Optical Waveguide Grating Curved Sidewalls Back Reflection
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Solution Overview
Problem
Current optical signal transmission methods face limitations in increasing signal transmission rates due to back reflection issues in semiconductor devices, which hinder the development of high-speed, downscaled electronic devices.
Innovation Solution
An optical apparatus with a grating pattern on a substrate, featuring a guiding portion, a taper portion, and a grating pattern with alternating low and high refractive index portions, where the sidewalls of the high refractive index portions have distinct focus positions to minimize back reflection by focusing light within the guiding portion and reducing index contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional optical waveguide structure is used, then the device structure is simple, but back reflection occurs during optical signal transmission
Solution Approach 1:
The waveguide structure is segmented into multiple functional portions: a guiding portion for confining light, a taper portion for gradual mode transition, and a grating pattern for coupling. This segmentation allows each portion to optimize its function while collectively reducing back reflection
Solution Approach 2:
The sidewalls of the high refractive index portions in the grating pattern are designed with curved surfaces rather than flat surfaces. This curvature helps to gradually transition the optical mode and reduce abrupt reflections, thereby minimizing back reflection into the waveguide
2Speed
If the signal transmission rate is increased using electrical signals, then the transmission speed improves, but the signal transmission rate reaches a limit due to back reflection
Solution Approach 1:
The patent transitions from electrical signal transmission through copper wires to optical signal transmission through waveguides. This substitution enables higher signal transmission rates by utilizing optical frequencies, while the specialized waveguide structure with curved grating patterns ensures transmission stability by minimizing back reflection
3Reliability
If a grating pattern with flat sidewalls is used, then the manufacturing process is simpler, but back reflection is not minimized
Solution Approach 1:
The grating pattern features curved sidewalls with specific radii of curvature instead of flat sidewalls. This curvature design optimizes the optical field distribution and reduces back reflection, while the curvature parameters can be controlled during fabrication to balance performance and manufacturability
4Stability of the object's composition
If the refractive index contrast is increased, then the light confinement is improved, but back reflection increases
Solution Approach 1:
The waveguide structure employs different refractive index distributions in different regions: the guiding portion has high refractive index for light confinement, while the taper portion and grating pattern have gradually varying refractive indices. This local quality variation allows optimal light confinement where needed while minimizing abrupt index changes that cause back reflection
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 solution effectively reduces back reflection and enhances optical coupling efficiency, thereby improving the stability and performance of optical signal transmission in semiconductor devices, allowing for higher signal transmission rates.
Implementation Method 1
The grating pattern is configured to diffract light transmitted from the optical fiber through the taper portion to confine light within the guiding portion
Implementation Method 2
Each of the plurality of high refractive index portions includes a curved inner sidewall and a curved outer sidewall having curvatures defined by circular paths. The inner sidewall and the outer sidewall of at least one of the plurality of high refractive index portions have a first focus position.
Data Source
AI summary
An optical apparatus includes an optical waveguide located on a substrate and including a guiding portion and a taper portion, and a grating pattern located on the substrate. The grating pattern includes a plurality of low refractive index portions and a plurality of high refractive index portions, which are alternately arranged in a first direction parallel to a top surface of the substrate. Each of the plurality of high refractive index portions includes a curved inner sidewall and a curved outer sidewall having curvatures defined by circular paths. The inner sidewall and the outer sidewall of at least one of the plurality of high refractive index portions have a first focus position. The inner sidewall or the outer sidewall of at least one of the plurality of high refractive index portions or a sidewall of the taper portion has a second focus position different from the first focus position.