Tunable wide bandstop and narrow bandpass filters based on one-dimensional ternary photonic crystals comprising defects of silver nanoparticles in water

• Published in: The Journal of physics and chemistry of solids Vol. 161; p. 110484
• Main Authors: Abohassan, Khedr M., Ashour, Hassan S., Abadla, Mazen M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-02-2022
• Subjects: Dielectric constant; Optical filter; Photonic crystal; Silver nanoparticles; Dielectric constant; Optical filter; Photonic crystal; Silver nanoparticles
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2021.110484

In this study, we propose a novel structure comprising a one-dimensional photonic crystal of ZnSe/Nb2O5/BK7 as a tunable wide bandstop filter to cover the visible range of 500–800 nm. The transmittance spectrum of the structure was numerically investigated using the transfer matrix method. A stopband covering the range of 609–682 nm was obtained when the structure had nine ternary unit cells. The range widened to cover 576–707 nm when the number of unit cells increased to 20. A narrow bandpass filter was obtained when a defective layer comprising silver nanoparticles dispersed in water was inserted in the middle of the photonic crystal. We demonstrated the tuning of the single bandpass channel by considering the dispersion of the materials due to the modulation of the filling factor and size of the silver nanoparticles as well as the angle of incidence for radiation. The resonant peak with a transmittance of more than 0.85 obtained at normal incidence shifted from 620.8 to 644.5 nm within the bandgap as the filling factor increased from 0.0 to 0.10. We also found that the resonant peak shifted slightly (from 631.5 to 632.4 nm) when the radius of the silver nanoparticles increased from 1.0 to 15.0 nm. In addition, when the angle of incidence increased from 10° to 80°, the resonant peak shifted from 630.0 to 545.8 nm. Therefore, the proposed structure is promising for fabricating practical tunable wide bandstop and single-channel bandpass filters in the visible region.
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•Stopband width dependent on the number of unit cells up to 20 cells.•Resonant wavelength of bandpass channel linearly dependent on volume concentration of the silver nanoparticles.•Resonant wavelength of the bandpass channel not significantly dependent on radius of the silver nanoparticles.•Resonant wavelength of the bandpass channel inversely proportional to radiation's angle of incidence.•Proposed structures promising tunable wide bandstop and narrow single-channel bandpass filters in the visible region.