Chapter 5 Light-Emitting-Diode Device Design

Saul, R. H.; Lee, Tien Pei; Burrus, C.A.

doi:10.1016/s0080-8784(08)63044-6

Cited by 11 publications

(4 citation statements)

References 82 publications

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“…LEDs can have vastly different characteristics with regard to, for example, the frequency response (i.e., switching speed), luminous, colour rendering and efficiency. As for the LED's frequency response, it is well known that its frequency response follows the first order system [2]- [5], whereby its modulation bandwidth is mainly limited by the effective carrier lifetime which is typically 2-5 ns for InGaAsP LEDs [6] with a corresponding bandwidth up to hundreds of MHz.…”

Section: Introductionmentioning

confidence: 99%

Equivalent Circuit Model of High Power LEDs for VLC Systems

Ghassemlooy

Zvánovec

et al. 2019

2019 2nd West Asian Colloquium on Optical Wireless Communications (WACOWC)

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The equivalent circuit model for two commercial high power LEDs for illuminance is proposed and extensive measurements have been carried out to verify the accuracy of the model. In addition, the frequency response of two LEDs in the optical domain can be estimated using the transfer function of electrical equivalent circuit. It is shown that, the electrical parasitics in the chip and packaging introduce significant attenuation beyond a resonance frequcency. Care should be taken when designing high-speed driver and/or equalization circuits for VLC systems.

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Section: Introductionmentioning

confidence: 99%

Equivalent Circuit Model of High Power LEDs for VLC Systems

Ghassemlooy

Zvánovec

et al. 2019

2019 2nd West Asian Colloquium on Optical Wireless Communications (WACOWC)

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“…where denotes time-domain convolution, h LED (t ) is the LED's impulse response and its Laplace transform is given by [25]…”

Section: System Modelingmentioning

confidence: 99%

Should Analogue Pre-Equalisers be Avoided in VLC Systems?

Ghassemlooy

Zvánovec

et al. 2020

IEEE Photonics J.

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Visible light communication (VLC) systems are highly constrained by the limited 3-dB bandwidth of light-emitting diodes (LEDs). Analogue pre-equalisers have been proposed to extend the LED's bandwidth at the cost of reduced signal-to-noise ratio (SNR). Compared with the pre-equaliser, the multi-carrier modulation with bit-loading can efficiently use the spectrum beyond the LED's raw 3-dB bandwidth without incuring SNR penalties by employing multiple narrow quasi-flat sub-bands to eliminate the need for equalisation. In this work we show by means of theoretical and experimental investigation that VLC with multi-band carrierless amplitude and phase modulation with bit-loading can outperform VLC with analogue pre-equalisers.

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“…Optical fibre systems using light-emitting diode sources can provide reliable, inexpensive alternatives to laser-based systems (Saul et al, 1985). Because of the extremely long operating lifetimes of LEDs, even in hostile environments, LED-based systems can prove to be attractive alternatives to laser-based systems for many applications such is SL.…”

Section: Mpc Working Principlementioning

confidence: 99%

Multiple LED photographic curing of models for design verification

Niino¹,

Nakagawa

1999

Rapid Prototyping Journal

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At The Institute of Physical and Chemical Research (RIKEN) a new process named multiple LED photographic curing (MPC) has been developed. As a matter of priority, MPC is thought to be applied to concept modelling. The building data are available in bitmap or voxel representation respectively. In MPC, light is generated by light‐emitting diodes (LEDs). Exposing of a photopolymer happens through raster scanning. An array of multiple beams of light is projected onto the resin surface while the scan head moves across the vat. The fabrication of test parts has proven the system’s practical ability to create geometric objects. Surface finish is quite good, certainly adequate for most concept verification. Some obstacles such as low exposure energy have yet to be overcome. Scaling up the build envelope enables fabricating much larger parts.

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Chapter 5 Light-Emitting-Diode Device Design

Cited by 11 publications

References 82 publications

Equivalent Circuit Model of High Power LEDs for VLC Systems

Equivalent Circuit Model of High Power LEDs for VLC Systems

Should Analogue Pre-Equalisers be Avoided in VLC Systems?

Multiple LED photographic curing of models for design verification

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