Giant tunable Goos–Hänchen shifts based on surface plasmon resonance with Dirac semimetal films

Abstract

Surface plasmon resonance (SPR) with bulk Dirac semimetals (BDS) has been proposed to enhance the Goos-Hänchen (GH) shift. It is found that a large positive and negative GH shift can be obtained by adjusting the thickness of the BDS film, and the GH shift is very sensitive to the Fermi level of the BDS film. By changing the Fermi level of the BDS film, we can get a controllable negative GH shift. The largest GH shift of the proposed configuration, as large as 361.4 times the incident wavelength, has been obtained. Compared with the traditional SPR structure, the GH shift is increased by nearly 13.4 times, which indicates that BDS is expected to replace the traditional SPR structure to excite the stronger SPR. Finally, the numerical simulation results further verify that the giant shift can be obtained by a finite width Gaussian beam in our proposed calculation. Based on this giant and controllable GH shift, it may have potential applications in tunable sensors, switches, filters, and other devices.

Mid-Infrared Sensor Based on Dirac Semimetal Coupling Structure

“…In the traditional Au (Ag) sensor, we used an excitation wavelength of 632.8 nm, Au (Ag) film thickness of 45 nm, and n Au = 0.7900 + 17.3109i, n Ag = 0.1675 + 3.4728i. The parameters are consistent with previous studies [ 21 , 52 , 53 ]. When the refractive index of the sensing medium changes 0.002, the GH shifts changed by 51.7 .According to Equation (12), the sensitivity can be obtained as S n .…”

“…Previous studies have shown that the conductivity of the DSM can be described by the Kubo formula [ 21 , 43 ]. For and long-wavelength limit, the optical conductivity can be written analytically as where g is the degeneracy factor, is the Fermi velocity, is the step function, and represents the high-energy cutoff of the linear model.…”

“…Additionally, the semi-metallic nature of DSM makes it highly promising. In the mid-infrared to terahertz band, DSM and graphene have a dielectric constant below zero, which can excite surface plasmon resonance (SPR) with less loss than conventional metals (e.g., Ag and Au) and is expected to be an excellent candidate for SPR [ 20 , 21 ]. Like graphene, its tunability is more prominent [ 22 , 23 , 24 ], and its thickness can be freely tailored to ensure stronger light-matter interactions.…”

Electrically Tunable Singular Phase and Goos–Hänchen Shifts in Phase‐Change‐Material‐Based Thin‐Film Coatings as Optical Absorbers

“…[21][22][23] Since the optical properties of graphene can be tuned by changing its chemical potential or Fermi energy, several graphene-based optical systems have been theoretically, and numerically demonstrated the tuning of G-H shifts. [24][25][26][27][28][29][30][31][32] Moreover, tunable G-H shift has been theoretically and numerically investigated in several optical systems such as Dirac semimetal films by exciting the SPs, [33] a cavity with four-level quantum system, [34] a weakly absorbing epsilon-near-zero slab [27] and a nanocomposite structurally chiral medium. [35] In addition, the forward tuning of G-H shift in the visible wavelengths (with maximum and minimum values only) has been experimentally demonstrated using a PCM-based HMM by directly annealing the HMM at higher temperature [36,37] (280 °C).…”

Enhancing Goos-Hänchen shift based on magnetic dipole quasi-bound states in the continuum in all-dielectric metasurfaces

“…A high Q-factor resonance also leads to dramatic change in the reflection phase around the resonant peak 41 . Based on these, numerous theoretical and experimental works have been devoted to enhancing the GH shift on different structure interfaces such as weakly absorbing slab [42][43][44] , surface plasmon resonator [45][46][47][48] , Bloch surface wave resonator [49][50][51] , dielectric metagrating and photonic crystal slab 52,53 . However, there is a common defect in these two enhancement mechanisms: although the maximum GH shift can be enhanced to the length of orders of wavelength, it is exactly located at the reflection dip with extremely low reflectance, which is difficult to be detected.…”