Ultrathin metal-dielectric planar interface for high-performance photonic spin Hall effect

Abstract This study explores the photonic spin Hall effect (PSHE) with a focus on its sensitivity to incident wave polarization and physical parameter variations. Traditionally, surface plasmonic resonance (SPR) systems mainly enhance H-polarized PSHE. However, our proposed method involves an ultrathin metal layer, capped with a glass dielectric layer on a glass substrate, to achieve high-performance PSHE for both H- and V-polarization waves. This high-performance PSHE in terms of enhancement in PSHE magnitudes arises from the simultaneous presence of SPR and waveguiding effects, resulting in the emergence of hybrid transverse electric and transverse magnetic modes. Investigating Au and Ag ultrathin metal layers, we find that the highest H-polarized PSHE occurs at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mstyle scriptlevel="0"/> <mml:mn>1.52</mml:mn> <mml:mo>×</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>6</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> nm and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mstyle scriptlevel="0"/> <mml:mn>2.05</mml:mn> <mml:mo>×</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>5</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> nm for Au and Ag, respectively. Similarly, for V-polarized incident light, maximum enhanced PSHE is observed at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mstyle scriptlevel="0"/> <mml:mn>1.58</mml:mn> <mml:mo>×</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>5</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> nm and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mstyle scriptlevel="0"/> <mml:mn>9.48</mml:mn> <mml:mo>×</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>4</mml:mn> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> nm for Au and Ag, respectively. By adjusting the thickness of the metal and/or glass cap layer, precise control over PSHE amplitude and active polarization response is achievable. This research unveils unique capabilities for generating hybrid modes that enhance PSHE for both polarizations, offering a potential platform for developing tunable polarization-favorable spin optics optoelectronic devices.