Nanoimaging and Nanospectroscopy of Polaritons with Time Resolved s‐SNOM

Abstract

The development of electronics and photonics is entering a new era of ultrahigh speed sensing, data processing, and telecommunication. The carrier frequencies of the next‐generation electronic devices inevitably extend beyond radio frequencies, marching toward the nominally photonics‐dominated territories, e.g., terahertz and beyond. As a result, electronic and photonic techniques naturally merge and seek common ground. At the forefront of this technical trend is the field of polaritonics, where polaritons are half‐light, half‐matter quasiparticles that carry the properties of both “bare” photons and “bare” dipole‐carrying excitations. The Janus‐faced nature of polaritons renders the unique capability of operando control using photoexcitation or applied electric field. Here, state‐of‐the‐art ultrafast polaritonic phenomena probed by scattering‐type scanning near‐field optical microscope (s‐SNOM) techniques is reviewed. The ultrafast dynamical control and loss‐reduction of the polariton propagation are discussed with special emphasis on the creation and probing of the tip or edge induced plasmon– and phonon–polaritons in low‐dimensional systems. The detailed technical aspects of s‐SNOM and its possible future development are also presented.

Ultrafast Coherence Delocalization in Real Space Simulated by Polaritons

“…When molecular vibrational modes are strongly coupled to the cavity modes, they form hybridized quasiparticles–molecular vibrational polaritons. [ 17–40 ] Using a coupled dual‐cavity polariton platform, [ 17 ] we previously demonstrated that nonlinear interactions in the system can be delocalized, through exciting the dark state populations. However, it is insufficient to realize coherence transfer because, unlike dark states, polariton coherences are much shorter lived and are vulnerable to solvent fluctuations across spaces.…”

Polariton panorama

“…Nonlinear [352][353][354] and quantum [355][356][357][358][359] properties of plasmonic structures are in the vanguard of current research. Plasmon polaritons can be controlled at femto-second timescales [67,267,[360][361][362][363] enabling access to novel physics and applications [364,365]. Plasmonic waveguides have been incorporated with light-emitting materials, paving the way for integrated plasmonic and photonic structures [366].…”

Recent advances in terahertz imaging: 1999 to 2021

“…Researchers have branched out to explore the possibilities offered by other terahertz sources, both pulsed and continuous-wave [98][99][100]. Meanwhile, the first report of time-resolved pump-probe experiments coupled to an apertureless s-SNOM [101] has inspired interest in studying terahertz photophysics with both femtosecond temporal resolution and nanometer-scale spatial resolution [102,103]. Several other variations of these experiments have been reported.…”