您当前的位置: 首页 > 网页快照
120, 087401 (2018) - Nonreciprocal Gain in Non-Hermitian Time-Floquet Systems
Images.
Figure 1.
Non-Hermitian time-Floquet system under study. Two coupled resonators with resonant frequencies ω1 and ω2 are connected to ports 1 and 2, with lifetimes 1/γ1 and 1/γ2. The complex internal coupling coefficient K(t) is time dependent, with K(t)=k0+Δk′cos(Ωt)+jΔk′′sin(Ωt).
Reuse & Permissions
Figure 2.
Excited Floquet amplitudes for incidence at ω1 from port 1. We represent the amplitudes of the three dominant Floquet harmonics in the first (orange) and second (blue) resonators for two different (arbitrary) values of Δk′, and for (a) Δk′′=0 and k0≠0, (b) Δk′′=0 and k0=0, (c) Δk′=Δk′′ and k0≠0, and (d) Δk′=Δk′′ and k0=0.
Reuse & Permissions
Figure 3.
Nonreciprocal gain in non-Hermitian time-Floquet systems. We plot the magnitude of the transmission coefficients to demonstrate the highly nonreciprocal behavior of the system. S210 and S21+ correspond to the transmissions to port 2, respectively, at ω1 and ω2, when a signal at ω1 is incident on port 1. S120 and S12? correspond to the transmissions to port 1, respectively, at ω2 and ω1, when a signal at ω2 is incident on port 2. We compare the (reciprocal) Hermitian time-Floquet system with (a) Δk′′=0 and k0=0 to the (nonreciprocal) non-Hermitian time-Floquet system (b) Δk′=Δk′′ and k0=0. Transmission through any other frequency channel is identically zero.
Reuse & Permissions
Figure 4.
Full-wave finite-element demonstration of non-reciprocal gain at microwave frequencies. The system is made of two microstrip ring resonators connected with a time-modulated capacitor in series with a time-modulated resistor [51]. (a) Spectrum of the scattering parameters demonstrating strong nonreciprocity and one-way amplification in a non-Hermitian time-Floquet system made of coupled split-ring resonators at f1. Panels (b) and (c) correspond to incidence on port 1 at ω1 and show the vertical electric field component at ω1 and ω2, respectively. (d),(e) Same as (b) and (d) for incidence on port 2. All panels are plotted with the same scale, where blue correspond to a negative field and red to a positive field.
Reuse & Permissions
×.
From: