Polarisation-independent, optical multiplexing and demultiplexing systems based on ferroelectric liquid crystal phase modulators for spatial mode division multiplexing and demultiplexing
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Solution Overview
Problem
Current optical communication systems face limitations in data capacity, particularly in single mode fibers, and existing methods for optical spatial mode division multiplexing are either complex, bulky, or non-reconfigurable, hindering efficient data encoding and transmission.
Innovation Solution
A reconfigurable optical spatial mode multiplexing and demultiplexing system utilizing a polarisation-independent, controllably reconfigurable phase modulator, such as a ferroelectric liquid crystal spatial light modulator, to convert spatial modes between lower and higher orders, enabling efficient data encoding and decoding in multimode fibers without the need for separate polarisation components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static optical mode division multiplexing is used, then the system structure is simple, but the system is not reconfigurable and cannot adapt to different spatial mode conversions
Solution Approach 1:
The patent employs dynamic spatial light modulators (SLMs) that can be reconfigured through software control to perform different spatial mode conversions. The SLMs can dynamically change their phase profiles to convert between various lower and higher order spatial modes, providing reconfigurability without requiring multiple fixed optical components for each mode conversion scenario.
Solution Approach 2:
The patent uses universal spatial light modulators that can perform multiple spatial mode conversion functions through software control. A single SLM device can be reconfigured to perform different mode conversions (e.g., LP01 to LP11, LP01 to LP21, etc.) by loading different phase profiles, replacing the need for multiple dedicated static optical components.
2Adaptability or versatility
If computerised hologram techniques are used for mode division multiplexing, then spatial mode conversion is achieved, but the system becomes complex and bulky
Solution Approach 1:
The patent extracts the complex holographic processing functionality and implements it through software control of spatial light modulators, removing the need for bulky physical holographic components. The phase modulation patterns that would traditionally require complex holographic optical elements are instead generated and controlled through computational algorithms.
Solution Approach 2:
The patent replaces physical mechanical holographic components with software-controlled spatial light modulators. Instead of using fixed holographic optical elements that require precise mechanical alignment and occupy significant space, the system uses programmable phase modulators controlled by computer algorithms, significantly reducing system complexity and size.
3Ease of operation
If separate polarisation components are used for spatial mode conversion, then polarisation-specific control is achieved, but the system complexity increases and polarisation independence is lost
Solution Approach 1:
The patent applies local quality modification through spatially varying phase profiles imposed by the SLMs. Different regions of the optical beam receive different phase adjustments tailored to achieve the desired spatial mode conversion, while maintaining overall polarisation independence. The phase modulation is applied locally across the beam cross-section rather than requiring separate handling of polarisation components.
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
This solution enhances data capacity and transmission efficiency by allowing flexible mode conversion and routing, optimizing spatial mode usage in optical communication systems, and can be implemented in a compact and efficient manner.
Implementation Method 1
a phase modulator to impose a phase profile on an input beam to convert a spatial mode order of the input beam from a lower order spatial mode to a higher order spatial mode
Implementation Method 2
A reconfigurable optical spatial mode multiplexing and demultiplexing system utilizing a polarisation-independent, controllably reconfigurable phase modulator, such as a ferroelectric liquid crystal spatial light modulator
Data Source
AI summary
We describe a multimode reconfigurable optical spatial mode multiplexing system having first and second first and second input beams and a beam combiner to combine these into an optical output. At least one of the paths comprises a polarisation-independent reconfigurable phase modulator to impose a controllable phase profile on an input beam in an input beam phase modulating optical path, to controllably convert a spatial mode order of the input beam from a lower to a higher order spatial mode. The system also has a control input to control the phase modulator to configure the phase profile for the mode conversion. The input beams are combined into a multiple spatial mode combined beam output independent of a polarisation of the input beams. The number of spatial modes of the combined beam can be more than a number of spatial modes in either of the first and second input beams separately.