Wavelength Selective Optical Switch Using Micromirror Arrays
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Solution Overview
Problem
Conventional optical switches in telecommunications networks face challenges in efficiently switching multiple signals carried on different wavelengths within multiple optical fibers due to issues with mirror array yield, optical path length, and the need for wavelength-independent input and output ports in mesh networks.
Innovation Solution
A wavelength-selective optical switch using two-dimensional arrays of micromirrors and interference filters to separate and recombine optical wavelengths, with mechanisms for non-blocking functionality and redundant capacity to handle finite mirror array yields, allowing for arbitrary wavelength switching and addition/dropping in mesh networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavelength-dispersive media such as gratings are used to separate optical beams, then optical beams at separate wavelengths can be provided, but long optical path lengths are required to provide sufficient beam separation for closely spaced wavelengths
Solution Approach 1:
The optical spectrum is segmented into multiple wavelength bands, with each band being processed separately through dedicated optical paths. This allows for sufficient spatial separation of closely spaced wavelengths without requiring excessively long overall optical paths, as each band is handled independently through the micromirror array switching fabric.
Solution Approach 2:
The patent transitions from one-dimensional wavelength separation (using gratings along a single optical path) to two-dimensional wavelength routing by spatially distributing multiple wavelength bands across different input and output fibers. The micromirror array provides additional spatial dimensions for beam separation and routing, eliminating the need for long optical paths while maintaining precise wavelength separation.
2Productivity
If mirror arrays are fabricated, then optical switching can be implemented, but perfect yield is difficult to achieve leading to blocking network operation due to defective mirrors
Solution Approach 1:
Different regions of the micromirror array are assigned different functions: some mirrors handle critical wavelength routing while others provide redundant capacity. The system incorporates dedicated add/drop ports with alternative routing paths that bypass defective mirrors, ensuring that local defects do not block entire network operations. This local differentiation of quality and function maintains overall system reliability despite manufacturing imperfections.
Solution Approach 2:
The optical switch is designed with redundant optical paths and spare capacity built in before deployment. Alternative routing paths are pre-configured through the wavelength selective switches and add/drop ports, so that if mirrors fail during operation, traffic can be rerouted without blocking network operation. This prior cushioning against potential mirror failures ensures continuous network operation.
3Adaptability or versatility
If conventional optical switches are used, then basic wavelength switching can be performed, but wavelength independent input and output ports are not provided limiting add and drop capability
Solution Approach 1:
The optical switch incorporates universal add and drop ports that can handle any wavelength independently of the main switching fabric. These wavelength-independent ports provide universal functionality for adding and dropping arbitrary wavelengths at mesh network nodes, while the core micromirror array handles the majority of wavelength routing. This multi-functional design achieves high adaptability without proportionally increasing overall device complexity.
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
Enables efficient switching of multiple wavelengths between optical fibers with improved reliability and flexibility, reducing the impact of mirror yield defects and optimizing optical path lengths for robust network operation.
Implementation Method 1
Each input fiber is connected to a number of interference filters that separate the wavelengths from the input fiber into a number of wavelength bands
Implementation Method 2
A free-space optical switch including a two-dimensional array of mirrors receives the wavelength separated beams, separates the wavelength bands from one another, and switches selected wavelength bands and selected individual wavelengths from any input fiber to any output fiber
Data Source
AI summary
A wavelength-selective optical switch for switching arbitrary wavelengths between optical fibers in mesh networks, using interference filters for separating optical wavelengths, and two-dimensional arrays of micromirrors for switching. Broadband switch inputs and outputs are provided for adding and dropping arbitrary wavelengths at each node of the network. A two-stage multiplexer and two-stage demultiplexer are provided to simplify the free-space demultiplexer and multiplexer. Mechanisms are provided that allows full non-blocking functionality in the presence of finite yield of the micromirror arrays.