Impact of Different Metals on the Performance of Slab Tamm Plasmon Resonators

Abstract

We investigate the concept of slab Tamm plasmons (STP) in regard to their properties as resonant absorber or emitter structures in the mid-infrared spectral region. In particular, we compare the selective absorption characteristics resulting from different choices of absorbing material, namely Ag, W, Mo or highly doped Si. We devised a simplified optimization procedure using finite element simulations for the calculation of the absorption together with the application of micro-genetic algorithm (GA) optimization. As characteristic for plasmonic structures, the specific choice of the metallic absorber material strongly determines the achievable quality factor (Q). We show that STP absorbers are able to mitigate the degradation of Q for less reflective metals or even non-metals such as doped silicon as plasmonic absorber material. Moreover, our results strongly indicate that the maximum achievable plasmon-enhanced absorption does not depend on the choice of the plasmonic material presuming an optimized configuration is obtained via the GA process. As a result, absorptances in the order of 50–80% could be achieved for any absorber material depending on the slab thickness (up to 1.1 µm) and a target resonance wavelength of 4.26 µm (CO2 absorption line). The proposed structures are compatible with modern semiconductor mass fabrication processes. At the same time, the optimization procedure allows us to choose the best plasmonic material for the corresponding application of the STP structure. Therefore, we believe that our results represent crucial advances towards corresponding integrated resonant absorber and thermal emitter components.

Design of a Slab Tamm Plasmon Resonator Coupled to a Multistrip Array Waveguide for the Mid Infrared

“…In the case of an application of the WAS concept in context with refractive index sensing, the quality factor Q = λ r /∆λ source FWHM plays a more dominant role [23]. As shown in our previous works, the thickness of the Si slab h correlates strongly with the level of light confinement for STP resonators [7,8] and, subsequently, the peak emittance (λ r ) as well as Q. By Equation ( 2), p is strongly impacted by h as well.…”

“…As for STP structures, we use the effective index of the corresponding fundamental slab waveguide mode (TE) instead. In analogy to the heuristic approach in [8], we design the Si regions of the resonator as d Si 2 = λ r /4n eff + δ skin n eff and d Si 4 = 3λ r /4n eff + δ skin n W (see Figure 1a), where n eff is the effective refractive index of the fundamental TE slab waveguide mode, δ skin = 2πκ W /λ r is the penetration depth of the field into tungsten and n W + iκ W is the complex refractive index of tungsten at λ r . The air regions d Air 1 and d Air 3 are both dimensioned as λ r /8, such that the optical path length of both gaps corresponds to a single quarter-wavelength layer.…”

“…One of the many approaches are Tamm plasmon-polariton (TP) absorbers and emitters [2][3][4][5][6]. We recently proposed the concept of a slab Tamm plasmon (STP) absorber, which features inherent coupling to (and from) the fundamental mode of a slab waveguide [7,8]. Such a structure constitutes a complete integrated waveguide-absorber system (WAS), which has high potential for various waveguide sensing applications.…”

Tamm plasmon polariton in planar structures: A brief overview and applications

“…The existence and Q-factor of the Tamm resonance modes depends upon the type of plasmon active metallic layer, thickness of the metallic layer and angle of incidence of light. Several studies on the effect of different metals on the Tamm plasmon modes [57][58][59] have been reported. To understand the effect of different plasmon active metals on the sensitivity of TPP resonance, a TP structure made of metal/SiO2/DBR has been designed and numerically investigated using TMM.…”

Design of a High Q-Factor Label-Free Optical Biosensor Based on a Photonic Crystal Coupled Cavity Waveguide

“…Among the different fields of biosensing, optical sensors are powerful candidates to tackle most of the mentioned challenges. Optical sensors convert light into an electrical signal for a real-time analysis of a (preferably) small volume of analyte [ 6 , 7 , 8 ]. There is a wide variety of different optical sensor technologies, such as waveguiding devices, surface functionalization, and optofluidic integration.…”