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A high-birefringence photonic crystal fiber polarization filter is proposed. The coupling theory is used to explain full and incomplete couplings. The resonance point can be adjusted to the communication band by optimizing the fiber structure parameters. Numerical simulation results indicate that the resonance strength can reach 924.96 and <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mn>710.28</mn>
<mtext> </mtext>
<mi>dB</mi>
<mo>.</mo>
<msup>
<mi>cm</mi>
<mrow>
<mo>−</mo>
<mn>1</mn>
</mrow>
</msup>
</mrow>
</math>
</inline-formula> at the communication wavelength of 1.31 and <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mn>1.55</mn>
<mtext> </mtext>
<mi>μ</mi>
<mi mathvariant="normal">m</mi>
</mrow>
</math>
</inline-formula> in <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mi>x</mi>
</mrow>
</math>
</inline-formula>- and <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mi>y</mi>
</mrow>
</math>
</inline-formula>-polarized directions, respectively. By filling liquid analyte, the confinement loss can reach <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mn>804.52</mn>
<mtext> </mtext>
<mi>dB</mi>
<mo>.</mo>
<msup>
<mi>cm</mi>
<mrow>
<mo>−</mo>
<mn>1</mn>
</mrow>
</msup>
</mrow>
</math>
</inline-formula> at the wavelength of <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mn>1.55</mn>
<mtext> </mtext>
<mi>μ</mi>
<mi mathvariant="normal">m</mi>
</mrow>
</math>
</inline-formula>. Furthermore, when the fiber length of <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mi>L</mi>
</mrow>
</math>
</inline-formula> equals <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mn>500</mn>
<mtext> </mtext>
<mi>μ</mi>
<mi mathvariant="normal">m</mi>
</mrow>
</math>
</inline-formula>, the peak value of the cross talk (CT) can reach 389.15 and <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mo form="prefix">−</mo>
<mn>280.52</mn>
<mtext> </mtext>
<mi>dB</mi>
</mrow>
</math>
</inline-formula>, respectively. When the length of the fiber <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mi>L</mi>
</mrow>
</math>
</inline-formula> equals <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mrow>
<mn>200</mn>
<mtext> </mtext>
<mi>μ</mi>
<mi mathvariant="normal">m</mi>
</mrow>
</math>
</inline-formula>, the bandwidth of the CT better than 20 dB is up to 120 nm at the wavelength of 1.31 μm, and the bandwidth of the <inline-formula>
<math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML">
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