Semiconductor Optical Element Ridge Structure Stress Relief
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Solution Overview
Problem
Ridge-type semiconductor optical elements face issues with stress concentration on the optical confinement layer, leading to variations in characteristics and reliability concerns, which conventional stress adjustment methods fail to adequately address.
Innovation Solution
A semiconductor optical element design featuring a ridge structure with a wider intermediate layer than the bottom and top layers, configured to relieve stress and improve optical confinement and device resistance, including a diffraction grating layer and specific layer dimensions to optimize stress relief and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ridge-type waveguide structure is used for semiconductor optical elements, then the device can function as a laser light source or optical amplifier, but stress concentration occurs on the optical confinement layer and active layer causing slow variations in characteristics
Solution Approach 1:
The ridge structure is segmented into three distinct layers: ridge bottom layer, ridge intermediate layer, and ridge top layer. This segmentation allows each layer to serve specific functions - the bottom layer provides structural support, the intermediate layer relieves stress through its wider cross-section, and the top layer maintains optical confinement, thereby resolving the contradiction between functionality and reliability
Solution Approach 2:
The ridge intermediate layer is designed with an asymmetric cross-sectional width that is wider than both the ridge bottom layer and ridge top layer. This asymmetric configuration creates a stress-relief zone that prevents stress concentration on the optical confinement layer and active layer, eliminating characteristic variations while maintaining the waveguide's optical functionality
2Ease of manufacture
If the ridge structure is made with uniform width, then manufacturing is simplified, but stress concentration occurs on the buried portion and active layer
Solution Approach 1:
Instead of uniform width throughout the ridge structure, the patent applies local quality by making the ridge intermediate layer wider than the bottom and top layers. This localized width variation specifically addresses stress concentration in the critical region without complicating overall manufacturing, as the three-layer structure can still be fabricated using standard semiconductor processing techniques
3Reliability
If the ridge structure is designed to relieve stress, then characteristic variations are reduced, but the device complexity increases
Solution Approach 1:
The ridge is divided into three functional segments (bottom, intermediate, and top layers) with the intermediate layer serving the specific stress-relief function. This segmentation achieves reliable characteristic stability while keeping the overall structure manageable through clear functional differentiation, rather than requiring complex external stress-management mechanisms
Data Source
AI summary
A semiconductor optical element includes a first cladding layer; a second cladding layer formed in a ridge shape; and optical confinement layer interposed between the first cladding layer and the second cladding layer to propagate light, wherein the second cladding layer is configured with a ridge bottom layer; a ridge intermediate layer; and a ridge top layer in this order from the optical confinement layer, and the ridge intermediate layer is formed wider in cross section perpendicular to the optical axis—the light propagating direction in optical confinement layer—than the ridge bottom layer and the ridge top layer.