Dependence of guided resonances on the structural parameters of terahertz photonic crystal slabs

Abstract

Using terahertz spectroscopy, we measure the normal-incidence transmission coefficient of photonic crystals consisting of a periodic lattice of air holes in a silicon slab. Sharp resonant features are observed in the transmission spectra due to coupling of the leaky photonic crystal modes, called guided resonances, to the continuum of free-space modes. The resonances show considerable sensitivity to the structural parameters of the slab, including the slab thickness. By varying each crystal parameter systematically, we study the dependence of the resonances on the geometry of the photonic crystal slabs. Even small changes in a parameter such as the slab thickness, for example, can lead to dramatic changes in the optical spectrum. We also compare the transmission spectrum of a photonic crystal slab with a hexagonal lattice to that of a slab with a square lattice. In most cases, the experimental results match very well with numerical simulations based on the finite element method.

Parametric study of guided resonances in octagonal photonic quasicrystals

“…In the periodic case [19], besides the changes in the Fabry-Perot background (in view of the changes in the effective refraction index), increasing the air/dielectric fraction (i.e., increasing the hole radius) was found to produce a shift of the GRs towards higher frequencies.…”

State conversion based on terahertz plasmonics with vanadium dioxide coating controlled by optical pumping

“…2(b), there is a strong frequency dip located at 0.87 THz. This dip originates from the guided resonance for the out of plane propagation through PC, which can be explained by Fano resonance model [15,16]. The transmittances under 1.5 W pumping are slightly lower than that of 0 W, and this weak decline is from the carrier effect on the Si surface.…”

Terahertz Sensor Using Photonic Crystal Cavity and Resonant Tunneling Diodes

“…A PC is composed of dielectric materials with a periodic refractive index distribution. In the THz region, PC slabs [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and their applications such as planar low-loss waveguide have been demonstrated [32]. High-Q THz PC micro-cavities (approximately 1000-9000) [25,29,30,34] and their applications in sensing have been recently reported [30,34].…”