Generation of two-dimensional plasmonic bottle beams

Abstract

By analogy to the three dimensional optical bottle beam, we introduce the plasmonic bottle beam: a two dimensional surface wave which features a lattice of plasmonic bottles, i.e. alternating regions of bright focii surrounded by low intensities. The two-dimensional bottle beam is created by the interference of a non-diffracting beam, a cosine-Gaussian beam, and a plane wave, thus giving rise to a non-diffracting complex intensity distribution. By controlling the propagation constant of the cosine-Gauss beam, the size and number of plasmonic bottles can be engineered. The two dimensional lattice of hot spots formed by this new plasmonic wave could have applications in plasmonic trapping.

Plasmonic metalens based on coupled resonators for focusing of surface plasmons

“…In the last decade, with the development of subwavelength optics and fabrication technologies, manipulating SPs by artificial structured surfaces (metasurfaces) has garnered a lot of attention567. For instance, a series of SP-based applications have been demonstrated by metasurfaces, including SP metalenses891011, unidirectional launchers12131415, wavelength demultiplexers1617181920, special SP beams2122232425 and SPs wavefront engineering26. Among these, metalenses have been intensively explored in recent years since they can couple free-space electromagnetic waves to SPs and then focus them to spatial regions that are much smaller than the diffraction limit.…”

Dynamic generation of plasmonic bottle-beams with controlled shape

“…The concept of the bottle-beam was originally proposed for trapping of particles with a refractive index lower than the surrounding medium, by the gradient force, which is directed toward the low-intensity region, i.e., "inside the bottle," or cold atoms using bluedetuned radiation [3]. Another possibility is to trap and guide high-index particles along the surface of the bottle, which is characterized by high intensity.Since then, many kinds of free-space optical bottlebeams have been demonstrated and by different methods, such as axicon-based methods [4-6], dynamic generation [7,8], holography-based methods [9,10], laser generation [11,12], 3D abruptly autofocusing beams [13], moiré techniques [14], 3D volume bottle-beams [15], and many more. The generation of bottle-beams was also extended recently to plasmonic surface beams; for example, 2D plasmonic bottle-beams were generated by interfering a plasmonic cosine-Gauss beam with a surface plasmon plane wave [16] or interfering two plasmonic cosine-Gauss beams [17].…”

“…A beam that propagates with an arbitrary convex caustic curve, over a finite distance, can be constructed by defining the initial transverse phase ϕ i y, at the input plane z 0. The relation between the initial phase, ϕ i y ϕy; z 0, and the caustic trajectory, f z, can be expressed mathematically by [15] dϕ i y dy kf 0 z 1 f 0 z 2 p ;(1)where f 0 z df z∕dz and k is the wave vector. From Eq.…”

“…Since then, many kinds of free-space optical bottlebeams have been demonstrated and by different methods, such as axicon-based methods [4-6], dynamic generation [7,8], holography-based methods [9,10], laser generation [11,12], 3D abruptly autofocusing beams [13], moiré techniques [14], 3D volume bottle-beams [15], and many more. The generation of bottle-beams was also extended recently to plasmonic surface beams; for example, 2D plasmonic bottle-beams were generated by interfering a plasmonic cosine-Gauss beam with a surface plasmon plane wave [16] or interfering two plasmonic cosine-Gauss beams [17].…”

“…This curve can be constructed by multiple geometrical rays, which are tangent to the curve itself [15,22]. A beam that propagates with an arbitrary convex caustic curve, over a finite distance, can be constructed by defining the initial transverse phase ϕ i y, at the input plane z 0.…”