OAM Beam Multiplexing for High-Capacity THz Links
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Solution Overview
Problem
Current telecommunications systems face challenges in transmitting large quantities of data at high speeds while maintaining reliability, especially in diverse physical and environmental conditions, and there is a lack of effective methods for combining orbital-angular momentum (OAM) multiplexing with frequency-division-multiplexing (FDM) and polarization-division-multiplexing (PDM) for high-capacity, free-space THz links.
Innovation Solution
The system employs mode-division-multiplexing (MDM) using OAM beams, which are generated and modulated to carry multiple data channels, and then transmitted and received using phase transformers and spiral phase plates, allowing for efficient multiplexing and demultiplexing with minimal crosstalk, thereby increasing data capacity and spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple data channels are transmitted using conventional methods, then data capacity is limited, but increasing data capacity requires more complex transmission systems
Solution Approach 1:
The patent extends the transmission dimension by utilizing the spatial mode dimension through OAM beams. Instead of only using frequency or time dimensions for multiplexing, the system incorporates radial and azimuthal mode indices (p, l) to create additional independent channels. This allows multiple data channels to be transmitted simultaneously through different spatial modes of optical beams, significantly increasing data capacity without proportionally increasing system complexity.
Solution Approach 2:
The system changes the transmission parameters by using different OAM mode parameters (radial index p and azimuthal index l) to distinguish multiple data channels. Each channel is assigned a unique combination of mode parameters, allowing the system to multiplex multiple channels by varying these spatial mode parameters rather than requiring separate physical transmission paths or complex frequency management.
2Productivity
If OAM multiplexing is implemented to increase data capacity, then spectral efficiency improves, but crosstalk between channels increases
Solution Approach 1:
The patent applies local quality by assigning different spatial mode distributions to different data channels. Each OAM mode has a unique intensity and phase distribution in the spatial domain, allowing receivers to distinguish between channels through mode decomposition. This localized spatial differentiation enables high spectral efficiency while maintaining low crosstalk, as each channel occupies a distinct spatial mode signature that can be independently detected and separated at the receiver.
3Speed
If high-speed wireless communication is achieved through optical beam transmission, then data rate increases to tens of Gbit/s, but system complexity and alignment precision requirements increase
Solution Approach 1:
The system achieves multi-functionality by using a single optical transmission medium to simultaneously carry multiple data channels through different OAM modes. Instead of requiring separate transmission paths or complex MIMO antenna arrays, the patent uses one optical beam carrier that can encode multiple channels through spatial mode multiplexing. This universal approach simplifies the overall system architecture while maintaining high data rates, as the same hardware infrastructure supports multiple channels without requiring additional alignment precision for each separate path.
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 enables high-speed wireless communication with data rates of tens of gigabits per second, achieving efficient multiplexing of multiple data channels with low crosstalk and improved bit-error-rate performance, thereby enhancing the bandwidth and reliability of THz communication systems.
Implementation Method 1
an optical fiber operatively coupled with the first beam generator and the beam modulator to convert the first beam and the second beam into a third beam including the data and having a third frequency based on a difference between the first frequency and the second frequency
Implementation Method 2
a phase transformer operatively coupled with the photodiode to transform the third beam into a fourth beam having a first angular distribution and including a first portion of the data, and into a fifth beam having a second angular distribution corresponding to the first angular distribution and including a second portion of the data
Data Source
AI summary
Aspects of this technical solution are directed to multiplexed transmission by optical beam transmission. A method can include generating a first beam having a first frequency in an optical frequency range, generating a second beam including data and having a second frequency in the optical frequency range, converting the first beam and the second beam into a third beam including the data and having a third frequency based on a difference between the first frequency and the second frequency, and transforming the third beam into a fourth beam having a first angular distribution and including a first portion of the data, and into a fifth beam having a second angular distribution corresponding to the first angular distribution and including a second portion of the data.