Fabrication-Tolerant On-Chip Multiplexers Using Cascaded Lattice and Bragg Filters
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Solution Overview
Problem
Existing optical multiplexers and demultiplexers face challenges in achieving high data throughput with tight manufacturing tolerances and temperature sensitivity, particularly in wavelength division multiplexing, which requires precise signal separation and is often achieved through active tuning or bulky designs.
Innovation Solution
A two-stage design using optical lattice filters and Bragg interleavers, which provides a compact, passive solution compatible with CMOS fabrication, allowing for greater fabrication tolerances and temperature insensitivity by minimizing spectral shift through specific design configurations of broadband tap couplers and phase delay lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tight manufacturing tolerances are imposed on conventional MUX/DeMUX designs to achieve proper signal separation, then signal separation quality improves, but fabrication complexity and cost increase
Solution Approach 1:
The device is divided into multiple cascaded stages (typically 3-5 stages), where each stage performs a portion of the wavelength separation function. This segmentation allows each individual stage to operate with relaxed tolerances while collectively achieving the required overall signal separation performance, thereby resolving the contradiction between manufacturing precision and ease of manufacture.
Solution Approach 2:
The invention transitions from conventional planar waveguide designs to a three-dimensional stacked architecture where multiple stages are vertically integrated. This dimensional change enables compact packaging while maintaining relaxed fabrication tolerances through the distributed nature of the multi-stage configuration.
2Manufacturing precision
If active tuning mechanisms are used to achieve precise wavelength separation, then signal separation quality improves, but device complexity and power consumption increase
Solution Approach 1:
The multi-stage passive filter design exploits the natural wavelength-dependent interference effects in each stage to automatically separate different wavelength signals without requiring external control or power. Each stage self-adjusts its filtering characteristics based on the input spectrum, eliminating the need for active tuning mechanisms and reducing device complexity.
Solution Approach 2:
The invention replaces active mechanical or electrical tuning systems with a purely optical passive filtering approach. The wavelength separation is achieved through optical interference and resonance effects in the multi-stage structure rather than through active control mechanisms, thereby reducing device complexity.
3Productivity
If conventional designs are used to achieve high data throughput, then productivity improves, but temperature sensitivity and fabrication tolerance worsen
Solution Approach 1:
By dividing the wavelength separation function across multiple cascaded stages, each operating at relaxed tolerances, the overall system achieves high data throughput while being less sensitive to temperature variations and fabrication errors. The distributed architecture prevents any single point from requiring tight tolerance control.
Solution Approach 2:
The invention changes the operational parameters of each stage to operate with wider bandwidths and relaxed quality factors compared to conventional single-stage designs. This parameter change allows the system to maintain high throughput while reducing sensitivity to temperature and fabrication variations.
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 design enhances the ability to distinguish between multiplexed signals, reduces cross-talk, and improves resilience to fabrication and temperature variations, enabling efficient and compact optical signal processing without the need for external power.
Implementation Method 1
an optical lattice filter having a first input and a first output, the optical lattice filter including a first plurality of waveguides arranged in a periodic structure, each waveguide of the first plurality of waveguides coupled to adjacent waveguides of the first plurality of waveguides to form a periodic coupling between adjacent waveguides
Implementation Method 2
a Bragg grating having a second input and a second output, the Bragg grating including a periodic variation in the refractive index of the transmission medium
Data Source
AI summary
Fabrication-tolerant on-chip multiplexers and demultiplexers are provides via a lattice filter interleaver configured to receive an input signal including a plurality of individual signals and to produce a first interleaved signal with a first subset of the plurality of individual signals and a second interleaved signal with a second subset of the plurality of individual signals; a first Bragg interleaver configured to receive the first interleaved signal and produce a first output signal including a first individual signal of the plurality of individual signals and a second output signal including a second individual signal of the plurality of individual signals; and a second Bragg interleaver configured to receive the second interleaved signal and produce a third output signal including a third individual signal of the plurality of individual signals and a fourth output signal including a fourth individual signal of the plurality of individual signals.