Deterministic inverse design of Tamm plasmon thermal emitters with multi-resonant control

Abstract

Wavelength-selective thermal emitters (WS-EMs) are of high interest due to the lack of cost-effective, narrow-band light sources in the mid-to long-wave infrared. Cost-effective WS-EMs can be realized via Tamm plasmon polariton (TPP) structures supported by distributed Bragg reflectors (DBRs) on metal layers, however, optimizing TPP-WS-EMs is challenging because of the large number of parameters to optimize.To address this challenge, we use stochastic gradient descent (SGD) to optimize TPP-WS-EMs composed of an aperiodic DBR deposited on doped cadmium oxide (CdO) plasmonic films. While the SGD-optimized, aperiodic DBR offers extensive spectral control, the material choice, i.e., plasma-frequency-tunable doped CdO, enables the design capabilities not accessible with noble metals. Here, the individual layer thickness and carrier density of CdO are optimized by our SGD inverse design strategy. The resultant experimental designs demonstrate TPP-WS-EMs exhibiting isolated, high-Q (narrow bandwidth), and structures featuring multiple emission bands for applications such as free-space communications and gas sensing. Furthermore, we illustrate the deterministic design capability within the infrared, such as user-designated Q-factors (28 -10,127) at a desired frequency, multi-band emitters with user-defined Q, and the ability to directly match arbitrary chemical absorption spectra. Thus, the combination of our SGD inverse design and the broadly tunable plasma frequency of CdO enables lithography-free, CMOS-compatible, and wafer-scale solutions for WS-EMs with unprecedented spectral control.

Anisotropy and Modal Hybridization in Infrared Nanophotonics Using Low-Symmetry Materials

“…Importantly, due to the unique low-loss nature of the topological transition, it was possible to visualize intermediate propagating states, which permits the unveiling of the topological origin of the transition. The general and fundamental characters of these findings extend the unique possibilities of twisted polaritons discussed above to develop optical applications requiring propagation of the electromagnetic energy flow along specific directions, for example, directional coupling between molecules or quantum emitters or directional thermal management. − …”

Elevating Surface-Enhanced Infrared Absorption with Quantum Mechanical Effects of Plasmonic Nanocavities

“…This gap-dependent SEIRA not only shows the benefits of quantum mechanical effects of plasmonic nanocavities for the plasmonic enhanced optical process at mid-infrared frequencies but also indicates SEIRA as an ideal probe for examining the field enhancement of mid-infrared plasmonic nanocavities with precision as high as ∼1 Å. Moreover, the pronounced SEIRA, especially the case with a subnanometer gap, shows CdO as a promising mid-infrared plasmonic material, which recently has also been used for the design of mid-infrared thermal emitters with a narrow band . Our work demonstrates the new possibility of elevating the field enhancement and SEIRA sensitivity of mid-infrared plasmonic nanocavities and paves the way for novel design of plasmonic nanocavities with elevated SEIRA sensitivity.…”

“…The semiconducting CdO nanocrystal was chosen because of its prominent mid-infrared plasmonic responses (Supporting Information section S1). ,− Meanwhile, the plasmonic resonance of CdO nanocrystals could be readily tuned over a large frequency range via the particle size, based on the inverse scaling relationship between the carrier concentration and size . The gold nanoparticle was introduced to couple to the CdO nanocrystal in order to facilitate the immobilization of molecules.…”

Single‐Material, Near‐Infrared Selective Absorber Based on Refractive Index‐Tunable Tamm Plasmon Structure

“…Furthermore, the angular dependency with varying polarization was compared, which shows less dispersive properties under s-polarization, otherwise p-polarization light affects typically more dispersive (Figure S13, Supporting Information). [13,25,38] As exhibited in Figure S14 designed structure shows great angular dependency even under p-polarized light, which offers a promising applicability as a photo detection device (see Supporting Information). The angle insensitive performance could be explained by the fact that phase shift accumulated during the propagation through the DBR layers is relatively insignificant due to the small optical thickness of the DBR layers which originated from the high refractive indices of a-Ge/P r -75%.…”

“…Creating strongly coupled narrow absorption in the near infrared region is a critical requisite for investigating highly DBR and metal layer, they represented higher Q factor and thinner configuration than conventional case. [25][26][27] Nevertheless, the material selection limitation and the fact that N is tunable within an only integer range make perfect matching of Z difficult. Further, owing to the residual parasitic absorption that occurs in dielectric materials, increased N reduces the radiative loss and increases the nonradiative loss.…”