Spectral spatial coherence of high-power multi-chip LEDs

Chen, Guangming; Tao, Hua; Lin, Hungyen; Chen, Ziyang; Pu, Jixiong

doi:10.1007/s11801-012-2322-6

Cited by 1 publication

(2 citation statements)

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“…After reviewing the literature [6][7][8], it is evident that the spatial coherence length, σ, of LED emitting chips typically falls within the micrometer range. It is important to take into account the size of the LED light source following processing and optical packaging, as the spatial coherence length of the emitted light on the exit plane generally ranges from several to tens of micrometers.…”

Section: Led-gsm Modelmentioning

confidence: 99%

“…In the past decades, the coherence of light fields has been studied in the context of LED applications such as optical communication [1,2], digital holographic displays [3], and interferometric measurements [4,5]. Measurements of the spatial coherence of LED light fields indicate that they are not completely incoherent, but instead, contain partially coherent light with spatial coherence lengths varying from a few to several tens of micrometers [6,7]. The size of the spatial coherence length is linked to the LED light source material and the structure of the emitting chip [8].…”

Section: Introductionmentioning

confidence: 99%

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Light field analysis for modeling and transmission characteristics of partially coherent light-emitting diodes

Zhang

Liu

et al. 2023

Front. Phys.

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When analyzing the transmission characteristics of LEDs for long-distance lighting and communication applications, the light field is commonly assumed to be fully incoherent. However, in reality, the LED light source emits partially coherent light with a spatial coherence length on the order of microns. This paper is based on the generalized higher-order Lambert model of LEDs and aims to construct a Gaussian-Schell model for the LED beam (LED-GSM) on the near-field source plane, with a half-power angle of no more than 10o. Utilizing the cross-spectral density function transmission theory for partially coherent light, this paper provides the LED-GSM model’s spatial coherence length and beam radius at different distances and designs an experiment for measuring the spatial coherence length of LED beams. Experimental measurements of the spatial coherence length and beam spot size of LED beams at different distances are carried out using a Thorlabs LED528EHP light source. The experimental results match well with the theoretical simulations of the LED-GSM model, thus validating its effectiveness. Then, the proposed LED-GSM model is utilized to investigate the long-distance transmission characteristics of partially coherent narrow-beam LED light. Simulation results indicate that the spatial coherence length of the LED light field can reach tens to hundreds of millimeters over transmission distances of several kilometers. The beam radius is much smaller than that of the beam radius based on the fully incoherent model, and the beam intensity distribution also displays distinct differences.

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Section: Led-gsm Modelmentioning

confidence: 99%