Real-space imaging of nanoplasmonic resonances

Abstract

Resonant nanoplasmonic structures have long been recognized for their unique applications in subwavelength control of light for enhanced transmission, focussing, field confinement, decay rate management, etc. Increasingly, they are also integrated in electro-optical analytical sensors, shrinking the active volume while at the same time improving sensitivity and specificity. The microscopic imaging of resonances in such structures and also their dynamic variations has seen dramatic advances in recent years. In this Minireview we outline the current status of this rapidly evolving field, discussing both optical and electron microscopy approaches, the limiting issues in spatial resolution and data interpretation, the quantities that can be recorded, as well as the growing importance of time-resolving methods.

Circular optical nanoantennas: an analytical theory

“…Eigenmodes of various nanoantennas have been measured by different means [17][18][19][20][21][22][23][24][25] . However, problematic in further advancing the field is the lack of analytical insight into the scaling behavior of optical nanoantennas to carefully design them for a desired application [26][27][28][29][30] .…”

Imaging of rectified plasmonic fields on nanoantennas with single nanometer precision

“…For example, indirect measurement techniques such as photoemission electron microscopy (PEEM), 3,4 electron energy-loss spectroscopy (EELS), 3,5 and cathodoluminescence (CL) 3,5 are powerful, yet limited. PEEM relies on the photoemission of electrons from the surface/structure, while EELS involves the detection of electron energy losses and CL requires emitted radiation to be captured.…”

“…6 These methods require high vacuum and complex detection equipment, making them impractical for many situations. Direct methods include photon scanning tunneling microscopy (PSTM) 3,7,8 and both aperture and scattering near-field scanning optical microscopy (NSOM). 3,9,10 These techniques involve probing the structure, however they are limited by the probe's aperture diameter or tip apex radius, and thus, the direct methods are limited to ~10nm resolution.…”

Self-assembled plasmonic metamaterials

“…On the other hand, techniques with high spatial resolution can be used to explore the characteristics of the isolated unit cell. Whereas the ensemble can usually only be characterized in the farfield, and the necessary techniques are summarized as whole-field techniques, in the latter strategy that probes the properties of individual unit cells, information can be acquired in the far-field but also in the near-field [ 148 ]. Due to this distinction this chapter is divided into two sections.…”