Superradiantly limited linewidth in complementary THz metamaterials on Si-membranes

• Main Authors: Keller, Janine, Haase, Johannes, Appugliese, Felice, Rajabali, Shima, Wang, Zhixin, Paravicini-Bagliani, Gian Lorenzo, Maissen, Curdin, Scalari, Giacomo, Faist1, Jérôme
• Format: Journal Article
• Language: English
• Published: 02-10-2019
• Subjects: Physics - Optics
• DOI: 10.48550/arxiv.1910.00814

Advanced Optical Materials 6, 16, 2018 We study complementary double split ring THz resonators fabricated on a 10
mum thin Si-membrane. The linewidths of the fundamental LC-mode and dipolar
mode are drastically narrowing with increased resonator spacing. The extracted
decay rate of the LC-mode as a function of the resonator density shows a linear
dependence, evidencing a collective superradiant effect of the resonator array.
Furthermore, we show that a metamaterial can be designed for a low superradiant
broadening of the resonance at high resonator densities, i.e. in the
metamaterial condition. The use of a thin membrane as a substrate is crucial,
since it shifts the THz surface plasmon polaritons modes to much higher
frequencies, preventing them to couple to the LC mode and unveiling the
superradiant broadening mechanism for a large range of lattice spacings. At
higher frequencies, not interfering with the high Q LC-mode, other additional
modes, which we ascribe to photonic crystal modes, form in the Si-membrane. We
map the angle dependent band structure and show corresponding simulated
electric field distributions.