Thin-plate LN Optical Control Device DC Drift Mitigation
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Solution Overview
Problem
Thin-plate LN optical control devices experience increased DC drift, high variation between samples, and low reproducibility due to moisture-related issues and mechanical processing challenges, particularly when thinned to tens of micrometers or less, leading to reliability and productivity concerns.
Innovation Solution
Incorporating a thin-plate LN optical waveguide element with a thinned substrate and a control electrode in an air-tight housing filled with oxygen, which suppresses DC drift and variation by maintaining a stable atmosphere, enhancing reproducibility and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the LN substrate is thinned to achieve low-drive-voltage performance and broad optical bandwidth, then the drive voltage is reduced and optical bandwidth is increased, but DC drift increases and reliability deteriorates
Solution Approach 1:
The patent fills the housing with nitrogen gas (an inert atmosphere) to exclude moisture and oxygen from the environment inside the housing. This prevents moisture-related deterioration of adhesive bonds and electrical interconnections, thereby reducing DC drift and improving reliability while maintaining the thinned substrate structure for low drive voltage and broad bandwidth
2Power
If the LN substrate is thinned to achieve low-drive-voltage performance, then the drive voltage is reduced, but the substrate becomes mechanically fragile and processing damage occurs
Solution Approach 1:
The patent bonds the thinned LN substrate to a reinforcing substrate (such as glass or ceramic) to create a composite structure. This provides mechanical reinforcement to the fragile thin substrate while maintaining the electro-optic properties needed for low drive voltage operation
3Ease of manufacture
If adhesive is used to fix the LN optical waveguide element, then the element is secured in the housing, but adhesive force deteriorates in moisture-containing atmosphere
Solution Approach 1:
The patent fills the housing with nitrogen gas to create an inert atmosphere that excludes moisture. This prevents moisture-related deterioration of the adhesive bond between the LN optical waveguide element and the housing, thereby maintaining reliable fixation
4Duration of action of moving object
If continuous voltage application is performed in moisture-containing atmosphere, then the control electrode operates continuously, but disconnection or short-circuiting occurs due to migration
Solution Approach 1:
The patent fills the housing with nitrogen gas to exclude moisture from the electrical interconnection environment. This prevents ion migration and corrosion that would cause disconnection or short-circuiting during continuous voltage application, thereby ensuring long-term reliability
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 use of oxygen in the filler gas inside the housing effectively reduces DC drift and inter-control-electrode current variation, improving the reliability and mass productivity of thin-plate LN optical control devices by stabilizing the electrical connections and reducing processing damage effects.
Implementation Method 1
there is known an optical control device that uses LN having an electro-optic effect capable of realizing high-speed response
Implementation Method 2
a Mach-Zehnder type optical waveguide formed by thermal diffusion of titanium (Ti)
Data Source
AI summary
A thin-plate LN optical control device includes: a thin-plate LN optical waveguide element which includes an optical waveguide formed by thermal diffusion of Ti in a substrate made of lithium niobate, and a control electrode that is formed on the substrate and is configured to control a light wave propagating through the optical waveguide, and in which at least a part of the substrate is thinned; and a housing that accommodates the thin-plate LN optical waveguide element in an air-tight sealing manner. Oxygen is contained in a filler gas inside the housing.