away from the mount substrate, preventing light from striking the substrate while maintaining electrical connections through the wiring pattern on the mount substrate.
Solution Approach 2:
The patent introduces a dimensional change by tilting the rear end surface of the semiconductor laser, transforming the light emission direction from a planar configuration to a three-dimensional angled configuration. This dimensional adjustment redirects the emergent light away from the mount substrate in the vertical dimension while preserving the horizontal wiring connections.
2Area of stationary object
If the mount substrate surface area is increased, then the wiring pattern can be accommodated, but the optical output is reduced due to light striking the substrate
Solution Approach 1:
By tilting the rear end surface of the semiconductor laser asymmetrically, the patent enables the use of a larger mount substrate surface area for accommodating wiring patterns without suffering from the harmful effect of light striking the substrate. The asymmetric tilt redirects light away from the substrate, preserving optical output while allowing increased substrate area for electrical connections.
3Area of stationary object
If the mount substrate surface area is increased, then the wiring pattern can be accommodated, but noise increases due to stray light reflections
Solution Approach 1:
The asymmetric tilt of the rear end surface of the semiconductor laser prevents emergent light from striking the mount substrate, thereby eliminating stray light reflections that would generate noise. This allows the mount substrate surface area to be increased for wiring accommodation without the penalty of increased noise from light reflections.
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 design ensures high optical output and reduced noise by preventing emergent light from striking the mount substrate, even with increased substrate size, while maintaining accurate monitoring and controllability.
Implementation Method 1
a semiconductor laser which emits front-end-surface-side emergent light on a front end surface side and emits rear-end-surface-side emergent light on a rear end surface side
Implementation Method 2
an optical semiconductor device that receives emergent light from a rear end surface of a semiconductor laser by a photodiode
Data Source
AI summary
An optical semiconductor device has a semiconductor laser which emits front-end-surface-side emergent light on the front end surface side and emits rear-end-surface-side emergent light on the rear end surface side, and a mount substrate having the semiconductor laser provided on its front surface. The rear-end-surface-side emergent light is emitted while having an emergence optical axis that extends away from the mount substrate with increase in distance from the rear end surface.