Wavelength Selective Switch LCOS Polarization Crosstalk
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Solution Overview
Problem
Wavelength selective switches (WSS) using liquid crystal on silicon (LCOS) phase arrays experience unexpected crosstalk between ports due to attenuation control, leading to leakage of attenuated beams into unintended neighboring ports.
Innovation Solution
A wavelength selective switch apparatus incorporating a polarization modulation element with a multi-pixel liquid crystal phase array and a polarizer, optically matched with an LCOS phase array, which controls light beams by adjusting voltage and polarization to selectively divert wavelength components, thereby preventing crosstalk by attenuating or blocking input light beams and steering output beams for port switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If attenuation control is implemented using LCOS phase array functionalities, then beam attenuation is achieved, but crosstalk between ports occurs causing leaked beams to enter unintended neighboring ports
Solution Approach 1:
The patent divides the attenuation function into two separate components: a polarization modulation element (PME) that controls polarization state and a polarizer that performs the actual attenuation. This segmentation allows the PME to modulate without causing crosstalk, while the polarizer provides clean attenuation by blocking specific polarization components, thus eliminating the harmful leakage effect.
Solution Approach 2:
The patent introduces a polarizer as an intermediary element between the PME and the optical output. The polarizer acts as a mediator that converts the polarization modulation into intensity modulation without allowing energy leakage to adjacent ports, thereby resolving the crosstalk issue while maintaining attenuation functionality.
2Device complexity
If a single LCOS phase array is used for both polarization control and attenuation, then device complexity is reduced, but switching precision deteriorates due to dynamic crosstalk during port transitions
Solution Approach 1:
The patent segments the switching module into distinct functional units: a polarization modulation element for polarization control and a polarizer for attenuation. This segmentation allows each element to perform its specialized function with high precision, eliminating the dynamic crosstalk that occurs when a single element attempts to perform both functions simultaneously.
Solution Approach 2:
The polarization modulation element and polarizer work in a self-service manner where the PME prepares the polarization state and the polarizer independently performs the attenuation. This functional independence ensures that each element operates optimally without interfering with the other, maintaining high switching precision during port transitions.
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 effectively reduces or eliminates crosstalk between ports, ensuring accurate beam steering and attenuation, maintaining high switching precision without dynamic crosstalk during port transitions.
Implementation Method 1
a polarization modulation element that includes an array of a plurality of liquid crystal (LC) pixels
Implementation Method 2
controlling a voltage applied thereto and/or a polarization of the light beams
Implementation Method 3
a polarizer that is configured to attenuate the input light beams output from the polarization modulation element and allow only a desired polarization of the input light beams to enter a steering element
Implementation Method 4
the steering element that includes an array of a plurality of liquid crystal on silicon (LCOS) pixels
Implementation Method 5
accurate control of the output angle of the beams can be realized
Data Source
AI summary
A wavelength selective switch (WSS) apparatus. The WSS apparatus includes: a plurality of optical ports configured to emit input light beams to a switching module and receive output light beams from the switching module; and the switching module configured to receive the input light beams, select, according to a wavelength component of the input light beams, at least one of the plurality of optical ports to which the output light beams of the wavelength component are to propagate, and output the output light beams of the wavelength component to the selected at least one optical port, the switching module comprising: a polarization modulation element including an array of a plurality of liquid crystal (LC) pixels; a polarizer; and a steering element including an array of a plurality of liquid crystal on silicon (LCOS) pixels.