Asymmetric OAM Optical Wireless System for Uplink Capacity
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Solution Overview
Problem
Conventional free space optical wireless communication systems suffer from high costs, bulkiness, and low uplink transmission capacity due to symmetrical architecture and energy attenuation, especially with traditional orbital angular momentum (OAM) multiplexers using multiple beam splitters and spatial light modulators.
Innovation Solution
An asymmetric bidirectional optical wireless communication system utilizing polarizing beam splitters to separate and combine light sources, an orbital angular momentum multiplexer with beam homogenizers to enhance uplink capacity, and a spatial light modulator for data modulation, reducing energy consumption and system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a symmetrical architecture with light emitters and photodetectors at both ends is used, then bidirectional communication is achieved, but the client end device becomes bulky and costly
Solution Approach 1:
The patent applies asymmetry by designing different functional architectures for the system end device and client end device. The system end device includes complete bidirectional components (light emitter, photodetector, modulators), while the client end device only includes a photodetector and spatial light modulator, eliminating the need for light emitters at the client end and reducing complexity and portability requirements.
Solution Approach 2:
The patent implements multi-functionality through the system end device that can both transmit and receive signals using shared optical paths and components. The light emitter serves both uplink and downlink directions, and the polarization beam splitters enable the same optical path to handle multiple communication functions, reducing the need for separate dedicated components at each end.
2Productivity
If traditional OAM multiplexer with multiple beam splitters and spatial light modulators is used, then high data transmission rate is achieved, but optical energy is severely attenuated
Solution Approach 1:
The patent extracts and eliminates the beam splitter component from the OAM multiplexer architecture. Instead of using multiple beam splitters to combine OAM beams, the invention directly couples multiple OAM beams using spatial light modulators and optical lenses, removing the energy-lossy beam splitting and recombining stages while maintaining high data transmission rates through parallel OAM channel multiplexing.
Solution Approach 2:
The patent introduces spatial light modulators as intermediary devices that directly manipulate and couple OAM beams without requiring beam splitters. The spatial light modulators serve as mediators that can independently control phase and amplitude of multiple OAM modes, enabling efficient beam combination and coupling while minimizing optical energy loss throughout the transmission path.
3Productivity
If polarizing beam splitter is used to separate uplink and downlink light sources, then transmission channel capacity is increased, but system complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing polarization state as a distinguishing parameter to separate uplink and downlink communication channels. The polarizing beam splitters divide light based on polarization orientation (P-polarization for uplink, S-polarization for downlink), enabling dual-directional communication through a single optical path without requiring physically separate channels, thus increasing capacity while managing complexity through parameter-based differentiation.
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 system achieves high uplink data capacity with low energy consumption and cost, improving transmission rates to over 3.6 Gb/s and reducing system size, while maintaining efficient downlink transmission.
Implementation Method 1
a polarizing beam splitter arranged on a path of the first incident beams for splitting the first incident beams into downlink light beams and uplink light beams
Implementation Method 2
an orbital angular momentum multiplexer arranged on a path of the uplink light beams for processing orbital angular momentum modulation on the uplink light beams
Implementation Method 3
a second spatial light modulator arranged on the path of the orbital angular momentum beams for data modulation on the orbital angular momentum beams
Implementation Method 4
a demultiplexer arranged on a path of orbital angular momentum beams for demodulating the orbital angular momentum beams which are then received by a second photodetector
Data Source
AI summary
An asymmetric bidirectional optical wireless communication system based on orbital angular momentum comprises a system end device and a client end device. The system can split light into P-polarization beam and S-polarization beam, and utilize the orbital angular momentum multiplexing technology to increase the system capacity for uplink transmission in the client end device. In addition, the system also uses the combination of a beam homogenizer and a spatial light modulator to design an orbital angular momentum multiplexer with low energy loss, which can increase the number of orbital angular momentum channels by increasing the effective area of the components.