Optical Waveguide Element Undesired Light Extraction
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Solution Overview
Problem
Optical waveguide devices face challenges in efficiently guiding undesired light from integrating optical waveguide combining portions to the outside, particularly with thin substrates where re-coupling of undesired light with signal light is prevalent, leading to degradation in optical characteristics such as extinction ratio and signal crosstalk.
Innovation Solution
The optical waveguide device employs an undesired-light waveguide separated by a main waveguide at intersections, with specific intersection angles and distances, and varying widths to prevent re-coupling and efficiently guide undesired light outside, even in thin substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If optical waveguides are integrated with multiple combining portions, then device functionality is improved, but undesired light from internal combining portions cannot be efficiently removed
Solution Approach 1:
The substrate is divided into a light-guiding region containing the main waveguide and a light-receiving region separated by a boundary. Undesired-light waveguides extend into the light-receiving region to extract undesired light away from the main waveguide, preventing re-coupling while maintaining integration benefits.
Solution Approach 2:
Undesired light is extracted from the integrating optical waveguide combining portions through dedicated undesired-light waveguides that guide this light to the light-receiving region, separating it from the signal light path in the main waveguide.
2Speed
If thin plate substrates are used, then frequency bandwidth and driving voltage are improved, but re-coupling of undesired light with signal light increases
Solution Approach 1:
The problem is solved by transitioning from a two-dimensional planar waveguide structure to a three-dimensional structure that extends vertically into the substrate. Undesired-light waveguides penetrate through the boundary into the light-receiving region, utilizing the depth dimension to extract undesired light before it can re-couple with signal light in the thin substrate.
3Object-generated harmful factors
If shielding means or external waveguides are provided, then radiation-mode light removal is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The undesired-light waveguides are merged with the main waveguide structure, sharing the same substrate and being formed through integrated manufacturing processes. This combining approach removes undesired light effectively while avoiding the need for separate shielding components or externally attached waveguides.
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 configuration effectively suppresses re-coupling of undesired light with signal light, maintaining optical characteristics and facilitating efficient removal of undesired light from the substrate, especially in thin plate substrates where re-coupling is a significant issue.
Implementation Method 1
an optical waveguide is formed on a dielectric substrate of lithium niobate or the like... an optical waveguide that guide the higher-mode light to the outside is provided
Implementation Method 2
the undesired-light waveguide is separated by the main waveguide interposed therebetween at the intersection in which the undesired-light waveguide and the main waveguide intersect each other, it is possible to prevent the undesired-light waveguide from coming in contact with the main waveguide to re-couple undesired light with signal light
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
An optical waveguide device is provided which can efficiently guide undesired light to the outside of a substrate or the outside of the overall optical waveguides even when optical waveguides are integrated. In the optical waveguide device, an optical waveguide is formed on a substrate, the optical waveguide includes a main waveguide in which signal light propagates and an undesired-light waveguide for removing undesired light from the main waveguide, and the undesired-light waveguide is separated by the main waveguide interposed therebetween at an intersection in which the undesired-light waveguide and the main waveguide intersect each other.