Plasmonic Micro-Ring Modulator for Compact Low-Loss Optical Modulation
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Solution Overview
Problem
Existing silicon micro-ring modulators are limited by the weak plasma dispersion effect of silicon, making it difficult to achieve larger modulation depths at a smaller size, and they suffer from high on-chip loss due to free carrier absorption.
Innovation Solution
A micro-ring modulator is designed with a straight waveguide coupled to a surface plasmon polariton micro-ring resonator, utilizing a silicon-on-insulator structure and epsilon-near-zero materials to reduce size and loss, enabling modulation with high efficiency and low transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based micro-ring modulator is used, then compatibility with CMOS processes and fabrication of high refractive index waveguides is achieved, but modulation depth is limited due to weak plasma dispersion effect
Solution Approach 1:
The patent employs a composite structure combining silicon waveguides with metal (gold or silver) micro-ring resonators. The silicon provides CMOS compatibility and waveguide functionality, while the metal resonators provide strong plasma dispersion effect for modulation. This composite approach allows each material to contribute its advantageous properties to the overall device performance.
Solution Approach 2:
The patent introduces a dielectric layer as an intermediary between the silicon waveguide and the metal micro-ring resonator. This dielectric layer serves as a coupling medium that enables efficient energy transfer from the waveguide to the resonator while maintaining the beneficial interactions between the silicon and metal components.
2Volume of moving object
If existing silicon micro-ring modulator size is reduced, then device compactness is improved, but modulation performance deteriorates due to weak plasma dispersion effect
Solution Approach 1:
The patent replaces the traditional silicon-based plasma dispersion mechanism with a metal-based surface plasmon polariton mechanism. The metal micro-ring resonators generate surface plasmons that exhibit stronger plasma dispersion effects, enabling effective modulation in a compact size that would not be achievable with pure silicon structures.
Solution Approach 2:
The patent changes the material parameter from silicon to metal (gold or silver) for the micro-ring resonator, which fundamentally alters the plasma dispersion characteristics. This material parameter change enables strong modulation effects in a reduced size by leveraging the enhanced plasma dispersion properties of metals compared to silicon.
3Ease of manufacture
If silicon-based modulator is used, then fabrication is simplified, but optical loss increases due to free carrier absorption
Solution Approach 1:
The patent segments the modulator into distinct functional components: silicon waveguides for light transmission and metal micro-ring resonators for modulation. By separating these functions into different materials, the design allows the silicon to handle transmission with low loss while the metal handles modulation, reducing overall optical loss compared to using silicon for both functions.
Solution Approach 2:
The dielectric layer acts as an intermediary that couples the silicon waveguide to the metal resonator, enabling efficient energy transfer while protecting the metal from direct contact with the silicon. This intermediary structure reduces optical loss by minimizing direct interaction between the silicon and metal components.
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 modulator achieves a small size of about 1 μm, low optical signal loss, and high modulation bandwidth, addressing the limitations of existing silicon-based modulators.
Implementation Method 1
the surface plasmon polariton micro-ring resonator configured for modulating an intensity of an optical signal with a wavelength corresponding to the surface plasmon polariton micro-ring resonator
Data Source
AI summary
Disclosed are a micro-ring modulator and a method for manufacturing a micro-ring modulator. The micro-ring modulator includes at least one straight waveguide and at least one surface plasmon polariton micro-ring resonator coupled to the straight waveguide. The straight waveguide is configured for transmitting an optical signal; and the surface plasmon polariton micro-ring resonator is configured for modulating an intensity of an optical signal with a wavelength corresponding to the surface plasmon polariton micro-ring resonator.