<p>In this work, a dual-window polarization filter has been designed using photonic crystal fiber (PCF) having pentagonal arrangements of circular air holes. Only two holes in the cladding are coated with silver (Ag) instead of gold for plasmon excitation and these two Ag-coated holes are filled with indium tin oxide (ITO), which is an epsilon-near-zero (ENZ) material to prevent the oxidization of silver. Fused silica is chosen as background material. The bandwidth and also the crosstalk are calculated to obtain an optimized filter at communication wavelengths that passes only X-polarized mode and blocks Y-polarized mode. The confinement losses at the wavelengths of 1.31 <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11082_2025_8419_Article_IEq1.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="26" /> </InlineMediaObject> <EquationSource Format="TEX">$\mu \text {m}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mtext>m</mtext> </mrow> </math></EquationSource> </InlineEquation> and 1.55 <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11082_2025_8419_Article_IEq1.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="26" /> </InlineMediaObject> <EquationSource Format="TEX">$\mu \text {m}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mtext>m</mtext> </mrow> </math></EquationSource> </InlineEquation> are 1021.8 dB/cm and 867.03 dB/cm, respectively. The filter performs as a wideband filter with a bandwidth of 735 nm when the length is only 60 <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11082_2025_8419_Article_IEq1.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="26" /> </InlineMediaObject> <EquationSource Format="TEX">$\mu \text {m}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mtext>m</mtext> </mrow> </math></EquationSource> </InlineEquation>. The potential use of the filter could be in optical communication and sensing.</p>

Design of a short length wideband polarization filter using PCF having Ag coated holes filled with ENZ materials

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发表日期：

2025年8月26日

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Shahriar Ahmed,
Md. Hasibul Hasan,
Shah Laheen Mashahad,
Hasan Masud Khan,
M. Shah Alam

摘要

In this work, a dual-window polarization filter has been designed using photonic crystal fiber (PCF) having pentagonal arrangements of circular air holes. Only two holes in the cladding are coated with silver (Ag) instead of gold for plasmon excitation and these two Ag-coated holes are filled with indium tin oxide (ITO), which is an epsilon-near-zero (ENZ) material to prevent the oxidization of silver. Fused silica is chosen as background material. The bandwidth and also the crosstalk are calculated to obtain an optimized filter at communication wavelengths that passes only X-polarized mode and blocks Y-polarized mode. The confinement losses at the wavelengths of 1.31 $\mu \text {m}$ $μ m$ and 1.55 $\mu \text {m}$ $μ m$ are 1021.8 dB/cm and 867.03 dB/cm, respectively. The filter performs as a wideband filter with a bandwidth of 735 nm when the length is only 60 $\mu \text {m}$ $μ m$ . The potential use of the filter could be in optical communication and sensing.