Semiconductor Optical Gain Structure With Reflective Grating Coupling
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Solution Overview
Problem
The InP substrate in existing integrated grating coupler systems has the largest thickness variation, leading to variations in light emission position and necessitating high mounting accuracy for the first optical chip on the second optical chip, which affects coupling efficiency.
Innovation Solution
A semiconductor optical gain device with a substrate, active portion, and passive portion, featuring a first grating coupler and a reflection portion with at least one air layer to reflect diffraction light, reducing positional variation and improving coupling efficiency by using a distributed Bragg reflector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the InP substrate thickness is increased to improve light emission, then the thickness variation increases, causing light emission position variation and requiring higher mounting accuracy
Solution Approach 1:
The patent introduces a reflection portion as an intermediary element between the InP substrate and the first grating coupler. This reflection portion compensates for thickness variations in the InP substrate by reflecting light that would otherwise be lost due to positional variations, thereby maintaining stable light emission without requiring high mounting accuracy.
Solution Approach 2:
The patent changes the optical path parameters by introducing a reflection mechanism that alters the direction and position of light emission. By modifying how light propagates and is emitted from the device, the system becomes insensitive to substrate thickness variations, resolving the contradiction between light emission quality and manufacturing precision requirements.
2Reliability
If the mounting accuracy is improved to compensate for light emission position variation, then the coupling efficiency improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The reflection portion serves as a compensatory intermediary that actively corrects for misalignment caused by substrate thickness variations. Instead of relying on precise mounting, the reflection portion redirects light to ensure proper coupling, thereby maintaining high reliability without increasing device complexity or mounting difficulty.
Solution Approach 2:
The patent implements a beforehand cushioning mechanism by pre-designing the reflection portion to compensate for expected thickness variations in the InP substrate. This proactive compensation ensures that even if mounting accuracy is not perfect, the coupling efficiency remains high, effectively cushioning against manufacturing tolerances.
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
The solution reduces positional variation of emitted light and enhances mounting accuracy and coupling efficiency between the semiconductor optical gain device and the optical waveguide chip.
Implementation Method 1
The first grating coupler diffracts light output from the active layer to generate a first diffraction light traveling from the first grating coupler toward the top surface and a second diffraction light traveling from the first grating coupler toward the substrate
Implementation Method 2
The reflection portion is disposed between the first grating coupler and the substrate to reflect the second diffraction light toward the top surface of the passive portion
Data Source
AI summary
A semiconductor optical gain device includes a substrate, an active portion, and a passive portion. The active portion includes an active layer. The passive portion includes a first core layer, a reflection portion, and a top surface. The first core layer is formed with a first grating coupler. The first grating coupler diffracts light output from the active layer to generate a first diffraction light and a second diffraction light. The reflection portion is disposed between the first grating coupler and the substrate to reflect the second diffraction light toward the top surface of the passive portion, and includes at least one air layer.