MEMS Mirror Pixel Gap Compensation in Wavelength Selective Switches
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Solution Overview
Problem
Optical wavelength selective switches with MEMS arrays face significant insertion loss due to finite gaps between mirror pixels, leading to information loss and attenuation, especially when channel widths exceed pixel dimensions, causing cumulative loss in complex switching networks.
Innovation Solution
Incorporating an additional optical element, such as sub-pixels in a liquid crystal array or a neutral density filter, with increased transmission characteristics at gap positions to compensate for the reduced optical throughput caused by inter-pixel gaps, or modifying MEMS mirrors with non-reflecting regions to reduce the impact of gaps on beam steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the spectral width of channels is increased to carry higher information capacity, then the information capacity increases, but the transmission loss increases due to wavelengths falling on inter-pixel gaps
Solution Approach 1:
A compensating optical element is introduced as an intermediary between the input beam and the MEMS mirror array. This element has a spectral transmission characteristic that provides increased transmission at wavelengths corresponding to inter-pixel gap positions, thereby compensating for the loss caused by gaps and enabling wider channel spectral widths without excessive transmission loss
Solution Approach 2:
The spectral transmission characteristic of the optical system is modified by introducing an element with complementary transmission properties. This changes the overall transmission parameter across the spectrum, specifically enhancing transmission at gap wavelengths while maintaining or improving capacity at channel wavelengths
2Quantity of substance
If the channel spectral width exceeds the pixel width, then more information can be transmitted, but light falls on multiple mirrors and inter-pixel gaps causing severe attenuation
Solution Approach 1:
The compensating optical element acts as a mediator that restores signal integrity for wide channels. By providing enhanced transmission at gap wavelengths, it ensures that even when light spreads across multiple pixels and gaps, the overall signal remains intact with minimal attenuation
Solution Approach 2:
The inter-pixel gaps, which normally cause harmful attenuation, are compensated by an optical element that specifically enhances transmission at those wavelengths. The harmful effect of gaps is converted into a manageable parameter through complementary transmission characteristics
3Adaptability or versatility
If multiple nodes in a switching network use the same wavelength grid, then network standardization is achieved, but cumulative insertion loss occurs due to repeated gap encounters
Solution Approach 1:
The compensating optical element is positioned at the beginning of the optical path, before light enters the MEMS array. This preliminary compensation ensures that transmission loss is mitigated at each node traversal, preventing cumulative insertion loss from building up through multiple standardized network nodes
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
Significantly reduces the transmission modulation effect caused by inter-pixel gaps, resulting in a flatter spectral response and minimized information loss across the optical beam handling system, even in complex switching networks.
Implementation Method 1
an optical element disposed in juxtaposition to the MEMS array, such that light impinging on the MEMS array also traverses the optical element, the optical element having a spatial transmission characteristic which shows increased transmission in at least some positions through which light impinging on the gaps passes
Data Source
AI summary
An optical device compensates for decreased transmission of light caused by gaps between mirrors of a MEMS array. The optical device employs MEMS mirrors having non-reflecting regions on them disposed such that reflecting regions of the MEMS mirrors have substantially the same optical throughput, or an additional optical element having increased transmission at those spatial positions where light impinging on the gaps passes through. Alternatively, the optical device may employ a filter having spectral transmission characteristic with increased transmission at those wavelengths of dispersed light that impinge on the gaps.