Oxide-Embedded Edge Coupler for Low-Loss Fiber Mode Matching
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Solution Overview
Problem
The manufacturing of optical waveguides faces challenges due to the large dimension mismatch between silicon waveguides and optical fibers, leading to significant optical signal loss during coupling, and existing methods struggle to efficiently convert optical modes to match the larger fiber dimensions.
Innovation Solution
A photonic structure with an edge coupler featuring an optical coupling region and a cladding layer, where the cladding layer includes an oxide structure embedded in the semiconductor substrate, which prevents optical signals from escaping and reduces signal loss by matching the optical mode of an external optical fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a waveguide taper is used to facilitate coupling between waveguide and optical fiber, then coupling efficiency is improved, but manufacturing complexity increases due to challenges in waveguide structure fabrication
Solution Approach 1:
The invention divides the waveguide structure into multiple functional segments: a standard waveguide portion and a separate waveguide taper portion. This segmentation allows each part to be optimized independently - the standard waveguide maintains simple fabrication while the taper portion specifically addresses coupling efficiency requirements.
Solution Approach 2:
The invention introduces a vertical dimension to solve the coupling problem by creating an elevated optical coupling region that extends above the substrate plane. This dimensional change enables mode field expansion and better fiber alignment without complicating the primary waveguide fabrication process.
2Reliability
If the optical coupling region is elevated above the substrate plane, then optical mode matching with fiber is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention introduces an intermediary support structure consisting of dielectric material and reflective layers that elevates the optical coupling region. This intermediary mechanism achieves the required elevation and optical mode matching while maintaining manufacturability through standard semiconductor fabrication processes.
Solution Approach 2:
The invention utilizes parameter changes in the dielectric material properties (refractive index, thickness) and reflective layer characteristics to control the optical field distribution and elevation. By adjusting these parameters, the system achieves optimal fiber coupling without requiring extreme manufacturing precision.
3Reliability
If oxide structure is embedded in semiconductor substrate, then optical signal confinement is improved, but process complexity increases for silicon-on-insulator substrates
Solution Approach 1:
The embedded oxide structure serves multiple functions simultaneously: it provides optical signal confinement through total internal reflection, acts as a support layer for the elevated coupling region, and serves as part of the fabrication process for silicon-on-insulator substrates. This multi-functionality reduces overall process complexity despite the added structural element.
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 oxide structure in the cladding layer effectively prevents optical signal loss by confining light within the waveguide, improving process stability and manufacturing yield, particularly for silicon-on-insulator substrates with thin buried oxide layers.
Implementation Method 1
an optical signal is confined in the waveguide structure by a total internal reflection from the waveguide walls
Data Source
AI summary
A photonic structure is provided. The photonic structure includes an oxide structure surrounded by a semiconductor substrate, a buried oxide layer over the semiconductor substrate, and an optical coupling region over the buried oxide layer. The oxide structure has a first side surface and a second side surface opposite to the first side surface. In a plan view, the optical coupling region is tapered from the first side surface of the oxide structure to the second side surface of the oxide structure.