Observing and controlling a Tamm plasmon at the interface with a metasurface

Abstract

We demonstrate experimentally that Tamm plasmons in the near-IR can be supported by a dielectric mirror interfaced with a metasurface, a discontinuous thin metal film periodically patterned on the sub-wavelength scale. More crucially, not only do Tamm plasmons survive the nano-patterning of the metal film, but they also become sensitive to external perturbations, as a result. In particular, by depositing a nematic liquid crystal on the outer side of the metasurface we were able to red-shift the spectral position of Tamm plasmon by 35 nm, while electrical switching of the liquid crystal enabled us to tune the wavelength of this notoriously inert excitation within a 10 nm range.A Tamm plasmon (TP) is a localized resonant optical state, a quasi-particle, which exists at the interface between a metal and a dielectric (or semiconductor) Bragg mirror. It was theoretically predicted in [1] and experimentally observed in [2]. The TP dispersion lies completely within the light cone and therefore, in contrast to an ordinary surface plasmon polariton, a Tamm plasmon can be excited with both TE and TM polarized light at any angle of incidence [1]. Another advantage of a Tamm plasmon over a surface plasmon polariton is that the former appears to be almost insensitive to dissipative losses in the metal film since its electromagnetic fields are localized predominantly in the non-absorbing Bragg mirror [3]. Because of its robust nature, a Tamm plasmon has been regarded as a viable alternative to conventional surface plasmons in a wide range of applications, including refractive index sensing, optical switches, semiconductor lasers, and temperature sensors [4,5,6,7,8,9,10]. For many practical applications it is important to realize an external dynamic control over the TP wavelength. Such a task, however, presents a formidable challenge given that the fields of a Tamm plasmon reside inside the Bragg mirror and, therefore, are very difficult to access from the outside. Correspondingly, most of the approaches proposed so far involved the integration of a control element into the very structure of the Bragg mirror [4,6,11,12,13,14], which may not always appear feasible. It has also been shown that the wavelength of a Tamm plasmon could change (although irreversibly) as a result of the lateral confinement of its fields achieved by patterning the metal film on the microscale [3,15,16].In this Letter we report on the first experimental observation of a near-IR Tamm plasmon at the interface between a Bragg mirror and a nano-patterned metal film acting as a nondiffracting optical metasurface. We found that the discrete framework of the metasurface exposed Tamm plasmon to external perturbations, such as changes of the refractive index in an adjacent medium, which enabled us to dynamically control the wavelength of this weakly coupled optical state in a simple yet efficient way.

Photonic and Plasmonic Metasensors

“…Artistic representations of various types of practically implemented Tamm mode-resonant metastructures are depicted in Figure 9. [316][317][318][319][320][321] Focusing on the biosensing capabilities of the TPP metastructures, a revolutionary work from Fainstein's group demonstrates how robustly sustained Tamm states in mesoporous multilayers can be employed for sensing purposes. [322] The proposed multilayer system comprises porous SiO 2 and TiO 2 layers, as well as a permeable Bragg reflector and a flat gold film (Figure 10a).…”

“…Copyright 2016, American Chemical Society. b) Reproduced with permission [317]. Copyright 2020, De Gruyter.…”

Metal–Dielectric Polarization-Preserving Anisotropic Mirror for Chiral Optical Tamm State

“…The TPP manifests itself in experiments as a resonance in the optical spectra of a sample [5,6]. The interest in localized states of this type stems from their potential for use in various optical devices, including sensors [7][8][9], detectors [10][11][12], lasers [13][14][15], absorbers [16,17], filters [18][19][20], and solar cells [21,22].…”

Influence of Rugate Filters on the Spectral Manifestation of Tamm Plasmon Polaritons

“…TPPs manifest themselves optically in the form of narrow dips/peaks in the reflection/transmission spectra in the spectral region corresponding to the photonic band gap of the Bragg mirror. TPPs are a good alternative to conventional surface plasmons, with potential applications for sensors [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ], Tamm plasmon-based lasers [ 15 , 16 , 17 ], optical switches and filters [ 18 , 19 , 20 ], liquid crystal-tuned Tamm plasmon devices [ 21 , 22 , 23 ], and selective thermal and light emitters [ 24 , 25 , 26 , 27 , 28 ].…”