Tunable Filter Grating for OWC Angle Sensitivity
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Solution Overview
Problem
Optical wireless communication systems face challenges in efficiently receiving data streams from mobile devices due to angle sensitivity of wavelength filters, which affects signal reception as the geometry between the transmitter and receiver changes, leading to interference and reduced data capacity.
Innovation Solution
An optical wireless communication receiver apparatus with a wavelength-selective element that directs beams based on their wavelength, using diffractive or refractive elements like diffraction gratings, filters, or etalons, and a control element to adjust physical properties such as temperature or orientation, ensuring optimal beam alignment and interference reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wavelength filters are used to select specific wavelengths, then interference between different signals is reduced, but the filter becomes sensitive to the angle of incidence, causing signal reception to degrade as geometry changes
Solution Approach 1:
The patent changes the physical parameter of the wavelength-selective element by controlling its temperature. By varying the temperature, the refractive index and physical dimensions of the diffraction grating are modified, which adjusts the wavelength selection and directionality. This allows the system to compensate for angle-of-incidence changes and maintain reliable signal reception across different geometries while still filtering out interference.
Solution Approach 2:
The patent introduces dynamic control of the wavelength-selective element's properties through temperature adjustment. Instead of a static filter, the system dynamically adapts the filter's characteristics in response to changing geometric conditions, maintaining optimal performance across varying angles of incidence while continuing to reject interference signals.
2Productivity
If multiple filters and detectors are used to handle multiple wavelengths, then data capacity increases, but the device becomes bulky and complex
Solution Approach 1:
The patent makes a single wavelength-selective element perform multiple functions by dynamically adjusting its temperature. The same diffraction grating can select different wavelengths at different temperatures, replacing the need for multiple static filters and detectors. This multi-functional approach increases data capacity while reducing device complexity and size.
Solution Approach 2:
By changing the temperature parameter of the wavelength-selective element, the system can tune it to select different wavelengths sequentially. This single-element multi-wavelength capability achieves high data capacity without requiring multiple physical filter-detector assemblies, thereby reducing overall device complexity.
3Measurement precision
If the wavelength-selective element is made angle-sensitive, then wavelength selection precision improves, but signal reception reliability deteriorates when geometry changes
Solution Approach 1:
The patent implements a feedback control mechanism where the system monitors the received signal and adjusts the temperature of the wavelength-selective element accordingly. This feedback loop compensates for angle-of-incidence variations, maintaining both precise wavelength selection and reliable signal reception even when the geometry between transmitter and receiver changes.
Solution Approach 2:
The system dynamically changes the temperature parameter of the wavelength-selective element to compensate for geometric changes. By adjusting the temperature in response to angle variations, the system maintains precise wavelength selection while preserving signal reception reliability across different operating conditions.
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 data reception by compensating for movement and geometry changes, maximizing signal-to-noise ratio and data stream quality, and allows for flexible selection of wavelengths, thereby improving the efficiency and reliability of optical wireless communication systems.
Implementation Method 1
the wavelength-selective element is wavelength-sensitive such as to direct the selected at least one of the beams in a first direction relative to its direction of receipt based on its wavelength
Implementation Method 2
diffractive or refractive elements like diffraction gratings, filters, or etalons
Implementation Method 3
a control element to adjust physical properties such as temperature or orientation
Implementation Method 4
controlling at least one physical property of the wavelength-selective element thereby to select said at least one of the beams
Data Source
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AI summary
An optical wireless communication (OWC) receiver apparatus for receiving data streams from at least one transmitter apparatus, each data stream encoded on a beam of light of a respective different wavelength or range of wavelengths propagating through free space between the at least one transmitter apparatus and the receiver apparatus, the apparatus comprising: a wavelength-selective element configured to receive the beams after their propagation through free space and to direct a selected at least one of the beams having a selected wavelength or range of wavelengths to a detector, wherein the detector is configured to receive said selected at least one of the beams and in response to output a detection signal; at least one control element operable to control at least one physical property of the wavelength-selective element thereby to select said at least one of the beams for direction to the detector.