Patterned Optical Modulator Waveguide for DC Drift Suppression
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Solution Overview
Problem
Existing optical modulators suffer from significant direct current drift, leading to a short lifespan due to the large change in light output operating points over time, which existing waveguide shapes are insufficient in addressing effectively.
Innovation Solution
The optical modulator features a patterned RF and DC portion waveguide design with the DC portion having a larger sectional area and specific protrusion configurations to reduce direct current drift, including protrusions that deviate from the center and increased impedance to minimize impedance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC bias is applied to the optical waveguide, then the optical modulator can maintain a stable operating point, but the direct current drift becomes large causing short lifespan
Solution Approach 1:
The waveguide is divided into two distinct sections: a DC portion waveguide for applying direct current bias and an RF portion waveguide for applying modulated signals. This segmentation allows each section to be optimized for its specific function, with the DC portion having a larger sectional area to reduce current density and minimize drift effects on the overall device lifespan.
Solution Approach 2:
Different sections of the waveguide are given different properties: the DC portion waveguide has a larger sectional area to reduce current density and minimize drift, while the RF portion waveguide has a smaller sectional area optimized for signal modulation. This local differentiation allows the system to simultaneously achieve stable operating points and extended lifespan.
2Reliability
If the waveguide sectional area is increased to reduce current density, then the direct current drift is suppressed, but the device complexity increases
Solution Approach 1:
The waveguide is divided into two distinct sections: a DC portion waveguide for applying direct current bias and an RF portion waveguide for applying modulated signals. This segmentation allows each section to be optimized for its specific function, with the DC portion having a larger sectional area to reduce current density and minimize drift effects on the overall device lifespan.
Solution Approach 2:
The waveguide structure transitions from a uniform single-dimension design to a multi-dimensional structure with varying sectional areas along the waveguide length. The DC portion has a larger sectional area while the RF portion has a smaller sectional area, creating a gradient structure that optimizes both drift suppression and signal modulation performance.
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 effectively suppresses direct current drift, extending the modulator's lifespan by reducing impedance changes and maintaining stable light output over extended periods.
Implementation Method 1
a Mach-Zehnder optical modulator in which an optical waveguide is formed by means of titanium (Ti) diffusion in the vicinity of the surface of a lithium niobate single-crystal substrate
Data Source
AI summary
An optical modulator, including: a substrate; a plurality of electro-optic material layers formed on the substrate; and an electrode formed on the electro-optic material layer; wherein the electro-optic material layer has a patterned RF portion waveguide that applies a modulated signal and a patterned DC portion waveguide that applies a direct current bias signal; and on a section perpendicular to a light propagation direction, the sectional area of the DC portion waveguide is greater than the sectional area of the RF portion waveguide.