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One‐Dimensional Photonic Crystal for Surface Mode Polarization Control

2022; Wiley; Volume: 10; Issue: 21 Linguagem: Inglês

10.1002/adom.202200759

2195-1071

Erika Mogni, Giovanni Pellegrini, Jorge Gil‐Rostra, F. Yubero, Giuseppina Simone, Stefan Fossati, Jakub Dostálek, Rebeca Martínez Vázquez, Roberto Osellame, Michele Celebrano, Marco Finazzi, Paolo Biagioni,

Plasmonic and Surface Plasmon Research

Abstract Bloch surface waves sustained by truncated 1D photonic crystals (1DPCs) are well known tools for surface‐enhanced spectroscopy. They provide strongly confined fields with uniform distribution over a large surface area, a characteristic exploited in standard refractometric sensing. However, their application to polarization‐sensitive investigations is not straightforward because the transverse electric (TE) and magnetic (TM) surface modes possess distinct dispersion relations, therefore their relative phase is not conserved along propagation and the polarization state of any wave obtained by combining these modes is ill‐defined. In this work, a novel design of a 1DPC is realized in which the TE and TM modes exhibit the same phase velocity over a broadband spectral range and thus their dispersion relations overlap. The capability to simultaneously excite TE and TM modes with a well‐defined phase relation allows the generation of surface waves with a controlled polarization state. This paves the way to polarization‐resolved surface‐enhanced analysis, including, for example, linear and circular dichroism spectroscopy of grafted molecular layers at the photonic crystal surface.