Distributed Optical Millimeter Wave Terahertz Transfer System
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Solution Overview
Problem
Current optical millimeter wave frequency transfer technologies are limited to point-to-point applications and lack a distributed solution, which is necessary for advanced applications like the Atacama Large Millimeter Array (ALMA) and Very Long Baseline Interferometry (VLBI), requiring a method to transfer stable millimeter wave/terahertz signals over long distances with high precision and reliability.
Innovation Solution
A distributed optical millimeter wave terahertz transfer system is developed, utilizing a local terminal, transfer link, and user terminal with components like optoisolators, Faraday rotators, acousto-optic frequency shifters, and photovoltaic conversion units to extract and filter optical signals, achieving phase noise compensation without synchronization of local reference sources and inhibiting backward scatter noises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If point-to-point optical millimeter wave transfer is used, then the system structure is simple, but the application range is limited and cannot meet distributed array requirements
Solution Approach 1:
The transfer link is segmented into multiple distributed nodes (local terminal, user terminal, and intermediate access terminals) that can independently extract and utilize millimeter wave signals. Each node functions as an independent signal source, enabling the system to support distributed array applications while maintaining manageable complexity at each node.
Solution Approach 2:
The optical carrier wave serves multiple functions simultaneously: it carries millimeter wave signals to multiple users, provides phase reference for synchronization, and enables bidirectional communication. This multi-functionality allows a single optical fiber link to support diverse distributed applications without requiring separate dedicated channels for each function.
2Measurement precision
If traditional satellite link based frequency transfer is used, then the system is simple to implement, but the precision is insufficient due to atmosphere turbulence
Solution Approach 1:
Optical fiber serves as an intermediary medium that replaces the satellite link for frequency and phase transfer. The optical fiber shielded environment eliminates atmosphere turbulence effects while maintaining the ability to transfer high-stability frequency references, achieving superior precision without excessive complexity through standardized optical fiber infrastructure.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic satellite transmission system with an optical fiber-based system. This substitution eliminates the vulnerability to atmosphere turbulence while leveraging the established optical fiber infrastructure, achieving high precision frequency and phase transfer with practical implementation complexity.
3Adaptability or versatility
If optical signals are extracted at multiple positions in the transfer link, then distributed signal availability is achieved, but backward scatter noises increase
Solution Approach 1:
The system performs preliminary phase compensation at each access terminal before signal extraction using the retrieved phase information. This preliminary action corrects phase errors introduced by the optical fiber link and backward scatter effects, ensuring that distributed signal extraction does not compromise signal quality despite the presence of backward scatter noises.
Solution Approach 2:
The system implements feedback by retrieving the phase of the optical signal at each access terminal and using this information to compensate for phase errors in subsequent signal processing. This feedback mechanism actively counteracts the harmful effects of backward scatter noises, enabling clean signal extraction at multiple distributed positions.
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 phase compensation with an unlimited compensation range and high reliability, providing stable millimeter wave signals at any position in the transfer link through optical and microwave filtering, and frequency division, with a simple structure and low implementation cost.
Implementation Method 1
an optoisolator unit (10), a first optical coupler (11), a first Faraday rotator mirror (12)
Implementation Method 2
a first acousto-optic frequency shifter (16), a second acousto-optic frequency shifter (18)
Implementation Method 3
a first photovoltaic conversion unit (22), a second photovoltaic conversion unit (23)
Implementation Method 4
a first optical filter (14), a second optical filter (15)
Implementation Method 5
a first Faraday rotator mirror (12), a second Faraday rotator mirror (33)
Data Source
AI summary
An optical millimeter wave terahertz transfer system and transfer method are disclosed. The device comprises a local terminal, a transfer link, an access terminal, and a user terminal. By using the device in the transfer link, optical signals transferred forward and backward are extracted through optical couplers, and millimeter wave terahertz signals with a stable phase are obtained at any position in the transfer link through optical signal filtering, photovoltaic conversion, microwave filtering, frequency division and optical frequency shift processing. The device and method have the characteristics of high reliability, simple structure, and low implementation cost.