Liquid Crystal Diffraction Element Wavelength Selective Switch
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Solution Overview
Problem
Existing wavelength selective switches face challenges in miniaturization and high performance due to increased crosstalk from diffraction gratings and the need for additional liquid crystal elements for intensity control, which also increase device size and cost.
Innovation Solution
A wavelength selective switch configuration utilizing a liquid crystal diffraction element with a continuously rotating optical axis alignment pattern, combined with a polarization controller and a deflection element, where the dispersive element is either transmissive or reflective, and optimized with specific refractive index and film thickness relationships to minimize crosstalk and enhance miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffraction grating is used as the dispersive element, then the wavelength selective switch can demultiplex light, but crosstalk increases due to unintended higher-order light and the device size increases
Solution Approach 1:
The patent changes the fundamental parameter of the dispersive element from a conventional diffraction grating to a liquid crystal diffraction element. This parameter change enables dynamic control of diffraction patterns and eliminates higher-order light issues, thereby reducing crosstalk while allowing for compact device design through electrical tuning of the liquid crystal properties.
Solution Approach 2:
The patent employs a composite structure combining liquid crystal material with diffraction element properties. The liquid crystal diffraction element integrates the dispersive function with the liquid crystal's electro-optic properties, creating a multifunctional component that reduces overall device size while improving wavelength selectivity and reducing crosstalk.
2Reliability
If an additional liquid crystal element is added for intensity control, then crosstalk deterioration is prevented, but device size and cost increase
Solution Approach 1:
The patent makes the liquid crystal diffraction element multi-functional by designing it to simultaneously perform both wavelength demultiplexing and intensity control functions. The liquid crystal material's ability to modulate both the phase and amplitude of light allows a single element to replace what would traditionally require separate components, thereby maintaining crosstalk control while reducing device complexity.
Solution Approach 2:
The patent merges the deflection control function and intensity control function into a single liquid crystal diffraction element. By integrating these functions that were previously separated in conventional designs, the patent achieves the same crosstalk performance without requiring additional liquid crystal elements, thus reducing device size and simplifying the overall structure.
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 proposed configuration effectively reduces crosstalk and achieves miniaturization of wavelength selective switches, improving their performance and reducing device size and cost by efficiently demultiplexing and deflecting light without the need for additional liquid crystal elements.
Implementation Method 1
a dispersive element that demultiplexes wavelength-multiplexed light incident from the input ports; wherein the dispersive element is a liquid crystal diffraction element
Implementation Method 2
a liquid crystal diffraction element having a liquid crystal alignment pattern where an orientation of an optical axis derived from a liquid crystal compound changes while continuously rotating
Implementation Method 3
a polarization controller that adjusts a polarization state of light incident from the input ports
Data Source
AI summary
Provided is a wavelength selective switch where crosstalk is improved and miniaturization is realized. The wavelength selective switch includes: one or more input ports; one or more output ports; a polarization controller that adjusts a polarization state of light incident from the input ports; a dispersive element that demultiplexes wavelength-multiplexed light incident from the input ports; and a deflection element that controls deflection of the demultiplexed light. The dispersive element is a liquid crystal diffraction element having a liquid crystal alignment pattern where an orientation of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction.