Diverged-Beam Optical Receiver Using Diffractive Demultiplexer
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Solution Overview
Problem
Current free-space optical communication systems are limited by the use of tightly-collimated beams, requiring precise alignment and high costs, with low-power and low-modulation-rate diverged pulses being used in niche applications, and have not effectively expanded beyond line-of-sight configurations.
Innovation Solution
The implementation of a diverged-beam free-space optical (DBFSO) communication system using multiple channels, where optical carrier signals of different wavelengths or polarizations are multiplexed and demultiplexed using diffraction gratings or other optics, enabling higher data rates up to 1 Tbps over a single optical link, with spatial separation and differential detection to improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tightly-collimated beams are used for FSO communication, then alignment precision is improved, but system complexity and cost increase
Solution Approach 1:
The patent divides the communication link into multiple independent wavelength channels, each carrying separate data streams. This segmentation allows each channel to operate with relaxed alignment requirements while collectively achieving high data rates, resolving the contradiction between alignment precision and system complexity
Solution Approach 2:
The patent transitions from spatial domain multiplexing (requiring precise alignment) to spectral domain multiplexing using multiple wavelengths. By moving to another dimension (wavelength/frequency), the system achieves multiple channels without the stringent alignment requirements of traditional collimated beam systems
2Productivity
If multiple wavelengths are multiplexed together, then bandwidth is improved, but spectral separation complexity increases
Solution Approach 1:
The patent replaces complex mechanical spectral separation systems with diffractive optical elements (DOEs) that achieve wavelength separation through diffraction physics. This substitution maintains high bandwidth capability while reducing mechanical complexity and improving reliability
Solution Approach 2:
The patent changes the physical state and properties of optical components, using diffractive structures with specific micro-geometries that provide wavelength-dependent diffraction angles. This parameter change enables compact spectral separation without complex mechanical systems
3Ease of manufacture
If diverged pulses of light are used, then system cost is reduced, but modulation rate decreases
Solution Approach 1:
The patent merges multiple low-power diverged wavelength channels into a single communication link. While each individual channel uses simple diverged pulses with relaxed requirements, the combined capacity of multiple channels achieves high aggregate data rates, resolving the contradiction between system cost and modulation rate
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
This approach increases bandwidth and data rates, reduces system costs, and allows for more flexible and efficient communication by enabling multiple channels to operate over a single physical path, improving signal quality and expanding beyond line-of-sight configurations.
Implementation Method 1
spatially separate the optical beam by wavelength into the plurality of optical carrier signals
Implementation Method 2
convert the plurality of optical carrier signals into a respective plurality of electrical signals
Data Source
AI summary
An optical receiver is provided for a diverged-beam, free space optical communications system. The optical receiver includes a demultiplexer and a detector array. The demultiplexer includes a diffractive optic configured to receive an optical beam propagating in free space. The optical beam includes a plurality of optical carrier signals of respective wavelengths for a plurality of communication channels, and the diffractive optic is configured to spatially separate the optical beam by wavelength into the plurality of optical carrier signals. The detector array includes a plurality of optical detectors configured to convert the plurality of optical carrier signals into a respective plurality of electrical signals for the plurality of communication channels. The plurality of optical detectors includes at least twice as many optical detectors as optical carrier signals in the plurality of optical carrier signals.