Mode Division Multiplexing Using Spatial Modulators
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Solution Overview
Problem
In optical data transmission using Mode Division Multiplexing, existing technologies face challenges in aligning mode patterns for demultiplexing and multiplexing, leading to signal component misalignment and differential mode group delay issues, which affect data rate and transmission distance.
Innovation Solution
The method involves demultiplexing and multiplexing incoming optical signals with specific azimuthal and radial orders, ensuring orthogonality and matching mode patterns to facilitate linear transformation and compensate for differential mode group delays, using optical spatial modulators with corresponding multiplicative patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mode patterns are aligned for demultiplexing and multiplexing, then signal component alignment is improved, but device complexity and orientation precision requirements increase
Solution Approach 1:
The patent introduces an intermediary transformation process that converts higher-order mode patterns into fundamental mode patterns during demultiplexing, and then reconstructs the desired higher-order modes during multiplexing. This intermediary fundamental mode acts as a reference that simplifies the alignment process, eliminating the need for direct higher-order mode pattern matching between transmitter and receiver.
Solution Approach 2:
The patent segments the mode division multiplexing process into distinct demultiplexing and multiplexing stages. At the receiver, incoming higher-order modes are first demultiplexed into separate fundamental modes, processed individually, and then remultiplexed back to higher-order modes for transmission. This segmentation allows each stage to operate with simplified alignment requirements.
2Productivity
If higher-order modes are used for Mode Division Multiplexing, then data rate is improved, but differential mode group delay increases affecting transmission distance
Solution Approach 1:
The patent dynamically changes the mode parameters (azimuthal order and radial order) of optical signals during transmission. By transforming signals between different mode orders and combining them with fundamental modes, the system optimizes the differential mode group delay characteristics to extend transmission distance while maintaining high data rates through mode division multiplexing.
Solution Approach 2:
The patent creates composite mode structures by combining higher-order modes with fundamental modes in specific configurations. This composite approach balances the high capacity of higher-order modes with the lower delay characteristics of fundamental modes, achieving both high data rates and extended transmission distances.
3Manufacturing precision
If exact orientation alignment of mode patterns is required, then signal integrity is improved, but manufacturing and alignment precision requirements increase
Solution Approach 1:
Instead of requiring the receiver to match the transmitter's higher-order mode orientations, the patent inverts the approach by transforming all incoming higher-order modes into fundamental modes at the receiver. This fundamental mode transformation is orientation-independent, eliminating the need for precise orientation alignment between transmitter and receiver 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 approach ensures proper transformation of all signal components and compensates for differential mode group delays, maintaining data integrity and extending transmission distance by averaging delays, without requiring exact orientation alignment of mode patterns.
Implementation Method 1
A plurality of incoming optical signals having respective incoming waveguide modes are demultiplexed from an incoming optical multi-mode fiber into respective intermediate optical signals having essentially a fundamental waveguide mode. The step of demultiplexing is carried out using respective first optical spatial modulators, whose multiplicative patterns correspond to the electrical field patterns of the incoming waveguide modes.
Implementation Method 2
The intermediate optical signals are multiplexed into respective outgoing optical signals having respective outgoing waveguide modes within an outgoing optical multi-mode fiber. The step of multiplexing is carried out using respective second optical spatial modulators, whose multiplicative patterns correspond to the electrical field patterns of the outgoing waveguide modes.
Implementation Method 3
The steps of demultiplexing and multiplexing are carried out, such that a first incoming optical signal, whose respective first incoming waveguide mode is of an azimuthal order equal to zero, results essentially in such a first outgoing optical signal, whose respective first outgoing waveguide mode is of an azimuthal order equal to zero. Furthermore, the steps of demultiplexing and multiplexing are carried out, such that two second incoming optical signals, whose respective second incoming waveguide modes are of a same azimuthal order greater than zero, of a same radial order, and orthogonal to each other result essentially in such respective second outgoing signals, whose respective second outgoing waveguide modes are of a same azimuthal order greater than zero, of a same radial order, and also orthogonal to each other.
Data Source
AI summary
A method and a device for optical data transmission are proposed. Incoming optical signals having respective incoming waveguide modes are mapped into outgoing optical signals having respective outgoing waveguide modes, using optical spatial modulators, whose multiplicative patterns correspond to the respective electrical field patterns of the respective incoming or outgoing waveguide modes. An incoming optical signal, whose respective incoming waveguide mode is of an azimuthal order equal to zero, results in an outgoing optical signal, whose respective outgoing waveguide mode is of an azimuthal order equal to zero. Furthermore, two incoming optical signals, whose respective second incoming waveguide modes are of a same azimuthal order greater than zero, of a same radial order, and orthogonal to each other result in respective outgoing signals, whose respective outgoing waveguide modes are off a same azimuthal order greater than zero, of a same radial order and orthogonal to each other.