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

Lingjuan He, Linfang Shen, Xiaohua Deng, Kai Yuan,

https://iopscience.iop.org/article/10.1088/2040-8986/ab1bcd/pdf

Terahertz one-way edge modes in truncated photonic crystals (PhCs) are investigated theoretically. The PhC consists of a square array of air columns in semiconductor. By applying an external dc magnetic field in the PhC, a band gap is generated by lifting the degeneracy point of the lowest two bands. Based on this band gap, edge mode always exists in the truncated PhC for any boundary cutting, and it may propagate unidirectionally or bidirectionally, closely depending on the PhC boundary shape. It is shown that for one-way edge mode, the PhC boundary cutting has remarkable influence on the propagation length when the semiconductor loss is taken into account. A boundary structure is introduced into the PhC system for weakening the loss effect, and the propagation length of the one-way edge mode can be increased nearly by twice by optimizing the boundary parameters.

Abstract-Broadband one-way propagation and rainbow trapping of terahertz radiations

Jie Xu, Sanshui Xiao, Chiaho Wu, Hang Zhang, Xiaohua Deng, and Linfang Shen

Fig. 1 Schematics of the metal-semiconductor-dielectric-metal (a) and related semiconductordielectric-metal (b) structures for sustaining one-way SMPs. An external dc magnetic field is applied along the −y direction in the two structures.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-8-10659

Surface magnetoplasmon (SMP) supported at an interface between magnetized plasmonic and dielectric materials has been widely explored; however, it suffers with narrow bandwidth for one-way propagation. Here we propose a novel metal-semiconductor-dielectricmetal (MSDM) structure showing the large bandwidth for the complete one-way propagation (COWP). Because of the compression of the zone for two-way propagating modes in the semiconductor layer by reducing semiconductor thickness, the bandwidth is significantly increased by several times. More importantly, in such MSDM structure, the SMP dispersion can be engineered by controlling the semiconductor thickness, and based on this, slowing wave and trapping rainbow can be realized in a tapered system at terahertz frequencies.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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

Lingjuan He, Qian Shen, Jie Xu, Yun You, Tianbao Yu, Linfang Shen, Xiaohua Deng,

https://www.nature.com/articles/s41598-018-26395-4

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.

Abstract-Stopping terahertz radiation without backscattering over a broad band

Stopping terahertz radiation without backscattering over a broad band Linfang Shen, Xiaodong Zheng, and Xiaohua Deng  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-9-11790

Optics Express, Vol. 23, Issue 9, pp. 11790-11798 (2015)
http://dx.doi.org/10.1364/OE.23.011790

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We present an approach to completely stop terahertz radiation in an optical system with a gyroelectric semiconductor. This system is composed of guiding and stopping parts formed by the semiconductor with different cladding structures. Because the dispersion properties of surface magnetoplasmons (SMPs) in the semiconductor closely depend on its cladding structure, robust one-way SMPs sustained by the guiding part are prohibited in the stopping part, thereby stopping terahertz radiation without any backscattering. For incident continuous waves, trapped spots with strongly enhanced fields occur on a subwavelength scale. For incident pulses, the wave packets can be completely trapped and simultaneously compressed to subwavelength sizes.

© 2015 Optical Society of America

Abstract-Backscattering-immune one-way surface magnetoplasmons at terahertz frequencies

Backscattering-immune one-way surface magnetoplasmons at terahertz frequencies Linfang Shen, Yun You, Zhuoyuan Wang, and Xiaohua Deng  »View Author Affiliations

Optics Express, Vol. 23, Issue 2, pp. 950-962 (2015)
http://dx.doi.org/10.1364/OE.23.000950

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-2-950

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Surface magnetoplasmons (SMPs) in a basic physical model for the terahertz regime, which consists of a semi-infinite magnetized semiconductor with dielectric cladding terminated by a metal slab, are theoretically investigated. The dispersion properties of such SMPs are analyzed and examined in detail. It is shown that SMPs may follow three different kinds of dispersion diagrams, depending on the applied dc magnetic field intensity. Complete one-way propagation that operates within the band gap of the semiconductor is available for SMPs, and the one-way bandwidth reaches a maximum at a certain magnetic field intensity. Regular modes guided by the dielectric layer are also analyzed. These modes may cause the (complete) SMP one-way region to be compressed or even removed, but they can be suppressed by reducing the dielectric layer thickness. Owing to the mirror effect of the metal slab, one-way propagating and backscattering-immune basic SMPs can exhibit a larger propagation length than those sustained by a single dielectric–semiconductor interface.

© 2015 Optical Society of America

Abstract-Subwavelength guiding of channel plasmon polaritons in a semiconductor at terahertz frequencies

Fangming Zhu, Xiaoer Li, and Linfang Shen  »View Author Affiliations

http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-53-26-5896

Applied Optics, Vol. 53, Issue 26, pp. 5896-5900 (2014)
http://dx.doi.org/10.1364/AO.53.005896

We present a numerical investigation of terahertz channel plasmon polaritons (CPPs) propagating in a semiconductor InSb. It is shown that these CPPs can simultaneously exhibit subwavelength field confinement and relatively long propagation length. Moreover, single-mode propagation is available for terahertz CPPs in a certain frequency range.

© 2014 Optical Society of America

Abstract-Subwavelength guiding of channel plasmon polaritons in a semiconductor at terahertz frequencies

Fangming Zhu, Xiaoer Li, and Linfang Shen  »View Author Affiliations

http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-53-26-5896

Applied Optics, Vol. 53, Issue 26, pp. 5896-5900 (2014)
http://dx.doi.org/10.1364/AO.53.005896

We present a numerical investigation of terahertz channel plasmon polaritons (CPPs) propagating in a semiconductor InSb. It is shown that these CPPs can simultaneously exhibit subwavelength field confinement and relatively long propagation length. Moreover, single-mode propagation is available for terahertz CPPs in a certain frequency range.

© 2014 Optical Society of America