Multi-Input Multi-Output Optical Switch Using LCOS Array
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Solution Overview
Problem
Existing wavelength selective switches in optical networks face issues such as wavelength component reversal, unequal dispersion characteristics, complex and costly mirror designs, and impractical mirror sizes, leading to transmission band degradation and port-to-port crosstalk.
Innovation Solution
A multi-input multi-output optical switch design featuring optical demultiplexing, deflection, and multiplexing elements with spatial phase modulation and liquid-crystal elements, where the beam waist is positioned midway between deflection elements, allowing for equal input angles to the diffraction grating and reducing the need for large mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a total reflection mirror is used to change the optical path in a wavelength selective switch, then the optical signal can be switched, but the mirror requires an impractically large size and complex shape, leading to poor productivity and high cost
Solution Approach 1:
The patent divides the optical switching function into multiple smaller mirror elements arranged in an array, where each element handles a specific angular range or wavelength component. This segmentation allows each mirror element to be small and simple to fabricate, while collectively they achieve the required optical path switching functionality.
Solution Approach 2:
The patent transitions from using a single large mirror in three-dimensional space to using a two-dimensional array of small mirror elements. This dimensional change allows the system to achieve the same optical path control with much smaller individual components that are easier to manufacture and assemble.
2Loss of energy
If the beam waist is positioned on the MEMS mirror arrays, then reflection efficiency is increased, but the mirror size becomes impractically large
Solution Approach 1:
The patent segments the beam waist position across multiple small mirror elements in an array, where each element captures a portion of the beam. This allows the system to maintain high reflection efficiency for the entire beam while using only small mirror areas for each individual element.
Solution Approach 2:
The array of small mirror elements collectively performs the function that would require a single large mirror, with each element being multi-functional in handling different angular or wavelength components of the optical signal.
3Adaptability or versatility
If different input angles are used for signals from different ports, then port-specific routing is achieved, but the diffraction grating exhibits unequal dispersion characteristics, degrading transmission band
Solution Approach 1:
The patent applies different local properties to different regions of the mirror array, where each mirror element or group of elements is optimized for handling signals from specific input ports. This allows each local region to perform port-specific routing while maintaining uniform dispersion characteristics through localized optimization.
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 enables switching of all WDM wavelengths with equivalent spectral properties, eliminates the need for impractically large mirrors, and improves crosstalk performance by using a waveguide-type front-end optical system with LCOS, enhancing design flexibility and reducing zero-order light effects.
Implementation Method 1
an optical demultiplexing element that demultiplexes an optical signal from the at least one input port into wavelength-separated optical signals
Implementation Method 2
at least one first optical deflection element that deflects the wavelength-separated optical signal incoming from the optical demultiplexing element to change a traveling direction for each wavelength
Data Source
AI summary
The discloser provides a multi-input and multi-output optical switch capable of switching over all WDM wavelengths. An optical switch according to one embodiment includes: an optical demultiplexing element (3) that demultiplexes an optical signal from at least one input port into individual wavelengths; a first optical deflection element (5), which deflects an incident optical signal, that deflects the wavelength-separated optical signal incoming from the optical demultiplexing element to change a traveling direction for each wavelength to a switch axis direction perpendicular to a wavelength dispersion axis direction; a second optical deflection element (8) that deflects the optical signal incoming from the first optical deflection element to change the traveling direction to the switch axis direction for output to at least one of the output ports; and an optical multiplexing element (10) that multiplexes the optical signal with the different wavelengths incoming from the second optical deflection element.