Mezzapesa Francesco P, Columbo Lorenzo L, Rizza Carlo, Brambilla Massimo, Ciattoni Alessandro, Dabbicco Maurizio, Vitiello Miriam S, Scamarcio Gaetano
Dipartimento Interateneo di Fisica, Università degli Studi e Politecnico di Bari, via Amendola 173, I-70126 Bari Italy.
CNR-IFN UOS Bari, via Amendola 173, I-70126 Bari Italy.
Sci Rep. 2015 Nov 9;5:16207. doi: 10.1038/srep16207.
Periodic patterns of photo-excited carriers on a semiconductor surface profoundly modifies its effective permittivity, creating a stationary all-optical quasi-metallic metamaterial. Intriguingly, one can tailor its artificial birefringence to modulate with unprecedented degrees of freedom both the amplitude and phase of a quantum cascade laser (QCL) subject to optical feedback from such an anisotropic reflector. Here, we conceive and devise a reconfigurable photo-designed Terahertz (THz) modulator and exploit it in a proof-of-concept experiment to control the emission properties of THz QCLs. Photo-exciting sub-wavelength metastructures on silicon, we induce polarization-dependent changes in the intra-cavity THz field, that can be probed by monitoring the voltage across the QCL terminals. This inherently flexible approach promises groundbreaking impact on THz photonics applications, including THz phase modulators, fast switches, and active hyperbolic media.
半导体表面光激发载流子的周期性模式会深刻改变其有效介电常数，从而形成一种静态的全光准金属超材料。有趣的是，人们可以调整其人工双折射，以前所未有的自由度来调制受这种各向异性反射器光反馈作用的量子级联激光器（QCL）的幅度和相位。在此，我们构思并设计了一种可重构的光设计太赫兹（THz）调制器，并在一个概念验证实验中利用它来控制太赫兹量子级联激光器的发射特性。通过光激发硅上的亚波长亚结构，我们在腔内太赫兹场中诱导出与偏振相关的变化，这可以通过监测量子级联激光器终端两端的电压来探测。这种本质上灵活的方法有望对太赫兹光子学应用产生突破性影响，包括太赫兹相位调制器、快速开关和有源双曲线介质。
