Multi-Taper Optical Coupler for Low-Loss Waveguide-to-Fiber Interface
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Solution Overview
Problem
Conventional optical coupling techniques suffer from high energy loss due to mode-size and effective index mismatch, leading to inefficient signal transmission between optical devices such as fibers and waveguides, and are prone to damage.
Innovation Solution
A multi-taper optical coupler is introduced, featuring a plurality of tapers with taper-bases arranged in a first plane and taper-tips in a second plane, designed to convert propagation modes efficiently and provide a larger coupling area, reducing loss and increasing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a funnel coupler is used to increase coupling area, then the coupling area is enlarged, but energy loss increases due to mode-size and effective index mismatch
Solution Approach 1:
The coupler is divided into multiple discrete tapers (e.g., three tapers) arranged in parallel rather than using a single large funnel structure. Each taper independently contributes to coupling, collectively providing a large effective coupling area while maintaining low loss through individual adiabatic transitions.
Solution Approach 2:
The invention transitions from a two-dimensional funnel expansion to a three-dimensional multi-taper structure where tapers are arranged both laterally (providing area) and vertically (providing adiabatic transition). This dimensional arrangement allows simultaneous achievement of large coupling area and low loss.
2Loss of energy
If a single taper is used to reduce energy loss through adiabatic transition, then energy efficiency improves, but the coupling area becomes small and the tip is fragile
Solution Approach 1:
Multiple individual tapers are merged into a single integrated coupler structure. Each taper maintains its adiabatic transition properties for low loss, while their combination provides a collectively large coupling area and enhanced mechanical strength.
Solution Approach 2:
The coupling function is segmented into multiple independent taper elements rather than relying on a single taper. This segmentation allows each element to perform adiabatic transition efficiently while the aggregate structure provides robustness and large area.
3Reliability
If a single taper with nanometer-sized tip is used, then mode conversion is effective, but the tip is easily damaged and coupling is difficult
Solution Approach 1:
The single fragile nanometer tip is segmented into multiple nanometer tips arranged in parallel. Each tip maintains the necessary small size for effective mode conversion, while the multiplicity of tips collectively provides enhanced mechanical strength and redundancy.
Solution Approach 2:
The multi-taper structure provides inherent redundancy and robustness before damage can occur. If one taper or tip is damaged, the remaining tapers continue to function, providing a cushioning effect against complete failure.
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 multi-taper coupler enhances energetic efficiency, reduces signal loss, and is more robust to damage, offering improved coupling performance compared to conventional methods, with experimental results showing a gain of 2.41 dB using seven tapers.
Implementation Method 1
The multi-taper coupler is configured to convert adiabatically between a first propagation mode of an optical signal at the base and a second propagation mode of an optical signal at the coupling facet
Data Source
AI summary
An optical coupler includes a plurality of tapers, each of the taper-bases arranged substantially in a first plane to form a base of the optical coupler for connecting to a first optical waveguide, and the taper-tips arranged substantially non-overlapping in a second plane corresponding to a coupling facet for coupling with a second optical waveguide. This multi-taper coupler overcomes the energy loss of conventional techniques, allowing optical coupling between a variety of optical devices including optical fibers, waveguides, diodes, and switches. The multi-taper has increased information transmission efficiency, reduced loss of signal strength between coupled products, and is more robust to damage of the coupler, and the coupling area is larger than conventional couplers thereby reducing coupling complexity and increasing coupling probability.