In this paper, we demonstrate an electrically tunable double epsilon-near-zero (D-ENZ) metasurface by incorporating an ultra-thin indium-tin-oxide layer (≈ 5 nm) into an array of moderately-doped silicon (Si) nanobars. The D-ENZ phenomenon is achieved by accumulation and depletion of carrier densities in ITO and Si active layers under applying the external bias voltages. An active dual-band amplitude modulator is proposed which can realize the modulation depths of 0.86 and 0.71 at operating channels of λ 1 = 1547 nm and λ 2 = 1564.2 nm, leveraging the D-ENZ mechanism. The reasonably low intrinsic loss in such an optical device gives us the opportunity to have continuous amplitude modulation at both operating wavelengths without the necessity of a complicated multi-resonator unit-cell.

中文翻译：

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具有双ε接近零的超颖表面的可调双频带幅度调制

在本文中，我们通过将超薄铟锡氧化物层（≈5 nm）掺入中等掺杂的硅（Si）纳米棒阵列中，展示了电可调谐双epsilon-near-zero（D-ENZ）元表面。 。D-ENZ现象是通过在施加外部偏置电压的情况下在ITO和Si有源层中积累和耗尽载流子密度来实现的。提出了一种有源双波段调幅器，利用D-ENZ机制，可以在λ1 = 1547 nm和λ2 = 1564.2 nm的工作信道上实现0.86和0.71的调制深度。在这样的光学设备中，本征损耗相当低，这使我们有机会在两个工作波长上进行连续的幅度调制，而无需复杂的多谐振器晶胞。