Gradient Index Waveguide Vertical Mode Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in optical mode conversion and vertical displacement between semiconductor optical waveguides and optical fibers is hindered by the complexity and cost of existing solutions, such as waveguide tapers, which occupy significant space on photonic chips and are difficult to implement.
Innovation Solution
A semiconductor optical waveguide device is manufactured using a gradient index waveguide with a transversal bell-shaped refractive index profile, combined with step index waveguides, to form an optical path that enables efficient mode size conversion and vertical displacement, achieved through epitaxial growth and recess formation, allowing for a compact and reproducible design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If waveguide tapers are used for mode size conversion, then optical mode transformation is achieved, but the device occupies considerable area on photonic chip
Solution Approach 1:
The patent transitions from planar 2D waveguide mode conversion to 3D vertical mode conversion using stacked waveguide layers. The gradient index waveguide is formed in a vertical recess, enabling mode size transformation along the vertical dimension rather than requiring long horizontal tapers, thus reducing the horizontal footprint on the photonic chip.
Solution Approach 2:
The patent employs a gradient index profile where the refractive index varies continuously in the vertical direction. This parameter change enables adiabatic mode transformation between different mode sizes without requiring long interaction lengths, achieving compact mode conversion by controlling the refractive index distribution rather than relying on geometric tapering.
2Reliability
If waveguide tapers are used for mode conversion, then optical coupling is achieved, but the implementation is costly and difficult in production environment
Solution Approach 1:
The gradient index waveguide is formed by controlling the composition gradient during epitaxial growth, specifically varying the indium content in InGaAsP layers. This parameter control during a standard semiconductor fabrication process enables precise refractive index profiling without requiring complex post-processing or specialized equipment, making the solution manufacturable and reproducible.
Solution Approach 2:
The patent replaces the mechanical/geometric approach of physical waveguide tapers with a material-based gradient index structure. Instead of mechanically varying the waveguide geometry, the refractive index is varied through compositional gradient in the semiconductor material, enabling mode conversion through material properties rather than structural shaping.
3Reliability
If vertical couplers are used for mode conversion, then optical coupling between waveguides is achieved, but the device complexity increases
Solution Approach 1:
The patent combines the mode conversion function and the optical coupling function into a single gradient index waveguide structure. The same vertical waveguide with gradient index profile simultaneously performs both mode size transformation and vertical displacement, eliminating the need for separate vertical coupler components and reducing overall device complexity.
Solution Approach 2:
The gradient index waveguide serves multiple functions: it performs mode size conversion, vertical displacement, and optical coupling between different waveguide layers. This multi-functional design eliminates the need for separate specialized components for each function, simplifying the overall device architecture.
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 results in a significantly reduced physical size of the optical waveguide device, enabling efficient mode size transformation and vertical displacement with minimal optical losses, suitable for integration with photonic integrated circuits and optical fibers.
Implementation Method 1
a gradient index waveguide comprising a local refractive index depending on a growth parameter, wherein the growing comprises varying the growth parameter so as to gradually increase the local refractive index to a maximum value, and then to gradually decrease the local refractive index
Implementation Method 2
growing on a substrate a base waveguide comprising one of: i) a gradient index waveguide... wherein the growing comprises varying the growth parameter
Data Source
AI summary
A semiconductor waveguide optical device and a method of manufacturing of a semiconductor optical device are disclosed. The semiconductor waveguide optical device may include a gradient index waveguide for mode conversion and/or vertical translation of optical modes of step-index waveguides, which may be disposed on or over a same substrate as the gradient index waveguide. The gradient index waveguide may be epitaxially grown.