Wavelength Selective Switch Mirror Curvature Compensation
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Solution Overview
Problem
LC-based wavelength selective switches experience temperature-induced deformation of liquid crystal cells, leading to instability in insertion loss and inter-port spacing due to varying focal lengths, and face challenges in compact packaging and enhanced dispersion capability.
Innovation Solution
Incorporation of a temperature compensation module with strip elements of higher thermal expansion materials attached to a mirror to adjust the curvature of the mirror, compensating for temperature-induced deformations of LC cells, and optimizing the arrangement and materials of the beam expanding and dispersion devices for improved stability and dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid crystal cells are used for switching and attenuation, then the switch achieves good stability, mature process, and low cost, but the liquid crystal cells deform due to temperature changes causing focal length variation and deterioration of temperature stability
Solution Approach 1:
The patent applies thermal expansion by attaching a temperature compensation module consisting of strip elements made from materials with higher thermal expansion coefficients to the mirror. As temperature changes, these strips expand or contract, causing the mirror to bend and adjust its curvature. This curvature change compensates for the focal length variations caused by liquid crystal cell deformation, thereby maintaining temperature stability of the optical system.
Solution Approach 2:
The patent changes physical parameters by using materials with different thermal expansion coefficients for the compensation strips. By selecting appropriate materials and dimensions, the system adjusts the mirror's curvature parameter in response to temperature changes, counteracting the focal length drift caused by liquid crystal cell thermal deformation.
2Adaptability or versatility
If the optical path includes I/O collimator, beam expanding device, light splitting device, focusing device, and attenuation switching device, then the wavelength selective switch achieves wavelength selection capability, but the optical path becomes too large and packaging becomes difficult
Solution Approach 1:
The patent merges multiple optical functions into integrated components. The mirror serves both as a reflection element and as part of the temperature compensation system. The liquid crystal cells perform both switching and attenuation functions. The beam expanding device and light splitting device are arranged in a compact configuration where their functions overlap spatially, reducing the overall optical path length while maintaining wavelength selection capability.
3Adaptability or versatility
If the grating dispersion capability is enhanced to improve bandwidth, then the wavelength selection range increases, but the width difference of components for respective wavelengths increases making manufacturing more difficult
Solution Approach 1:
The patent applies local quality by using a blazed grating structure where the groove depth and orientation are optimized for specific wavelength ranges. Different portions of the grating have different local characteristics to handle different wavelength bands effectively. This allows enhanced dispersion capability and bandwidth while maintaining reasonable component uniformity, as each local region is optimized for its specific function rather than requiring all components to be identical.
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 enhances temperature stability and dispersion capability, ensuring consistent performance across different wavelengths and reducing the complexity of the optical path by compensating for LC cell deformations and optimizing component sizes and materials.
Implementation Method 1
a temperature compensation module provided on a side of the mirror opposite to the LC switching module, the temperature compensation module being configured to alter curvature of the mirror as temperature changes
Implementation Method 2
its liquid crystal region becomes convex at high temperature and becomes concave at low temperature
Implementation Method 3
a mirror 106 to reflect the modulated optical signal from the signal processing element 105
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
The present disclosure relates to wavelength selective switches. In one embodiment, a wavelength selective switch may include a liquid crystal (LC) -based attenuation switching device that has an LC switching module to switch an incident beam to one of a plurality of output paths. The LC switching module may include one or more LC switching cells. The LC-based attenuation switching device further includes a mirror to reflect the beam from the LC switching module so as to output the beam through a corresponding output port, and a temperature compensation module provided on a side of the mirror opposite to the LC switching module. The temperature compensation module may be configured to alter curvature of the mirror as temperature changes so as to compensate for deformation of the LC switching cells due to the temperature change.