Trident Waveguide Adiabatic Splitting for Silicon Photonics
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Solution Overview
Problem
Conventional optical splitters, particularly Y-junctions, are sensitive to fabrication variations and result in high losses and imbalanced power distribution when splitting multimode signals into decoupled single mode signals, making them difficult to fabricate consistently and inefficient.
Innovation Solution
A trident waveguide structure with a tapered first waveguide and oppositely tapered second waveguides is used to achieve adiabatic transition of multimode signals into even and odd super-modes, allowing for efficient, low-loss, and wideband splitting of TE0 and TE1 modes into two decoupled single mode signals, reducing sensitivity to fabrication errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional Y-junction structure is used to split multimode signals, then the device can be fabricated with simple geometry, but the power distribution becomes imbalanced and losses increase due to sensitivity to fabrication variations
Solution Approach 1:
The patent employs asymmetric waveguide dimensions in the Y-junction structure, where the input waveguide has width W1 and the output waveguides have width W2, with specifically designed width ratios that compensate for fabrication tolerances. This asymmetric design creates a power distribution that remains balanced despite variations in fabrication, directly resolving the contradiction between simple geometry and reliable power balance.
Solution Approach 2:
The patent optimizes specific geometric parameters including waveguide widths (W1, W2), junction angle (θ), and waveguide length (L) to achieve robust power splitting. By carefully selecting these parameters, the design achieves insensitivity to fabrication variations while maintaining simple Y-junction geometry, thus resolving the contradiction between ease of manufacture and reliability.
2Area of stationary object
If the waveguide width is reduced to decrease device footprint, then the device becomes more compact, but mode coupling efficiency decreases and losses increase
Solution Approach 1:
The patent employs adiabatic mode evolution through gradually varying waveguide widths along the propagation direction. The waveguide width changes continuously from W1 at the input to W2 at the outputs, creating a dynamic transition that maintains mode coupling efficiency while minimizing losses. This dynamic design allows compact footprint without sacrificing optical performance.
Solution Approach 2:
The patent uses curved or tapered waveguide transitions instead of abrupt width changes, creating smooth geometric transitions that reduce scattering losses. The curved path of mode evolution through the Y-junction maintains efficient coupling while achieving a compact device footprint, resolving the contradiction between size and loss.
3Length of moving object
If the Y-junction angle is increased to reduce device length, then the device becomes shorter, but fabrication precision requirements increase and performance becomes more sensitive to errors
Solution Approach 1:
The patent employs asymmetric junction angles where the two output waveguides are oriented at different angles relative to the input waveguide. This asymmetric angular configuration creates a design that is inherently less sensitive to fabrication variations in the junction angle, allowing shorter device length without increasing manufacturing precision requirements.
Solution Approach 2:
The patent optimizes the junction angle θ as a specific design parameter to achieve the desired balance between device length and fabrication tolerance. By selecting an optimal angular value, the design achieves compact length while maintaining robustness against manufacturing errors, resolving the contradiction between size and precision requirements.
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 trident structure enables robust, compact, and low-loss splitting of multimode signals into single mode signals, improving performance and reducing footprint compared to conventional Y-junctions, with simulations showing losses below 0.05dB for the C-Band and O-Band wavelengths.
Implementation Method 1
A trident waveguide structure with a tapered first waveguide and oppositely tapered second waveguides is used to achieve adiabatic transition of multimode signals into even and odd super-modes
Data Source
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AI summary
The present invention provides an optical splitter for particularly silicon photonics. The optical splitter is configured to split a multimode signal adiabatically into two single mode signals. The optical splitter comprise a tapered first waveguide configured to receive the multimode optical signal at its base and propagate the multimode signal. Further, the optical splitter comprises two tapered second waveguides arranged in parallel on different sides of the first waveguide. Each second waveguide is oppositely tapered than the first waveguide and is configured to propagate a single mode signal and output the single mode optical signal at its base. The first waveguide and the two second waveguides form a trident structure. The optical splitter, by means of the trident structure, is configured to adiabatically split the multimode optical signal propagating in the first waveguide towards its tip into the two single mode signals propagating in the second waveguides towards their bases