Tunable Wavelength Filter Using Rotating Mirrors
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Solution Overview
Problem
In optical communication networks, there is a need for tunable optical filters that can dynamically modify selected or removed wavelengths, as existing filters lack the ability to reconfigure wavelength selection in modern, reconfigurable networks.
Innovation Solution
A tunable wavelength filtering device using rotating mirrors, such as MEMS tilt-mirrors, to alter the incident angle of an optical beam onto a thin film optical filter, allowing for adjustment of the filter's center wavelength by varying the angle of incidence, thereby enabling dynamic wavelength selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed optical filter is used, then the filter structure is simple, but the wavelength selection cannot be dynamically modified
Solution Approach 1:
The patent applies the dynamics principle by making the optical path configurable through movable mirrors. The first mirror can be rotated to change the angle of incidence on the fixed optical filter, and the second mirror can be rotated to redirect the filtered beam to different output ports. This dynamic adjustment capability allows wavelength tuning without changing the filter itself, resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The patent applies parameter changes by varying the angle of incidence of the optical beam on the fixed optical filter through rotation of the first mirror. By changing this angular parameter, the filter's spectral response is modified, enabling different wavelengths to be selected. This approach allows dynamic wavelength tuning while keeping the filter structure simple.
2Adaptability or versatility
If the angle of incidence is varied to tune wavelength, then wavelength selection flexibility is improved, but the alignment precision requirements increase
Solution Approach 1:
The patent applies feedback by using optical sensors to detect the position and alignment of the optical beam. These sensors provide feedback signals to control systems that adjust the mirror angles accordingly, ensuring precise wavelength selection. This feedback mechanism compensates for manufacturing tolerances and maintains high alignment precision during operation.
Solution Approach 2:
The patent applies mechanics substitution by replacing manual mechanical alignment with automated control systems. The mirrors are equipped with actuators and control circuits that automatically adjust their positions based on electrical control signals, eliminating the need for precise manual mechanical alignment and reducing the impact of manufacturing precision limitations.
3Adaptability or versatility
If multiple output ports are provided for different wavelengths, then network reconfigurability is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing a single fixed optical filter that can serve multiple wavelength selection functions. By combining this filter with rotatable mirrors that can be dynamically adjusted, the system achieves multi-wavelength capability without requiring multiple dedicated filters for each wavelength, thus reducing overall device complexity while maintaining network reconfigurability.
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 provides improved wavelength tuning range and isolation of adjacent wavelengths, enhancing the filter's performance in reconfigurable optical networks by allowing precise control over the wavelengths passed through the filter.
Implementation Method 1
A fixed optical filter is located in an optical path from the input port and to the output port and is configured to transmit light having a spectral response dependent on an angle with which a beam of light is incident thereupon
Implementation Method 2
A first mirror is located in the optical path intermediate to the input port and the optical filter, where the first mirror is configured to reflect an incident beam of light from the input port onto the fixed optical filter
Implementation Method 3
A second mirror is located in the optical path intermediate to the optical filter and the output port and is rotatable in response to a second control signal to direct a beam of light transmitted by the optical filter to the output port
Data Source
AI summary
A tunable wavelength filtering device is presented in which the tuning mechanism is based on altering the incident angle to an optical thin film coating stack, or thin film optical filter. Rotating mirrors, such as Micro-Electro-Mechanical Systems (MEMS) tilt-mirrors, are used to alter the incident angle of the optical beam coming from an input fiber, and also to aim or align the exiting beam to an output optical fiber. The optical thin film coating stack can be implemented onto a glass substrate, to form a thin film filter chip. The thin film filter chip can be fixed in place, and the incident angle and exiting angle of the optical beam is varied by adjusting the tilt angle of the two rotating mirrors.