Infrared Open Cavities for Strong Vibrational Coupling

Abstract

Arrays of subwavelength plasmonic nanoparticles exhibiting narrowband lattice resonances are referred to as open cavities because of their ability to strongly couple with electronic excitations in molecular chromophores. However, realization of these ideas in the mid-infrared spectral region has been limited. We demonstrated a dramatic reduction in the bandwidth of lattice resonances in large-area arrays of half-wavelength mid-infrared antennas, reaching resonance quality factors above 200. By tuning the wavelength of the antenna-lattice resonances (ALR) to match the transition frequency of the molecular vibrational modes, we achieved a strong coupling between the ALR and the carbonyl stretching excitation in a thin film of (poly)­methyl methacrylate (PMMA) polymer deposited on the array. Splitting of the polaritonic transitions, reduction of their bandwidth below that of the bare molecular transition, and characteristic dispersion confirmed the strong coupling regime. Our results pave the way for exciting research on the many-body correlated dynamics of vibrational polaritons.

Isolating Polaritonic 2D-IR Transmission Spectra

“…Other dynamical signatures of nonpolaritonic contributions may aid in identifying processes such as energy transfer to and from the dark reservoir. These findings also suggest that nanophotonic resonances may offer a notable advantage due to the potential to achieve strong coupling with single molecules. , …”

“…These findings also suggest that nanophotonic resonances may offer a notable advantage due to the potential to achieve strong coupling with single molecules. 51,52 ■ ASSOCIATED CONTENT * sı Supporting Information…”

Chasing Vibro-Polariton Fingerprints in Infrared and Raman Spectra Using Surface Lattice Resonances on Extended Metasurfaces

“… 28 Recently, VSC has been also demonstrated in two-dimensional periodic arrays of resonant scatterers. 29 These periodic systems sustain surface lattice resonances (SLRs). SLRs are the collective response of the scatterers in the array, mediated by the enhanced radiative coupling due to in-plane diffraction orders or Rayleigh anomalies (RAs).…”

Vibrational Polaritons in Disordered Molecular Ensembles

“…Experimentally, an open cavity was constructed with a high-quality antenna-lattice resonance (ALR) of the half-wavelength infrared antenna array, 38 , 39 where individual dipolar antenna resonances couple to the in-plane lattice diffraction order. 40 , 41 Unlike the commonly used Fabry–Perot-style optical cavities, in our experiments, the optical extinction occurs only at the ALR frequency while the nearby spectral region remains transparent, thus allowing direct spectroscopic access both to the polaritons and to the reservoir transitions.…”

“…The dispersion of the vibrational polaritons measured for different incident angles, shown in Figure 2 c, features an avoided crossing between the ALR and the CO modes at around in neat n -octane and that at in neat 1-chlorobutane. To compensate for the solvent-induced shift of the CO mode frequency and to maintain the resonant conditions, the ALR transition was tuned without affecting the ALR quality by slightly changing the angle of the TM-polarized incident light 39 with a precision goniometer, as shown in Figure S3 of the Supporting Information .…”