Double-Resolved Beam Steering by Metagrating-Based Tamm Plasmon Polariton.

We consider Tamm plasmon polariton in a subwavelength grating patterned on top of a Bragg reflector. We demonstrate dynamic control of the phase and amplitude of a plane wave reflected from such metagrating due to resonant coupling with the Tamm plasmon polariton. The tunability of the phase and amplitude of the reflected wave arises from modulation of the refractive index of a transparent conductive oxide layer by applying the bias voltage. The electrical switching of diffracted beams of the ±1st order is shown. The possibility of doubling the angular resolution of beam steering by using asymmetric reflected phase distribution with integer and half-integer periods of the metagrating is demonstrated.

Application of Tamm Plasmon Polaritons and Cavity Modes for Biosensing in the Combined Spectroscopic Ellipsometry and Quartz Crystal Microbalance Method.

Low-cost 1D plasmonic photonic structures supporting Tamm plasmon polaritons and cavity modes were employed for optical signal enhancement, modifying the commercially available quartz crystal microbalance with dissipation (QCM-D) sensor chip in a combinatorial spectroscopic ellipsometry and quartz microbalance method. The Tamm plasmon optical state and cavity mode (CM) for the modified mQCM-D sample obtained sensitivity of ellipsometric parameters to RIU of ΨTPP = 126.78 RIU-1 and ΔTPP = 325 RIU-1, and ΨCM = 264 RIU-1 and ΔCM = 645 RIU-1, respectively. This study shows that Tamm plasmon and cavity modes exhibit about 23 and 49 times better performance of ellipsometric parameters, respectively, for refractive index sensing than standard spectroscopic ellipsometry on a QCM-D sensor chip. It should be noted that for the optical biosensing signal readout, the sensitivity of Tamm plasmon polaritons and cavity modes are comparable with and higher than the standard QCM-D sensor chip. The different origin of Tamm plasmon polaritons (TPP) and cavity mode (CM) provides further advances and can determine whether the surface (TPP) or bulk process (CM) is dominating. The dispersion relation feature of TPP, namely the direct excitation without an additional coupler, allows the possibility to enhance the optical signal on the sensing surface. To the best of our knowledge, this is the first study and application of the TPP and CM in the combinatorial SE-QCM-D method for the enhanced readout of ellipsometric parameters.

Tunable Narrowband Silicon-Based Thermal Emitter with Excellent High-Temperature Stability Fabricated by Lithography-Free Methods.

Thermal emitters with properties of wavelength-selective and narrowband have been highly sought after for a variety of potential applications due to their high energy efficiency in the mid-infrared spectral range. In this study, we theoretically and experimentally demonstrate the tunable narrowband thermal emitter based on fully planar Si-W-SiN/SiNO multilayer, which is realized by the excitation of Tamm plasmon polaritons between a W layer and a SiN/SiNO-distributed Bragg reflector. In conjunction with electromagnetic simulations by the FDTD method, the optimum structure design of the emitter is implemented by 2.5 periods of DBR structure, and the corresponding emitter exhibits the nearly perfect narrowband absorption performance at the resonance wavelength and suppressed absorption performance in long wave range. Additionally, the narrowband absorption peak is insensitive to polarization mode and has a considerable angular tolerance of incident light. Furthermore, the actual high-quality Si-W-SiN/SiNO emitters are fabricated through lithography-free methods including magnetron sputtering and PECVD technology. The experimental absorption spectra of optimized emitters are found to be in good agreement with the simulated absorption spectra, showing the tunable narrowband absorption with all peak values of over 95%. Remarkably, the fabricated Si-W-SiN/SiNO emitter presents excellent high-temperature stability for several heating/cooling cycles confirmed up to 1200 K in Ar ambient. This easy-to-fabricate and tunable narrowband refractory emitter paves the way for practical designs in various photonic and thermal applications, such as thermophotovoltaic and IR radiative heaters.

Chiral-Selective Tamm Plasmon Polaritons.

Chiral-selective Tamm plasmon polariton (TPP) has been investigated at the interface between a cholesteric liquid crystal and a metasurface. Different from conventional TPP that occurs with distributed Bragg reflectors and metals, the chiral-achiral TPP is successfully demonstrated. The design of the metasurface as a reflective half-wave plate provides phase and polarization matching. Accordingly, a strong localized electric field and sharp resonance are observed and proven to be widely tunable.