Dual-Layer Antisymmetric Bragg Gratings for Dual-Bandpass Filtering
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Solution Overview
Problem
Existing single-layer Bragg gratings face challenges in achieving dual-channel bandpass filtering in materials like silicon nitride due to a lack of suitable effective index difference between the fundamental and first order modes, making it difficult to implement dual-bandpass filters effectively.
Innovation Solution
A dual-layer Bragg grating with anti-symmetric structures having different pitches in each layer is used to reflect specific bands and allow others to pass through, utilizing materials like silicon nitride or silicon to achieve dual-bandpass filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layered Bragg grating is used in silicon nitride, then the device complexity is reduced, but the ability to achieve dual-channel bandpass filtering is lost due to lack of suitable effective index difference
Solution Approach 1:
The single-layer Bragg grating is segmented into two distinct layers, each with different pitch values. The first layer has a first pitch designed to reflect a first wavelength band, while the second layer has a second pitch designed to reflect a second wavelength band. This segmentation enables dual-channel bandpass filtering in silicon nitride platforms that previously could not achieve this functionality with a single layer.
Solution Approach 2:
The invention transitions from a single-layer two-dimensional structure to a multi-layer three-dimensional structure. By stacking multiple layers with different pitch values, the system gains an additional degree of freedom in controlling wavelength selection, enabling dual-channel filtering capability that was impossible with a single layer.
2Adaptability or versatility
If a dual-layer Bragg grating with different pitches is used, then dual-bandpass filtering capability is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention utilizes parameter changes by assigning different pitch values to different layers. The first layer has a first pitch optimized for reflecting a first wavelength band, while the second layer has a second pitch optimized for reflecting a second wavelength band. This parameter differentiation enables dual-channel filtering while the parameters are chosen to be compatible with standard fabrication tolerances.
3Reliability
If conventional Bragg gratings are used, then temperature control is required to maintain wavelength stability, but this increases power consumption
Solution Approach 1:
The invention changes the structural parameters by using multiple layers with different pitch values, which fundamentally alters the wavelength selection mechanism. This multi-layer configuration with differentiated pitches creates inherently flatter passbands that are less sensitive to temperature variations, reducing or eliminating the need for active temperature control and thereby lowering power consumption.
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 dual-layer Bragg grating efficiently reflects non-contiguous bands while minimizing fabrication complexity and enabling flat-top passbands, reducing the need for temperature control and lowering system power consumption.
Implementation Method 1
dual-layer Bragg grating with anti-symmetric structures having different pitches in each layer is used to reflect specific bands
Implementation Method 2
The dual-layer Bragg grating efficiently reflects non-contiguous bands while minimizing fabrication complexity
Data Source
AI summary
Embodiments herein describe a dual-layer Bragg grating that can be used as a dual-bandpass filter. In one embodiment, the dual-layer Bragg grating comprises at least two layers, each having an anti-symmetrical structure. In addition, the anti-symmetrical structures can have different pitches which are tuned to different bands. That is, the pitch of the anti-symmetrical structure in one layer can be set to reflect a first band in a received optical signal while the pitch of the anti-symmetrical structure in the other layer is set to reflect a second band in the received optical signal.