Structured gallium nitride LED light sources for visible light communications.
Lead Research Organisation:
University of Strathclyde
Department Name: Physics
Abstract
This project focuses on the development of novel structured light sources for LiFi and visible light communications (VLC) applications.
LED-based solid-state lighting offers exciting prospects for new forms of wireless communications infrastructure, to complement existing WiFi and provide additional deployment opportunities and functionality. The basic idea is that LED-based solid-state lighting, being based on semiconductor technology, can interface very effectively to advanced (CMOS) control electronics and can therefore operate in a sophisticated manner directly under electronic control, in effect facilitating the emergence of 'Digital' Lighting. In particular, a combination of direct data modulation of individual LEDs of micro-sized dimensions can be combined with the ability of arrays of these sources to create complex spatio-temporal illumination patterns, facilitating a combination of communications and indoor navigation functions and implementing spatial and spectral multiplexing.
We have, over the past few years under EPSRC support, established new benchmarks in the performance of electronically interfaced gallium nitride LEDs. We have shown that individual micro-pixel GaN LEDs can have modulation bandwidths in excess of 1Gb/s and, with appropriate advanced data encoding, transmit data rates at beyond 10Gb/s. These high data rates have been achieved with a change of geometry in the LED pixels, and we need to understand the physical mechanisms behind this effect, whilst also exploring further shape change and other effects to see if the data rate can be pushed any further. In addition, we have only begun to understand the implications of structured light patterning produced by arrays of our sources. Much further work needs to be done to explore new spatial and spectral data encoding methods and in combining them with the ability of structured lighting to locate and track objects. This studentship will explore all of these issues, in collaboration with external partner universities including Oxford, Cambridge, St Andrews and Edinburgh.
LED-based solid-state lighting offers exciting prospects for new forms of wireless communications infrastructure, to complement existing WiFi and provide additional deployment opportunities and functionality. The basic idea is that LED-based solid-state lighting, being based on semiconductor technology, can interface very effectively to advanced (CMOS) control electronics and can therefore operate in a sophisticated manner directly under electronic control, in effect facilitating the emergence of 'Digital' Lighting. In particular, a combination of direct data modulation of individual LEDs of micro-sized dimensions can be combined with the ability of arrays of these sources to create complex spatio-temporal illumination patterns, facilitating a combination of communications and indoor navigation functions and implementing spatial and spectral multiplexing.
We have, over the past few years under EPSRC support, established new benchmarks in the performance of electronically interfaced gallium nitride LEDs. We have shown that individual micro-pixel GaN LEDs can have modulation bandwidths in excess of 1Gb/s and, with appropriate advanced data encoding, transmit data rates at beyond 10Gb/s. These high data rates have been achieved with a change of geometry in the LED pixels, and we need to understand the physical mechanisms behind this effect, whilst also exploring further shape change and other effects to see if the data rate can be pushed any further. In addition, we have only begun to understand the implications of structured light patterning produced by arrays of our sources. Much further work needs to be done to explore new spatial and spectral data encoding methods and in combining them with the ability of structured lighting to locate and track objects. This studentship will explore all of these issues, in collaboration with external partner universities including Oxford, Cambridge, St Andrews and Edinburgh.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509760/1 | 01/10/2016 | 30/09/2021 | |||
| 1810331 | Studentship | EP/N509760/1 | 01/10/2016 | 31/03/2020 | Mark Stonehouse |
| Description | -A novel µLED array was designed and fabricated hosting a common p-type electrode and individually addressable n-type electrodes. This is a reverse structure when compared to typical µLED arrays and allows for a better integration with NMOS transistors, thus allowing for faster modulation speeds. The array features 24 µm diameter circular pixels and operates at 450 nm. It is capable of providing over 2 mW of optical power with a bandwidth of 440 MHz. The linearity of the device was tested using stepped saw-tooth waveforms whilst the data transmission was tested using on-off-keying and PAM modulation schemes. This was published with IEEE photonics. -A micro-scale maskless photo-lithography system was designed and developed using a custom made µLED array. The motivation behind this is to allow and introduce additional technology previously demonstrated with LED arrays such as tracking, object recognition and characterisation alongside traditional photo curing. The initial design and development of the system was presented and published at IEEE BICOP. This included a look into the limitations and trade-offs between high resolution, field of view and cure speeds. Notable findings since has been the implementation of feature tracking using reflective and fluorescent targets. -The maskless photolithography system was adapted to also feature a secondary uLED array with tessalated pixels to give a simultaneous feature recognition and automated alignment functionality. This LED array is capable of other structured illumination based functionality though only these have been implemented. This system is now capable of photocuring structures whilst self-aligning to randomly distributed, non-standard alignment markers. This work has been presented at IPC and UKS. |
| Exploitation Route | The photolithography setup can be further adapted to change the camera to a single pixel camera along with implementing additional strucured illumination based features such as surface relief metrology |
| Sectors | Digital/Communication/Information Technologies (including Software),Manufacturing, including Industrial Biotechology |