Gas sensing near exceptional points
Ping Nie, Lijuan Sheng, Linguo Xie, Zhihao Chen, Xinxing Zhou, Yu Chen, Xiao Lin
Abstract
Abstract Here we investigate the possibility of gas sensing with ultrahigh sensitivity by exploiting the exceptional point (EP) in a non-Hermitian system. The underlying mechanism is that the transverse displacement induced by the photonic spin Hall effect (PSHE), which is significantly enhanced near EPs, is ultra-sensitive to the variation of refractive index in gas media. With the application of the weak measurement technique, we find that the sensitivity of the gas sensing can reach <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> <mml:mrow> <mml:mtext>RIU </mml:mtext> </mml:mrow> <mml:mi>μ</mml:mi> <mml:mrow> <mml:msup> <mml:mrow> <mml:mtext>m</mml:mtext> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . Moreover, if we further reduce the in-plane wavevector component of probe Gaussian light, the sensitivity can be readily improved, up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>8</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> <mml:mrow> <mml:mtext>RIU </mml:mtext> </mml:mrow> <mml:mi>μ</mml:mi> <mml:mrow> <mml:msup> <mml:mrow> <mml:mtext>m</mml:mtext> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> , which is much better than that of previous PSHE-based gas sensors operating away from the EP. Therefore, our proposed scheme may be favorable for the development of high-performance sensors.