Taper Waveguide Section for Single-Mode Operation in Thin Substrates
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Solution Overview
Problem
The reduction in size of optical circuits results in a decrease in cross-sectional area of optical waveguides, leading to multi-mode propagation, increased coupling loss, and degraded signal reproducibility, particularly when the substrate thickness is 10 μm or less, making it difficult to maintain single-mode operation with high precision.
Innovation Solution
The implementation of a taper waveguide section with a trench width of 10 μm or less on both sides of the ridge waveguide, which continuously changes the width or depth to transition between single-mode and multi-mode propagation, and the use of focused ion beam or laser beam processes for precise manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the substrate thickness is reduced to 10 μm or less to lower drive voltage and improve high frequency response, then the drive voltage and high frequency response characteristics are improved, but the optical waveguide cross-sectional area decreases causing multi-mode propagation and increased coupling loss
Solution Approach 1:
The patent applies local quality by creating a taper waveguide section where the waveguide width varies along its length. The waveguide has a wider section (first width) in the single-mode region and a narrower section (second width) in the multi-mode region, allowing different sections to have different functional properties. This enables the waveguide to maintain single-mode propagation in critical coupling regions while allowing multi-mode operation in other regions, thus resolving the contradiction between thin substrate requirements and signal quality.
2Volume of moving object
If the optical circuit size is decreased to improve integration, then the device size is reduced, but the optical waveguide cross-sectional area decreases leading to multi-mode waveguide configuration
Solution Approach 1:
The patent employs dynamics by creating a waveguide with varying cross-sectional dimensions along its length. The waveguide transitions from a wider configuration supporting single-mode propagation to a narrower configuration supporting multi-mode propagation. This dynamic variation in waveguide geometry allows the system to maintain single-mode operation in regions requiring high precision while enabling compact integration in other regions.
3Reliability
If the trench width is reduced to 1 μm or less to maintain single-mode propagation in thin substrates, then single-mode operation is achieved, but the manufacturing precision requirement becomes extremely high
Solution Approach 1:
The patent applies parameter changes by varying the waveguide dimensions (width and/or depth) along its length to create distinct single-mode and multi-mode sections. Instead of maintaining a uniform narrow trench width of 1 μm or less throughout the entire waveguide, the design allows the waveguide to have different dimensions in different regions. This enables single-mode propagation where required while relaxing manufacturing precision requirements in other regions.
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 approach allows for stable single-mode operation, reducing signal-to-noise ratio and optical insertion loss degradation, while enabling precise manufacturing of optical control devices with thin substrates, and enhancing coupling efficiency and conversion efficiency in nonlinear optical devices.
Implementation Method 1
the use of focused ion beam or laser beam processes for precise manufacturing
Implementation Method 2
the use of focused ion beam or laser beam processes for precise manufacturing
Data Source
AI summary
The purpose of present inventions is to provide an optical control device having a single-mode waveguide in the optical control device having the ridge waveguide, and to stably manufacture and provide the optical control device having the single-mode waveguide with high precision even when the substrate is a thin plate with the thickness of 10 μm or less. An optical control device having a substrate 1 formed with an optical waveguide, in which the substrate is a thin plate with a thickness of 10 μm or less, at least a portion of the optical waveguide is configured as a ridge waveguide 21, a trench 20 having a width of 10 μm or less is formed on both sides of at least portions of the ridge waveguide, and a taper waveguide section (area B) continuously changes a light propagation mode of the waveguide between a single-mode and a multi-mode by continuously changing the width or depth of the trench. Additionally, it is desirable that the taper waveguide section is disposed at least in one of a light input section and a light output section, and light propagating through the waveguide is in the single-mode in a section in which the taper waveguide section is disposed.