Giant Goos-Hänchen shifts controlled by exceptional points in a PT-symmetric periodic multilayered structure coated with graphene

Abstract

We theoretically study the Goos-Hänchen (GH) shifts of Gaussian beams reflected in parity-time (PT) symmetric multilayered structure coating graphene structures. And there are the exceptional points (EPs) in this structure, whose position can be adjusted by the real part of the dielectric constant and the incident angle. Moreover, we find that the value and direction of the GH shifts change significantly under different EPs, so we could control the GH shifts by the position of the EPs. When the dielectric constant is fixed, the GH shifts can also be adjusted by the Fermi energy of graphene and the period number of the PT-symmetric structure. With the increase of the period number of the PT system, the system will produce the Bragg resonance, which refers to the phenomenon of total reflection caused by the interaction between the wave and the periodic structure with a specific frequency. And at the Bragg resonance, the special GH shifts independent of the incident direction can be obtained with large reflectivity. In addition, the incident direction of the beam can also affect the GH shifts in this asymmetric structure. Our results may find great applications in highly sensitive sensors, optoelectronic switches, and all-optical devices.

Goos–Hänchen and Imbert–Fedorov shifts of the Airy beam in dirac metamaterials

“…Based on the definition of GH and IF shifts, they refer to the shifts of the reflected beam from the path normally expected by geometrical optics along the x-and y-axis respectively [5]. With the development of novel materials and structures, the GH and IF shifts can be enhanced and modulated effectively in various materials, such as graphene [6][7][8][9][10][11], weakly absorbing dielectric [12][13][14][15], photonic crystal [16][17][18], plasmonics [19,20] and nonoptical systems [21][22][23][24][25]. In addition, the GH and IF shifts have potential applications in optical sensors [26,27], image edge detection [28] and optical switches [29,30].…”

Polarization-independent enhanced and tunable Goos-Hänchen shift in a metal-dielectric grating structure with monolayer graphene

“…The GH shift is of great application value in the fields of sensing and detection because it is very sensitive to the small changes in geometric parameters [15,16]. With the appearance of monolayer graphene, many researchers have conducted the extensive studies on the GH shifts in monolayer graphene-based systems, including the dielectric slabs, the prism-coupled structures, multilayer structures and the grating structures [17][18][19][20][21]. For example, Liu et al have proposed a bimetal structure based on monolayer graphene-hexagonal boron nitride to obtain a large GH shift about 182.09 times of the incident wavelength (182.09λ) by the excitation of surface plasmon polariton (SPP) on the surface of the metallic medium under the transverse magnetic (TM) polarized wave [22].…”