Tunable Beamsplitter for Full-Duplex Free-Space Laser Communication
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Solution Overview
Problem
Free-space laser communication systems face challenges such as atmospheric turbulence, cloud obscurations, and compatibility with moving platforms, leading to performance issues and inability to achieve full-duplex operation in network contexts due to misalignments and lack of eye-safe wavelengths.
Innovation Solution
A free-space communication transceiver architecture that uses a tunable beamsplitter and wavelength-switchable data laser transmitter and receiver modules, allowing for collinear transmission and reception of laser beams along a common optical axis, with randomly polarized beams and eye-safe wavelengths, enabling full-duplex operation and integration with RF signals for backup communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static wavelengths and polarizations are employed in laser communication systems, then system simplicity is maintained, but full-duplex operation and network flexibility are lost
Solution Approach 1:
The patent implements dynamic wavelength and polarization tuning capabilities in the laser transmitter and receiver modules. The laser transmitter can be tuned to different wavelengths and polarizations, and the receiver can be tuned to receive at different wavelengths and polarizations. This dynamic adaptability enables full-duplex operation where transmitter and receiver can operate simultaneously at different wavelengths, resolving the contradiction between system simplicity and operational flexibility.
Solution Approach 2:
The system changes operational parameters (wavelength and polarization state) dynamically based on communication requirements. By varying these parameters, the system achieves full-duplex capability and network flexibility without requiring complex physical reconfiguration, thus improving adaptability while managing device complexity through parameter-based control rather than structural complexity.
2Reliability
If collinear beam transmission is used to reduce misalignment sensitivity, then robustness to environmental factors is improved, but system flexibility for network operation is reduced
Solution Approach 1:
The patent combines collinear beam transmission for reliability with dynamic wavelength and polarization tuning for flexibility. The collinear arrangement provides robustness to misalignments and environmental factors, while the dynamic tuning of wavelengths and polarizations enables the system to adapt to different network communication scenarios, thus resolving the contradiction between reliability and flexibility.
Solution Approach 2:
The system achieves universality by making the same collinear transmission infrastructure capable of supporting multiple functions: reliable single-mode communication and flexible multi-mode network operation. The wavelength and polarization tuning capabilities allow a single collinear system to serve multiple communication purposes, eliminating the need for separate systems for reliability and flexibility.
3Productivity
If non-eye-safe laser wavelengths are used to achieve higher data rates, then communication performance is improved, but safety and practical deployment are worsened
Solution Approach 1:
The patent changes the wavelength parameter to use eye-safe regions (such as 1550 nm or higher) while maintaining high data rates through advanced modulation techniques and wavelength division multiplexing. This parameter change resolves the contradiction by selecting wavelengths that are both safe for human eyes and capable of supporting high-speed communication, eliminating the need to sacrifice safety for performance.
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 solution enhances the robustness and flexibility of free-space laser communication systems, reducing sensitivity to environmental factors and misalignments, enabling reliable full-duplex operation in moving platform environments and supporting network communication among multiple terminals.
Implementation Method 1
the beamsplitter is substantially transmissive at one of the first and second wavelengths and substantially reflective at the other of the first and second wavelengths
Implementation Method 2
a beamsplitter that directs the transmit laser beam from the data laser transmitter module to the telescope and directs the receive laser beam from the telescope to the optical receiver module
Implementation Method 3
The beamsplitter can be, for example, a tunable etalon filter that is coupled to the transmit laser path along a first optical axis and coupled to the receive laser path along a second optical axis, such that the etalon filter is substantially transmissive to one of the transmit and receive laser beams and substantially reflective to the other of the transmit and receive laser beams
Implementation Method 4
a data laser transmitter module for generating a transmit laser beam modulated with data
Implementation Method 5
the data laser transmitter module is tunable such that the transmit wavelength of the transmit laser beam is selectable between at least first and second wavelengths
Implementation Method 6
an optical receiver module for processing a receive laser beam to recover data
Implementation Method 7
the optical receiver module is tunable such that the receive wavelength of the receive laser beam is selectable between at least the first and second wavelengths
Implementation Method 8
a telescope for transmitting and receiving laser beams
Implementation Method 9
the transmit and receive laser beams travel along a common optical axis as collinear, collimated free-space beams
Data Source
AI summary
A free-space communication transceiver includes a telescope for transmitting and receiving laser beams, a tunable laser transmitter for generating a transmit laser beam modulated with data, a tunable optical receiver for processing a receive laser beam received from the telescope to recover data, and a tunable beamsplitter that directs the transmit laser beam to the telescope and directs the receive laser beam from the telescope to the optical receiver. Between the telescope and beamsplitter, the transmit and receive laser beams travel along a common optical axis as collinear collimated free-space beams. The transmit and receive laser beams operate at different wavelengths that can be interchanged, thereby support full-duplex operation. The beamsplitter employs a tunable etalon filter whose wavelength-dependent transmission characteristics are adjusted according to the transmit and receive wavelengths. Optionally, RF signals can additionally be couple to the common optical axis and transmitted and received by the telescope.