Unidirectional invisibility induced by parity-time symmetric circuit

Abstract

Parity-time (PT) symmetric structures present the unidirectional invisibility at the spontaneous PT-symmetry breaking point. In this paper, we propose a PT-symmetric circuit consisting of a resistor and a microwave tunnel diode (TD) which represent the attenuation and amplification, respectively. Based on the scattering matrix method, the circuit can exhibit an ideal unidirectional performance at the spontaneous PT-symmetry breaking point by tuning the transmission lines between the lumped elements. Additionally, the resistance of the reactance component can alter the bandwidth of the unidirectional invisibility flexibly. Furthermore, the electromagnetic simulation for the proposed circuit validates the unidirectional invisibility and the synchronization with the input energy well. Our work not only provides an unidirectional invisible circuit based on PT-symmetry, but also proposes a potential solution for the extremely selective filter or cloaking applications.

Microwave Tunneling and Robust Information Transfer Based on Parity-Time-Symmetric Absorber-Emitter Pairs

“…Here, we experimentally prove that, by placing a shunt lossy element in the transmitting node before the obstacle and a judiciously designed gain element in the receiving node, forming a PT-symmetric conjugate pair [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], we can restore full transmission at the operational frequency, despite the presence of a nearly unitary reflective obstacle blocking the transmission channel. The obstacle in our experiment is modeled as a shorting element along a transmission line.…”

PT-symmetry and supersymmetry: interconnection of broken and unbroken phases

“…The prospect of using both optical gain and loss has emerged as a new paradigm in shaping the flow of light. These include effects like unidirectional invisibility [46], loss-induced transparency [7], band merging [47], optically induced atomic lattices [48] and improved lasing as mentioned earlier. The exceptional points (EPs) have emerged as a new design tool for engineering the response of optical systems, as near these points, light propagation has a strong parameter sensitivity, which is further affected by subtle changes in the initial condition [49].…”

Photonic Topological Insulating Phase Induced Solely by Gain and Loss

“…Our scheme is experimentally feasible by modifying the existing laser arrays with controlled optical pumping [46][47][48] and valid for coupled waveguides [44,45]. Moreover, it can be explored as an extension of PT -symmetric setups in photonics [10,18,[22][23][24][25][26]43], phononics [71][72][73], and circuit electronics [74,75]. It would pave the way for various possibilities of non-Hermitian topological photonics, such as reconfigurable topological lasing states, non-Hermiticity-based topological pumping [41,76], topological superstructures [77] and Floquet topological systems [40,78].…”