Silicon Nitride Phase Modulator with Transparent Heating Element
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Solution Overview
Problem
Existing phase modulators with metallic heating elements face inefficiencies in modulation due to the need for the heating element to be positioned at a distance from the waveguide, leading to increased length and reduced compactness, while also potentially disrupting the optical signal.
Innovation Solution
A phase modulator design featuring a waveguide made of silicon nitride with a heating element composed of indium tin oxide or amorphous carbon, where the heating element is in direct contact with or closely proximate to the waveguide, allowing for efficient modulation without disrupting the optical signal, and is embedded within a thermally and electrically insulating material to manage temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metallic heating element is used to modify the waveguide temperature, then the phase modulation function is achieved, but the heating element must be positioned at a distance from the waveguide which increases the modulator length and reduces compactness
Solution Approach 1:
The patent introduces an intermediate dielectric layer between the metallic heating element and the silicon nitride waveguide. This intermediary layer enables thermal coupling for phase modulation while electrically isolating the metal from the waveguide, allowing the heating element to be positioned much closer to the waveguide without direct contact, thus reducing modulator length while maintaining functionality
Solution Approach 2:
The patent employs a composite structure combining metallic heating element, dielectric intermediate layer, and silicon nitride waveguide. This composite material approach enables simultaneous achievement of thermal conduction (for heating), electrical insulation (to prevent signal disruption), and optical transparency (to maintain waveguide performance), resolving the contradiction between compactness and functional effectiveness
2Length of stationary object
If a metallic heating element is positioned close to the waveguide to reduce length, then compactness is improved, but the metal may disrupt the optical signal
Solution Approach 1:
The dielectric intermediate layer serves as a mediator that optically isolates the metallic heating element from the silicon nitride waveguide. This intermediary prevents the metal from disrupting the optical signal while still allowing thermal energy to reach the waveguide for phase modulation, enabling close positioning without signal disruption
Solution Approach 2:
The patent applies local quality by using a dielectric material with specific properties (electrically insulating but thermally conductive and optically transparent) at the critical interface between metal and waveguide. This localized material selection ensures that only the necessary thermal interaction occurs while preventing harmful optical and electrical interactions
3Use of energy by moving object
If the heating element is in direct contact with the waveguide to maximize heating efficiency, then modulation efficiency is improved, but the metal contact may cause electrical issues and disrupt the optical signal
Solution Approach 1:
The dielectric intermediate layer acts as an intermediary that enables efficient thermal transfer from the metallic heating element to the silicon nitride waveguide while simultaneously providing electrical insulation and optical isolation. This intermediary maintains heating efficiency by minimizing thermal resistance while preventing the harmful effects of direct metal-waveguide contact
Solution Approach 2:
The patent optimizes the thickness and material properties of the dielectric intermediate layer to achieve the right balance between thermal conduction (for heating efficiency) and electrical/optical isolation (to prevent disruption). By carefully controlling the intermediate layer parameters, the system achieves high heating efficiency without the negative effects of direct metal contact
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
This design enhances modulation efficiency, reduces the length of the modulator, and maintains signal integrity by using a transparent heating element that is either in contact with or closely spaced to the waveguide, offering improved compactness and performance compared to traditional metallic heating element configurations.
Implementation Method 1
When a control current circulates in the portion of the metallic layer making up the heating element, this results in a corresponding increase in its temperature by the Joule effect, and therefore of the waveguide positioned near the heating element
Data Source
AI summary
The present disclosure relates to a method including the following steps: a) forming a waveguide from a first material, the waveguide being configured to guide an optical signal; b) forming a layer made of a second material that is electrically conductive and transparent to a wavelength of the optical signal, steps a) and b) being implemented such that the layer made of the second material is in contact with at least one of the faces of the waveguide, or is separated from the at least one of the faces by a distance of less than half, preferably less than a quarter, of the wavelength of the optical signal. The application further relates to a phase modulator, in particular obtained by such a method.