|Title||Broadband terahertz generation from metamaterials|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Luo, L, Chatzakis, I, Wang, JG, Niesler, FBP, Wegener, M, Koschny, T, Soukoulis, CM|
|Type of Article||Article|
|Keywords||negative refractive-index, pulses, quantum-cascade lasers, technology, thz|
The terahertz spectral regime, ranging from about 0.1-15 THz, is one of the least explored yet most technologically transformative spectral regions. One current challenge is to develop efficient and compact terahertz emitters/detectors with a broadband and gapless spectrum that can be tailored for various pump photon energies. Here we demonstrate efficient single-cycle broadband THz generation, ranging from about 0.1-4 THz, from a thin layer of split-ring resonators with few tens of nanometers thickness by pumping at the telecommunications wavelength of 1.5 mm (200 THz). The terahertz emission arises from exciting the magnetic-dipole resonance of the split-ring resonators and quickly decreases under off-resonance pumping. This, together with pump polarization dependence and power scaling of the terahertz emission, identifies the role of optically induced nonlinear currents in split-ring resonators. We also reveal a giant sheet nonlinear susceptibility similar to 10(-16) m(2) V-1 that far exceeds thin films and bulk non-centrosymmetric materials.
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