One-way edge modes in a photonic crystal of semiconductor at terahertz frequencies

Abstract

Electromagnetic edge mode in a photonic crystal (PhC), which is a square array of semiconductor rods in air, is theoretically investigated for terahertz frequencies. In the PhC, gyroelectric anisotropy is introduced in the semiconductor rods by applying an external magnetic field and consequently, a degeneracy point, at which two dispersion surfaces intersect, is lifted and a new band gap is created. The edge mode sustained by the PhC possesses the character of one-way propagation, and it even can be immune to backscattering at large defect on the wavelength scale and 90° sharp bend. The properties of the one-way mode are closely dependent on the cladding layer structure of the PhC.

One-way edge modes in truncated semiconductor photonic crystal at terahertz frequencies

“…the magnetic field is parallel to the external magnetic field), where k 0 is the vacuum wavenumber and v e is the Voigt permittivity, which is defined by . The value of v e is found to be 0.23 for f 3.1 THz = [20]. The bulk modes for the E polarization (i.e.…”

“…As the band gap of a PhC is adjustable by properly changing the lattice constant, one-way edge modes in PhCs have a remarkable advantage over the one-way SMPs. Very recently, it has been reported that a terahertz one-way edge mode can be realized in the PhC which is an array of semiconductor rods in air, and the operation range lies outside the band gap of the semiconductor itself [20]. In the present paper, a new type of PhC which operates at terahertz frequencies is proposed and investigated theoretically.…”

“…The optimal radius of the air column is r=0.21a, where a is the lattice constant. Once the external dc magnetic field is applied along the axis of the air column, the semiconductor becomes gyroelectrically anisotropic, whose (relative) permittivity has the form of [16,18,20] i i (where N, e, and m * are the density, charge and effective mass of the free carriers, respectively, and ε 0 is the vacuum permittivity) is the bulk plasma frequency, ν is the scattering frequency, eB m c 0 * w = / is the cyclotron frequency, and ε ∞ is the highfrequency (relative) background permittivity of the semiconductor. To analyze the dispersion properties of PhC as well as its edge mode, the semiconductor is first assumed to be lossless (i.e., v 0 = ), in order to distinguish the propagating mode (with real propagation constant) from the evanescent mode (with a complex propagation constant).…”

Nonreciprocal terahertz beam steering based on magneto-optic metagratings

“…18 experimentally observed an interference-induced transparency effect in InSb, which shows its good magnetic tunability in the THz regime. Shen’s group proposed the broadband THz one-way transmission based on the MO photonic crystal and MO plasmonic structures 19,20 . Recently, we also experimentally reported a THz nonreciprocal circular dichroism and Faraday effect of over 90° rotation angle under a weak magnetic field 20 , which can be used as THz MO polarization convertor and modulator.…”

Design of terahertz reconfigurable devices by locally controlling topological phases of square gyro-electric rod arrays

“…ge states exist e reversal sym ry for the gyro cal or microwa in semiconduc h a relatively s gical devices b osed [25]. Sim al [26].…”