Liquid Crystal Grating Optical Switch Assembly
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Solution Overview
Problem
Existing optical cross connection (OXC) systems based on liquid crystal (LC) and polarization beam splitter (PBS) arrays face difficulties in assembly, have a large volume, and high costs, limiting their effectiveness in high-speed and large-capacity communications networks.
Innovation Solution
A liquid crystal grating-based optical switch is implemented using an N×N liquid crystal grating array with input and output quarter-wave plates and polarization beam splitters, allowing for switchable polarization control and efficient optical cross interconnection by selecting transmission paths with voltage settings, thereby simplifying the apparatus, reducing size, and lowering costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an optical cross connection is based on an LC array and a PBS array, then optical signal routing is achieved, but assembly difficulty increases, volume becomes large, and costs become high
Solution Approach 1:
The patent combines the liquid crystal array and polarization beam splitter array into a single integrated liquid crystal grating module. The liquid crystal grating is formed by patterning the liquid crystal alignment layer with groove structures, merging what were previously separate components (LC cells and PBS optics) into one unified device that performs both polarization control and beam steering functions
Solution Approach 2:
The liquid crystal grating serves multiple functions simultaneously: it acts as a polarization controller, a beam steering element, and a switching matrix. By applying different voltages to different regions of the liquid crystal grating, the device can route optical signals between multiple input and output ports while also controlling polarization states, replacing what previously required multiple separate components
2Device complexity
If an optical cross connection is based on an LC array and a PBS array, then optical signal routing is achieved, but the device volume becomes large
Solution Approach 1:
The patent combines the liquid crystal array and polarization beam splitter array into a single integrated liquid crystal grating module. The liquid crystal grating is formed by patterning the liquid crystal alignment layer with groove structures, merging what were previously separate components (LC cells and PBS optics) into one unified device that performs both polarization control and beam steering functions
Solution Approach 2:
The liquid crystal molecules are nested within the grooved alignment layer structure, creating a compact configuration where the functional elements are embedded within each other rather than arranged as separate bulk components. This nested arrangement significantly reduces the overall device volume while maintaining the necessary optical functions
3Device complexity
If an optical cross connection is based on an LC array and a PBS array, then optical signal routing is achieved, but costs become high
Solution Approach 1:
The patent combines the liquid crystal array and polarization beam splitter array into a single integrated liquid crystal grating module. The liquid crystal grating is formed by patterning the liquid crystal alignment layer with groove structures, merging what were previously separate components (LC cells and PBS optics) into one unified device that performs both polarization control and beam steering functions
Solution Approach 2:
The patent replaces complex mechanical assembly of multiple optical components with a simplified fabrication process using photolithography and UV curing to pattern the liquid crystal alignment layer. This substitution of mechanical assembly with optical/fabrication processes reduces both manufacturing complexity and cost
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 enables efficient optical cross switching and add/drop multiplexing functions with improved assembly simplicity, reduced size, and lower costs, addressing the limitations of previous OXC systems.
Implementation Method 1
receive the circularly polarized light from the input quarter-wave plate by using a liquid crystal grating that is in the N×N liquid crystal grating array and that is corresponding to the input quarter-wave plate
Implementation Method 2
A polarization direction of the light on each node is controlled by controlling a voltage of the LC array
Implementation Method 3
controlling a polarization direction of the light by controlling a voltage of the LC array
Implementation Method 4
couple the two optical signals having different polarization directions into circularly polarized light
Implementation Method 5
split an input optical signal from the input collimator into two optical signals having different polarization directions
Data Source
AI summary
Embodiments of the present invention provide a liquid crystal grating-based optical switching apparatus, including an input collimator, an input polarization beam splitter, an input quarter-wave plate, a liquid crystal grating, an output quarter-wave plate, an output polarization beam splitter, and an output collimator. A transmission path is selected for an optical signal by changing a voltage of a liquid crystal grating so that the optical signal is output to a selected output.