Optical Modulator Electrode Thickness Control
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Solution Overview
Problem
Existing modulators exhibit performance dispersion due to manufacturing inaccuracies, leading to inconsistent modulation efficiency and bandwidth, primarily caused by variations in the thickness of the dielectric layer and electrode positions.
Innovation Solution
A modulator manufacturing process that involves precise control of the dielectric layer thickness and electrode positioning, using a buried thermal silicon dioxide layer with a thickness of 20 nm +/- 1 nm, and a thinned intermediate part to confine the optical signal and reduce capacitive errors, ensuring consistent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a thin dielectric layer is used to achieve good modulation efficiency and low propagation losses, then modulation efficiency is improved, but manufacturing precision deteriorates due to difficulty in controlling thickness within tight tolerances
Solution Approach 1:
The patent applies preliminary action by forming the dielectric layer with a predetermined thickness (e2ini) using a controlled growth process before electrode fabrication. This preliminary formation with built-in thickness control mechanisms ensures that the critical dimension is established early in the manufacturing process with minimal subsequent variation, resolving the contradiction between achieving thin layer benefits and maintaining manufacturing precision.
2Ease of manufacture
If standard manufacturing processes are used, then ease of manufacture is maintained, but performance consistency deteriorates due to capacitive dispersion from thickness variations
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dielectric layer thickness parameter (maintaining it within e2ini ± 5 nm) and using a specific thickness range (10-25 nm) that optimizes both modulation efficiency and performance consistency. This parameter control is achieved through controlled growth processes that inherently limit thickness variation, thereby improving reliability without significantly complicating the manufacturing process.
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 process achieves homogeneous performance across modulators by minimizing capacitive dispersion and maintaining high modulation efficiency, reducing the impact of manufacturing inaccuracies on bandwidth and modulation speed.
Implementation Method 1
the charge carrier density at the interfaces between the dielectric layer and the proximal ends of the first and second electrodes is modified
Implementation Method 2
By applying a potential difference between the first and second electrodes, the charge carrier density at the interfaces between the dielectric layer and the proximal ends of the first and second electrodes is modified. This induces a change in the propagation losses and the propagation index seen by the guided optical field
Data Source
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AI summary
This modulator (580) comprises: - a first electrode (120) extending, along a transverse direction, from a proximal end to a distal end via an intermediate portion, - a second electrode (582) extending from a proximal end (32) to a distal end (31) via an intermediate portion (584), - a dielectric layer (20) interposed between the proximal ends of the first and second electrodes. The proximal end (32) of an electrode, selected from the group consisting of the first and second electrodes (120; 582), is thicker than the intermediate portion (584) of that electrode, the thickness of the intermediate portion of the selected electrode being for this purpose less than 0.8e, where e is the maximum thickness of the proximal end of the selected electrode.