Spatial Mode Multiplexing for Duplex Optical Links Without Beam Steering
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Solution Overview
Problem
Establishing a duplex optical communication link between terminals separated by a large distance is challenging due to the need for beam steering with moving parts, which increases system mass, power consumption, and requires different wavelengths/polarizations for transmit and receive signals, limiting techniques like wavelength division multiplexing.
Innovation Solution
A system configured with a multi-mode fiber and a phase plate array to decouple optical beam modes, enabling co-linear transmission and reception without moving parts, allowing for higher signal throughput and enabling wavelength division multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beam steering with moving parts is used to establish duplex optical communication links, then the communication link can be established between terminals, but the system mass, power consumption, and complexity increase
Solution Approach 1:
The patent extracts and eliminates the moving parts (beam steering mechanisms) from the system by using a static optical architecture with multi-mode fibers and phase plate arrays to achieve mode decomposition and multiplexing, thereby reducing system mass and complexity while maintaining communication functionality
Solution Approach 2:
The patent segments the optical beam into multiple spatial modes using a phase plate array, which then can be independently managed and transmitted through separate single-mode fibers, eliminating the need for complex beam steering to manage multiple signals
2Reliability
If beam steering with moving parts is used for duplex communication, then transmit and receive signals can be separated, but different wavelengths and polarizations are required, limiting multiplexing techniques
Solution Approach 1:
The patent transitions from wavelength/polarization domain separation to spatial mode domain separation by using a phase plate array to decompose the optical beam into multiple spatial modes, which can then be transmitted through separate fibers without requiring different wavelengths or polarizations, thereby enabling WDM and other multiplexing techniques
3Reliability
If single-mode fibers are used for optical communication, then signal quality is maintained, but the numerical aperture is limited, reducing signal throughput
Solution Approach 1:
The patent merges multiple single-mode fibers into a parallel transmission system, each carrying a different spatial mode, thereby achieving high signal throughput while maintaining signal quality in each individual fiber channel. The phase plate array enables this by efficiently coupling multiple modes into separate single-mode fibers
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
Reduces system components, mass, and power consumption while enabling improved information transfer and techniques like WDM, providing a more efficient and compact optical communication solution.
Implementation Method 1
a phase plate array configured to decouple the multiple modes of an optical beam exiting the multi-mode fiber to a fundamental optical mode of the optical beam and to a plurality of higher-order optical modes
Implementation Method 2
the first single-mode fiber is coupled to both the signal transmitting path and the signal receiving path using an optical circulator
Data Source
AI summary
An optical system includes an optical transmitter coupled to a signal transmitting path, an optical receiver coupled to a signal receiving path, and a phase plate array configured to couple a first portion of an optical beam to a first single-mode fiber and to couple other portions of the optical beam to a plurality of other single-mode fibers. The first portion of the optical beam corresponds to a fundamental optical mode and the other portions corresponds to a plurality of higher-order optical modes. The first single-mode fiber is coupled to both the signal transmitting path and the signal receiving path using an optical circulator, and the plurality of other single-mode fibers are coupled to the signal receiving path.