Trapping and releasing bidirectional rainbow at terahertz frequencies

Xu, Jie; Shen, Qian; Yuan, Kai; Deng, Xiaohua; Shen, Yun; Zhang, Hang; Wu, Chiaho; Xiao, Sanshui; Shen, Linfang

doi:10.1016/j.optcom.2020.125999

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…It is really meaningful if the POB theory revealed above can be applied in the terahertz regime. As we reported in previous works [6,7,9], the COWP band may be narrowed down or even vanish in sub-wavelength one-way terahertz waveguides. Moreover, to our knowledge, the INZ modes have never been reported in the one-way terahertz waveguide sandwiched by metals.…”

Section: The Inz Mode-based Pob In the Terahertz Regimesupporting

confidence: 67%

“…In our previous works [6,7,9,41], cutting off the magnetic-optical (MO) material has been proved to be an efficient way to engineer the dispersion of the EM modes (e.g., SMPs) in the nonreciprocal systems. In this paper, we will show how such technique can be used to achieve broadband index-near-zero modes.…”

Section: Slowed Down Unidirectional Smpsmentioning

confidence: 99%

“…Tsakmakidis's group demonstrated that in the MO heterostructure the time-bandwidth limit, which was believed to be a fundamental limit in both engineering and theory, can be overcome due to the broken Lorentz reciprocity [2]. More recently, our group reported several MO-based one-way nonreciprocal waveguides where many interesting phenomena such as slow wave [6], truly trapping of robust unidirectional rainbow [7,8] and bidirectionally slowed down rainbow trapping and releasing [9] were illustrated. It is inspiring to use the simple powerful MO heterostructure to demonstrate novel devices with new functionalities.…”

Section: Introductionmentioning

confidence: 99%

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Realization of broadband index-near-zero modes in nonreciprocal magneto-optical heterostructures

Zhou,

He,

Xiao

et al. 2022

Preprint

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Epsilon-near-zero (ENZ) metamaterial with the relative permittivity approaching zero has been a hot research subject in the past decades. The wave in the ENZ region has infinite phase velocity (v = 1/ √ εµ), whereas it cannot efficiently travel into the other devices or air due to the impedance mismatch or near-zero group velocity. In this paper, we demonstrate that the tunable index-nearzero (INZ) modes with vanishing wavenumbers (k = 0) and nonzero group velocities (v g = 0) can be achieved in nonreciprocal magneto-optical systems. This kind of INZ modes has been experimentally demonstrated in the photonic crystals at Dirac point frequencies and that impedance-matching effect has been observed as well. Our theoretical analysis reveals that the INZ modes exhibit tunability when changing the parameter of the one-way (nonreciprocal) waveguides. Moreover, owing to the zero-phase-shift characteristic and decreasing v g of the INZ modes, several perfect optical buffers (POBs) are proposed in the microwave and terahertz regimes. The theoretical results are further verified by the numerical simulations performed by the finite element method. Our findings may open the new avenues for research in the areas of ultra -strong or -fast nonlinearity, perfect cloaking, high-resolution holographic imaging and wireless communications.

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Section: The Inz Mode-based Pob In the Terahertz Regimesupporting

confidence: 67%

Section: Slowed Down Unidirectional Smpsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Realization of broadband index-near-zero modes in nonreciprocal magneto-optical heterostructures

Zhou,

He,

Xiao

et al. 2022

Preprint

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“…[38] In 2017, we found that owing to the one-way property, the MO heterostructure terminated by metal layers could overcome the time-bandwidth limit because of the broken Lorentz reciprocity. [31] Recently, we have proposed several MO one-way waveguides in which interesting functionalities such as slow light, [30,39] bidirectionally rainbow trapping and releasing, [40] and true rainbow trapping [32,41] were achieved. The one-way propagation characteristic is very suitable and desired for designing LGs because the one-way modes are insensitive to disorders and bends, [42,43] and the noise barely exists in such devices.…”

Section: Introductionmentioning

confidence: 99%

All‐Optical Digital Logic Based on Unidirectional Modes

Luo

Xiao

et al. 2022

Advanced Optical Materials

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Standard electronic computing based on nanoelectronics and logic gates has upended our lives in a profound way. However, suffering from, both, Moore's law and Joule's law, further development of logic devices based solely on electricity has gradually stuck in the mire. All‐optical logic devices are believed to be a potential solution for such a problem. This work proposes an all‐optical digital logical system (AODLS) based on unidirectional (one‐way propagation) modes in the microwave regime. In a Y‐shaped module of the AODLS, the basic seven logic gates, including OR, AND, NOT, NOR, NAND, XOR, and XNOR gates, are achieved for continuous broadband operation relying on the existence of unidirectional electromagnetic signals. Extremely large extinction and contrast ratios are found in these logic gates. The idea of “negative logic” is used in designing the AODLS. Moreover, the authors further demonstrate that the AODLS can be assembled to multi‐input and/or multi‐output logical functionalities, which is promising for parallel computation. Besides, numerical simulations perfectly fit with and corroborate the theoretical analyses presented here. The low‐loss, broadband, and robust characteristics of this system are outlined and studied in some detail. The AODLS consisting of unidirectional structures may open a new route for all‐optical calculation and integrated optical circuits.

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