Optical Mode Convertor for Low-Loss Silicon Waveguide Transitions
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Solution Overview
Problem
Photonics chips face significant optical power loss when transitioning from a silicon waveguide of one thickness to another, limiting integration of optical sources and modulators on a single die with a buried oxide layer.
Innovation Solution
An optical mode convertor with three stages - input, transition, and output - featuring varying Si slab and waveguide heights, allowing for low-loss mode transformation on a 1 micrometer-thick BOX layer, enabling integration of optical sources and modulators with reduced footprint and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a direct transition is made from a silicon waveguide of one thickness to another thickness, then the waveguide thickness can be changed to enable integration of optical sources and modulators, but significant optical power loss occurs
Solution Approach 1:
The waveguide thickness transition is divided into three distinct stages: input stage, transition stage, and output stage. Each stage has specific thickness configurations (input: 400nm/200nm, transition: 200nm/150nm, output: 200nm/150nm) that progressively transform the optical mode, avoiding abrupt changes that cause high loss
Solution Approach 2:
The transition stage acts as an intermediary between the input and output stages, with intermediate thickness values (200nm Si waveguide height, 150nm Si slab height) that gradually bridge the gap between the input waveguide dimensions and the desired output dimensions, enabling low-loss mode transformation
2Ease of manufacture
If a thicker BOX layer is used in legacy photonic circuits, then manufacturing is simplified, but the footprint and placement flexibility are reduced
Solution Approach 1:
The patent specifies a BOX layer thickness of approximately 1 micrometer, which is thinner than legacy circuits but optimized for the three-stage mode conversion architecture. This parameter change enables both low-loss operation and reduced footprint while maintaining manufacturability through standard semiconductor processes
3Reliability
If different waveguide thicknesses are used for optical sources and modulators, then each component can operate optimally, but the transition between them causes high optical loss
Solution Approach 1:
The waveguide dimensions are made dynamic along the propagation direction, with the Si waveguide height changing from 400nm at the input stage to 200nm at the transition stage, and the Si slab height changing from 200nm to 150nm. This dynamic variation allows the optical mode to adapt continuously, minimizing loss while enabling different thicknesses for optimal source and modulator 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
The optical mode convertor achieves very low optical losses, approximately 0.08 decibels, facilitating efficient integration of optical components with improved operational characteristics and reduced power requirements.
Implementation Method 1
an optical mode convertor configured to transition the optical mode of light propagating through the Si waveguide
Data Source
AI summary
Embodiments relate to an apparatus that includes: an input stage with an input Si slab height, an input Si waveguide height, and an input height difference between the input Si slab height and the input Si waveguide height; an output stage with an output Si slab height that is different from the input Si slab height, an output Si waveguide height that is different from the input Si waveguide height, and an output height difference between the output Si slab height and the output Si waveguide height that is different from the input height difference; and a transition stage positioned between the input stage and the output stage, wherein the transition stage has a transition Si slab height, a transition Si waveguide height, and a transition height difference between the transition Si slab height and the transition Si waveguide height. Other embodiments may be described and/or claimed.