Vertical Bragg Grating Filters for Compact Broadband Reflection
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Solution Overview
Problem
Conventional Bragg gratings in silicon photonics require a larger surface area and longer length to achieve broadband reflection and high reflection intensity, limiting the compactness and efficiency of photonic integrated circuits.
Innovation Solution
The use of photonic vertical grating filters with Bragg gratings located in a dielectric layer between two waveguides, each with a different grating period, reduces the surface area and length required for effective filtering by utilizing a vertical overlap region and dielectric cladding for total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Bragg gratings are used in silicon photonics, then broadband reflection and high reflection intensity are achieved, but the surface area and length required increase
Solution Approach 1:
The patent transitions from planar Bragg gratings to vertically stacked gratings in three dimensions. Multiple gratings with different periods are arranged vertically above each other, enabling broadband reflection through vertical stacking rather than horizontal extension. This dimensional change achieves enhanced reflection intensity and broader bandwidth while reducing the lateral footprint on the chip.
Solution Approach 2:
The patent implements nested Bragg gratings where multiple gratings with different periods are positioned within the same vertical column, similar to nested dolls. Each grating targets a specific wavelength band, and their vertical arrangement creates a compact structure that provides multi-wavelength filtering functionality in a reduced surface area compared to conventional lateral arrangements.
2Adaptability or versatility
If conventional Bragg gratings are used to achieve broadband reflection, then the filtering function is effective, but the length of the grating increases
Solution Approach 1:
The patent extends the grating structure into the vertical dimension by stacking multiple gratings with different periods. This vertical arrangement enables broadband reflection capability without increasing the lateral length of individual gratings. The vertical stacking allows each grating to contribute to a specific wavelength range, collectively achieving broad bandwidth coverage in a compact lateral footprint.
3Area of stationary object
If vertical grating filters are used to reduce surface area, then component density increases, but manufacturing complexity may increase
Solution Approach 1:
The patent divides the filtering function into multiple discrete vertical grating segments, each with a specific period targeting a particular wavelength range. This segmentation allows independent optimization of each grating's parameters and simplifies the design process by breaking down the complex broadband filtering requirement into manageable sub-functions, making the overall structure more manageable despite the vertical stacking.
Solution Approach 2:
The vertical grating structure serves multiple functions simultaneously: it provides wavelength-specific filtering through different grating periods, achieves broadband reflection through vertical stacking, and reduces surface area compared to conventional lateral arrangements. This multi-functionality in a single vertical structure simplifies the overall device architecture by integrating multiple filtering functions that would otherwise require separate components.
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 achieves reduced surface area and length, increasing component density and reflection intensity while being less sensitive to dimensional changes, and allows for scalable, CMOS-compatible manufacturing with improved performance characteristics.
Implementation Method 1
The cladding is configured to reflect light back into the waveguide
Implementation Method 2
A Bragg grating is formed in the dielectric layer above the waveguide
Data Source
AI summary
A photonic vertical grating filter is disclosed. The filter comprises a first waveguide, a second waveguide, and a plurality of Bragg gratings. The Bragg gratings are formed in a dielectric layer between the first waveguide and the second waveguide, and are located in a vertical overlap region between the first waveguide and the second waveguide. Each Bragg grating has a different grating period. The vertical filter uses less surface area and provides improved filtering capabilities.