Optical Modulation Device with Segmented Electrodes and Light Absorption
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Solution Overview
Problem
The variation in optical characteristics of optical modulation devices using protruding optical waveguides with segmented electrodes is caused by interference of leaked light beams at gaps between electrode segments, leading to deteriorated extinction ratios.
Innovation Solution
The optical modulation device employs a multilayer substrate structure with specific refractive index relationships and a light absorbing material to suppress interference between leaked light beams, using a multilayer substrate with optical waveguide and support layers having refractive indices n0 > n1 and n2 > n1, and a light absorbing material on the substrate back surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a segmented electrode is used as a modulation electrode in a protruding optical waveguide, then impedance matching between the modulation electrode and drive circuit is achieved, but interference of leaked light beams at gaps between electrode segments causes variation in optical characteristics such as extinction ratio
Solution Approach 1:
A light-absorbing layer is introduced as an intermediary substance between the protruding optical waveguide and the substrate. This layer specifically targets and absorbs the leaked light beams that escape from the waveguide, preventing them from interfering with the optical characteristics. The light-absorbing layer acts as a mediator that resolves the harmful effect of light leakage caused by the segmented electrode structure, while maintaining the impedance matching benefits of segmentation.
2Manufacturing precision
If the protruding portion is formed with high accuracy in wafer process, then manufacturing precision is improved, but variation in optical characteristics still occurs due to light beam interference
Solution Approach 1:
Instead of trying to prevent light leakage at the source (which would require even higher manufacturing precision), the invention converts the harmful leaked light into a manageable problem by introducing a light-absorbing layer. The leaked light, which was causing interference and variation in optical characteristics, is now systematically absorbed by the dedicated light-absorbing material, transforming a harmful effect into a controlled and eliminated phenomenon.
3Reliability
If a light absorbing material is added to suppress interference, then optical characteristics are improved, but device complexity increases
Solution Approach 1:
The light-absorbing layer is not applied throughout the entire device but is specifically positioned in the region where light leakage occurs - between the protruding optical waveguide and the substrate. This localized application of the light-absorbing material addresses the specific problem of light beam interference without unnecessarily complicating other parts of the device structure, thereby minimizing the increase in overall device complexity.
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 reduces the intensity of leaked light beams, minimizing their interference and improving optical characteristics such as extinction ratio.
Implementation Method 1
a light absorbing material that absorbs light in a wavelength range of the light wave propagating through the optical waveguide
Implementation Method 2
a refractive index n0 of the optical waveguide layer, a refractive index n1 of the first support layer, and a refractive index n2 of the second support layer have a relationship of n0 > n1 and n2 > n1
Data Source
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AI summary
An optical modulation device includes a substrate including a multilayer portion, an optical waveguide layer on which an optical waveguide is formed in the multilayer portion, and a modulation electrode formed to be divided into a plurality of segments along a propagation direction of the optical waveguide to control a light wave propagating through the optical waveguide, in which in all sections of the electrode or a section excluding a part of the sections, a clearance, measured in an extending direction of the optical waveguide, between gaps between adjacent segments is constant, the multilayer portion includes the optical waveguide layer, a first support layer, and a second support layer, and a refractive index n0 of the optical waveguide layer, a refractive index n1 of the first support layer, and a refractive index n2 of the second support layer have a relationship of n0 > n1 and n2 > n1.