Grating Coupler Middle-Raised Shape for Optical Efficiency
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Solution Overview
Problem
Optical gratings exhibit poor coupling efficiency when redirecting light between optical fibers and detectors, leading to a significant portion of redirected light not reaching the detector, necessitating an improvement in the coupling process.
Innovation Solution
A grating coupler with a middle-raised shape and varying duty cycles is designed, along with adjustable height and angle of the fiber array, to enhance coupling efficiency by reducing fiber light loss and back reflection, and optimizing the input angle of optical signals through etched metal layers forming an optical channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional optical gratings are used to redirect light between optical fibers and detectors, then light coupling is enabled, but coupling efficiency is poor with a large part of redirected light not reaching the detector
Solution Approach 1:
The patent applies local quality by varying the duty cycle of different gratings in the array. Each grating has a specific duty cycle (ratio of grating width to period) that is locally optimized for its position in the array, creating a tapered intensity profile that improves coupling efficiency. This local variation in grating properties allows different regions of the optical grating to perform different functions in the light coupling process.
Solution Approach 2:
The patent introduces adjustability and optimization capability through the ability to vary duty cycles and grating parameters. The system allows for dynamic optimization of coupling efficiency by adjusting grating characteristics to match specific application requirements, making the coupling process adaptable rather than fixed.
2Reliability
If optical gratings redirect light at shallow angles by reflecting off inner surfaces, then light can be redirected to escape from the other end, but a large part of the redirected light does not reach the detector
Solution Approach 1:
By varying the duty cycle locally across different gratings in the array, the patent creates a tapered intensity profile that concentrates light in a specific angular range. This local variation ensures that light is redirected more effectively toward the detector while reducing losses from light traveling at inappropriate angles.
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 significantly improves coupling efficiency, making it suitable for silicon photonics applications, facilitating wafer-scale testing and low-cost packaging, while ensuring high efficiency and ease of implementation in high-speed optical input/output devices.
Implementation Method 1
Light coupled from one end of the optical gratings that has been traveling transversely through the optical gratings by reflecting off the inner surfaces at shallow angles may be redirected so that it strikes the inner surfaces at a sharper angle that is greater than the critical angle of incidence
Implementation Method 2
Light coupled from one end of the optical gratings that has been traveling transversely through the optical gratings by reflecting off the inner surfaces at shallow angles
Implementation Method 3
redirected so that it strikes the inner surfaces at a sharper angle that is greater than the critical angle of incidence, thus allowing the redirected light to escape from the other end of the optical gratings
Data Source
AI summary
Disclosed are grating couplers having a high coupling efficiency for optical communications. In one embodiment, an apparatus for optical coupling is disclosed. The apparatus includes: a substrate; a grating coupler comprising a plurality of coupling gratings over the substrate, wherein each of the plurality of coupling gratings extends in a first lateral direction and has a cross-section having a middle-raised shape in a second lateral direction, wherein the first and second lateral directions are parallel to a surface of the substrate and perpendicular to each other in a grating plane; and a cladding layer comprising an optical medium, wherein the cladding layer is filled in over the grating coupler.