Wavelength Separated Fine Steering Assembly for Optical Isolation
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Solution Overview
Problem
Free space optical communication systems face challenges in achieving high isolation between transmit and receive channels due to extreme power differences, leading to crosstalk and degradation in communication performance, especially over long distances, and existing solutions like separate optical paths or polarization separation are costly, complex, and limited in isolation capabilities.
Innovation Solution
An optical communication system with a terminal configured to operate in both full duplex modes using dichroic reflectors for wavelength separation and a fine steering module, allowing the terminal to switch between transmit and receive functions without mechanical switching, maintaining a stable optical path and providing high isolation through wavelength separation and polarization control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate optical paths are used for transmit and receive channels, then isolation between channels is improved, but device complexity and cost increase
Solution Approach 1:
The optical path is segmented into transmit and receive channels using dichroic reflectors that separate wavelengths. The transmit beam at wavelength λ1 and receive beam at wavelength λ2 are spatially separated through the dichroic reflector arrangement, allowing high isolation while sharing common optical components like the telescope and steering mirrors.
Solution Approach 2:
The patent introduces wavelength as an additional dimension for signal separation. By operating at different wavelengths (λ1 for transmit, λ2 for receive) and using dichroic reflectors to manipulate these wavelengths spatially, the system achieves channel isolation without requiring physically separate optical paths, thus reducing complexity.
2Reliability
If wavelength separated fine steering assembly is used, then isolation between transmit and receive signals is improved, but device complexity increases
Solution Approach 1:
The dichroic reflectors serve multiple functions: they separate transmit and receive wavelengths, enable full-duplex operation, and maintain a stable optical path. The fine steering module also serves dual purposes for both transmit and receive beams, reducing the need for separate components and offsetting the added complexity of wavelength separation.
Solution Approach 2:
The dichroic reflector acts as an intermediary element that mediates between the transmit and receive channels. It selectively reflects or transmits different wavelengths, enabling high isolation while allowing both channels to share common optical infrastructure. The fine steering module similarly mediates beam direction for both wavelengths.
3Productivity
If full duplex communication is implemented, then communication efficiency is improved, but isolation requirements become more stringent
Solution Approach 1:
The system changes the wavelength parameter to achieve full-duplex operation with high isolation. By transmitting at wavelength λ1 and receiving at wavelength λ2 simultaneously, the dichroic reflectors can provide the necessary isolation (e.g., 70 dB or higher) while enabling continuous two-way communication, thus improving productivity without compromising reliability.
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 isolation between transmit and receive signals, reducing crosstalk and maintaining communication integrity over long distances, while simplifying inventory management and enabling adaptable terminal pairing without moving parts, thus enhancing communication reliability and efficiency.
Implementation Method 1
a first dichroic reflector configured to substantially reflect a first wavelength, pass a portion of the first wavelength, and pass a second wavelength; a second dichroic reflector configured to substantially pass the second wavelength, reflect a portion of the second wavelength, and reflect the first wavelength
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An optical communication system that includes terminals that operate with different, widely separated wavelengths in which a terminal in the system may be configured to function in both a first operational mode and in a second operational mode. For example, a terminal according to the techniques of this disclosure may communicate with full duplex communication by transmitting a first optical wavelength and receiving a second optical wavelength while in the first operational mode. The same terminal may be reconfigured to transmit the second optical wavelength and receive the first optical wavelength while in the second operational mode. In some examples, the terminal may be located in a spacecraft, such as an orbiting satellite or other vehicle, and may communicate with other terminals such as airborne terminals, terminals located at ground station on the Earth's surface, or with terminals located in other spacecraft.