Visible-Light Optical Transceiver With Multicore Fibre Dispersion Control
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Solution Overview
Problem
Conventional fibre-optic communication systems are costly due to the need for precise alignment of optical fibres and expensive components like single-mode and multi-mode lasers and silicon-germanium receivers, and face issues with chromatic dispersion and high-speed transmission limitations.
Innovation Solution
An optical transmitter unit with an array of micro-LEDs and a controller using analogue circuitry for encoding data, coupled with an optical filter to reduce chromatic dispersion, and a photodetector array with CMOS sensors to decode data, all connected via a multicore fibre optic cable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fibre-optic communication systems use precise alignment of optical fibres with light sources and light detectors, then transmission reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the mechanical alignment system (precise physical alignment of optical fibres with light sources and detectors) with an optical coupling system using lens arrays. The lens array focuses light from each light source onto the corresponding photodetector, eliminating the need for mechanical precision in fibre alignment while maintaining reliable optical coupling.
Solution Approach 2:
The patent uses an array of light sources and an array of photodetectors where each element in the array corresponds to a specific spatial position. This array structure allows parallel transmission across multiple channels, effectively copying the transmission function across multiple independent paths, thereby reducing the stringency of alignment requirements for each individual channel.
2Reliability
If conventional systems use expensive light sources and receivers (single-mode and multi-mode lasers and silicon-germanium receivers), then transmission quality is improved, but device cost increases
Solution Approach 1:
The patent employs commodity micro-LEDs and CMOS photodetector arrays instead of expensive single-mode and multi-mode lasers plus silicon-germanium receivers. These cheaper components are sufficient for the application, eliminating the need for costly specialized components while maintaining acceptable transmission quality.
Solution Approach 2:
The patent changes the operating parameters by using visible light wavelengths (400-700nm) instead of infrared wavelengths typical of conventional optical communication. This parameter change enables the use of cheaper micro-LEDs and CMOS sensors, which are optimized for visible light detection, thereby reducing device cost while maintaining transmission capability.
3Productivity
If systems use complex coding schemes (PAM4 or OFDM) to maximise bandwidth per lane, then data transmission capacity is improved, but device complexity increases
Solution Approach 1:
Instead of using complex coding schemes on a single lane, the patent segments the transmission into multiple parallel lanes using a spatial array of light sources and photodetectors. Each lane can use simple on-off keying modulation, and the total bandwidth is achieved through parallel transmission across all lanes, avoiding complex digital signal processing.
Solution Approach 2:
The patent replaces complex digital coding schemes (PAM4, OFDM) with a simpler optical modulation approach using intensity modulation of light sources. The information is encoded in the intensity of light rather than through complex digital signal processing, thereby reducing device complexity while maintaining high throughput through spatial parallelism.
4Productivity
If systems transmit at higher speeds, then data transmission capacity is improved, but chromatic dispersion increases
Solution Approach 1:
The patent changes the wavelength parameter by using visible light (400-700nm) instead of infrared light. This parameter change reduces chromatic dispersion in the optical fibre, as visible light experiences lower dispersion than infrared light at typical transmission distances. This enables higher transmission speeds without severe dispersion penalties.
Solution Approach 2:
The patent introduces a lens array as an intermediary optical element that couples the light sources to the photodetectors. This intermediary system allows for precise optical alignment and focus, compensating for any chromatic dispersion effects and maintaining signal integrity at high transmission speeds.
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
Enables cost-effective, high-bandwidth data transmission with reduced chromatic dispersion by using commodity components and simpler digital signal processing, facilitating parallel data transmission across multiple channels.
Implementation Method 1
an array of light sources, each light source configured to transmit visible light along a respective core of the multicore fibre optic cable for receipt at a corresponding photodetector array of the optical receiver unit
Implementation Method 2
an optical filter configured to reduce chromatic dispersion
Implementation Method 3
The optical filter configured to reduce chromatic dispersion may comprise optical band-pass filter configured to narrow pulses of modulated light emitted by the light sources
Implementation Method 4
a photodetector array, each photodetector in the photodetector array configured to receive modulated visible light from an array of light sources of the optical transmitter unit via a respective core of the multicore fibre optic cable
Data Source
AI summary
An optical transmitter includes an array of light sources to transmit visible light having a wavelength of from 580 nm to 700 nm along a respective core of a multicore fibre optic cable for receipt at a corresponding photodetector array of an optical receiver unit, and a controller that receives data from a transmitting computer system and encodes and transmits it by modulating the visible light output by the array of light sources. An optical receiver unit includes a photodetector array to receive the modulated visible light from the multicore fibre optic cable; and a controller to receive the output of the photodetectors; decode data from the received output, and provide the decoded data to a receiving computer system. An optical transceiver unit includes the optical transmitter and optical receiver.