Tilting Mirror MEMS VOA Wavelength-Dependent Loss Reduction
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Solution Overview
Problem
Conventional tilting mirror MEMS variable optical attenuators exhibit increasing wavelength-dependent loss (WDL) as the level of attenuation increases, making it challenging to maintain equal attenuation across various wavelengths in fiber optic systems.
Innovation Solution
Designing a tilting mirror MEMS VOA with a wavelength-dependent offset in the return beam path, achieved by using a lens with high material dispersion and a wedge angle, which compensates for fiber optic mode dispersion to minimize WDL across a range of attenuation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a tilting mirror MEMS VOA is used to achieve variable optical attenuation, then the attenuation level can be adjusted, but the wavelength-dependent loss increases as attenuation increases
Solution Approach 1:
The patent changes the physical parameters of the optical system by introducing a lens with specific dispersion properties and positioning it at a precise distance from the tilting mirror. This modifies the optical path in a wavelength-dependent manner that compensates for the mirror's wavelength-sensitive attenuation characteristics, thereby reducing WDL across the operating wavelength range while maintaining adjustable attenuation levels.
Solution Approach 2:
The patent introduces a lens as an intermediary optical element between the input fiber and the tilting mirror. This lens mediates the optical interaction by creating a wavelength-dependent offset in the return beam path, which compensates for the wavelength-dependent loss introduced by the tilting mirror mechanism, thus resolving the contradiction between adjustable attenuation and WDL.
2Adaptability or versatility
If the attenuation level is increased to achieve greater power management control, then more wavelengths can be managed, but the difference in attenuation at different wavelengths becomes greater
Solution Approach 1:
The patent modifies the optical path parameters by incorporating a lens with specific dispersion characteristics positioned at a predetermined distance from the tilting mirror. This parameter change creates a wavelength-dependent offset that counteracts the increasing WDL, maintaining uniform attenuation across wavelengths even at higher attenuation levels, thus improving attenuation uniformity while preserving power management versatility.
3Device complexity
If a conventional tilting mirror MEMS VOA design is used, then the device structure is simple, but the wavelength-dependent loss cannot be minimized across wide attenuation ranges
Solution Approach 1:
The patent introduces a lens as an intermediary element that adds minimal structural complexity while effectively reducing WDL. The lens is positioned at a specific distance from the tilting mirror and requires simple alignment, making it an easy-to-implement addition that significantly improves wavelength-dependent loss performance without substantially increasing 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
The solution significantly reduces WDL, allowing for more consistent attenuation across different wavelengths, even at higher attenuation levels, thereby improving the performance of fiber optic systems.
Implementation Method 1
using a lens with high material dispersion and a wedge angle, which compensates for fiber optic mode dispersion to minimize WDL
Data Source
AI summary
A tilting mirror MEMS variable optical attenuator attenuates light over a band of wavelengths with minimum wavelength dependent loss. The attenuator includes a lens that has a wedged input face and is made from a material that has high dispersion. The lens design causes different wavelengths to travel different paths through the attenuator such that wavelength dependent loss is reduced. The attenuator may be designed to have minimum wavelength dependent loss at a specified attenuation greater than zero.