Output Power Monitoring of Ultraviolet Light-Emitting Diode via Sapphire Substrate

Ching-Hua Chen; Jia-Jun Zhang; Chang-Han Wang; Tzu-Chieh Chou; Rui-Xiang Chan; Pinghui S. Yeh

doi:10.3390/photonics7030063

Photonics (Aug 2020)

Output Power Monitoring of Ultraviolet Light-Emitting Diode via Sapphire Substrate

Ching-Hua Chen,
Jia-Jun Zhang,
Chang-Han Wang,
Tzu-Chieh Chou,
Rui-Xiang Chan,
Pinghui S. Yeh

Affiliations

Ching-Hua Chen: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
Jia-Jun Zhang: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
Chang-Han Wang: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
Tzu-Chieh Chou: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
Rui-Xiang Chan: Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
Pinghui S. Yeh: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

DOI: https://doi.org/10.3390/photonics7030063
Journal volume & issue: Vol. 7, no. 3
p. 63

Abstract

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Ultraviolet (UV) light plays an important role in air/water/surface sterilization now. Maintaining a certain light intensity is often required to attain the targeted effect. In this paper, on-chip power monitoring of a UV-A light-emitting diode (LED) via sapphire substrate is reported. A p–i–n photodiode loop that surrounds the UV-A LED was designed and fabricated to monitor the output power by detecting the scattered light of the LED propagating through the sapphire substrate. No particular waveguide structure or processing parameter control was needed. The monitoring responsivities per unit of surface-emitting power obtained were approximately 21 and 25 mA/W at photodiode biases of 0 and 3 V, respectively. When combined with a transimpedance amplifier, a monitoring responsivity of 1.87 V/mW at zero bias was measured, and a different monitoring responsivity could be customized by adjusting the gain of the transimpedance amplifier. The operation principle of this device might be applicable to UV-B or UV-C LEDs.

Published in Photonics

ISSN: 2304-6732 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Engineering (General). Civil engineering (General): Applied optics. Photonics
Website: http://www.mdpi.com/journal/photonics

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