Design and Fabrication of Optical Bandpass Filters for Safe 222 nm UVC Light Generation in Medical Disinfection Applications

Document Type : Original Paper

Authors

1 Department of Physics, Faculty of Sciences, Ferdowsi University, Mashhad, Iran

2 Department of Physics, Amirkabir University of Technology, Tehran, Iran

3 Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

10.22038/ijmp.2026.94368.2677

Abstract

Introduction: Recent global pandemics have highlighted the urgent need for effective and safe sterilization technologies. Ultraviolet-C (UVC) radiation at a wavelength of 222 nm has attracted considerable attention due to its strong germicidal efficacy combined with its limited penetration into human tissues. The generation of safe 222 nm UVC light requires optical bandpass filters that selectively transmit this wavelength while suppressing longer, potentially harmful emissions.
Material and Methods: In this study, metal–dielectric optical bandpass filters optimized for 222 nm UVC applications were designed and fabricated. The design process involved a review of previous studies, material selection, and layer thickness optimization using numerical modeling based on the transfer matrix method. Aluminum was employed as the metallic layer and magnesium fluoride as the dielectric material. The filters were fabricated using physical vapor deposition and characterized by UV–Vis spectroscopy. The effects of deposition errors, post-deposition thermal annealing, and laser damage threshold were also investigated.
Results: Several optimized designs for 222 nm optical bandpass filters were obtained, offering flexibility based on material availability and desired spectral characteristics. Experimental results demonstrated peak transmission wavelengths close to 222 nm with acceptable bandwidths for safe UVC applications. Thickness variations in dielectric layers were identified as the dominant factor influencing spectral shifts, while post-deposition thermal annealing was found to degrade filter performance. The laser damage threshold of the fabricated filters was measured to be approximately 1.3 J/cm².
Conclusion: The developed metal–dielectric bandpass filters demonstrate suitable optical performance for generating safe 222 nm UVC radiation. These findings support the development of reliable far-UVC light sources for medical disinfection applications, contributing to safer sterilization technologies in healthcare and public environments.

Keywords

Main Subjects

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Iranian Journal of Medical Physics
Volume 23, Issue 1
January and February 2026
Pages 46-58

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History

  • Receive Date: 03 February 2026
  • Revise Date: 15 February 2026
  • Accept Date: 18 March 2026

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