Resonant terahertz radiation from Tl2Ba2CaCu2O8+δ thin films by ultrafast optical pulse excitation

Abstract

We have observed the free-space radiation of the resonant terahertz wave from c-axis oriented Tl 2 Ba 2 CaCu 2 O 8ϩ␦ thin films by femtosecond optical pulse excitation under a radial magnetic field of about 100 Oe nearly parallel to the c axis of the thin film. The observed wave form showed clear oscillations up to 80 K. The frequency was shifted from ϳ620 GHz at 24 K to ϳ300 GHz at 80 K, corresponding to an increase in c-axis penetration depth, c , from ϳ26 m to ϳ53 m, and disappeared above T C as expected for the Josephson plasma resonance.

Terahertz-pulse radiation phenomena of high-TC superconductors by ultrashort optical pulse illumination

“…Fig. 1a shows the typical time-domain waveforms of THz-pulses observed on YBa 2 Cu 3 O 7Àd (YBCO), Tl 2 Ba 2 CaCu 2 O 8+d (TBCCO), and Bi 2 Sr 2 CaCu 2 O 8+d (BSCCO) [2][3][4], and Fig. 1b shows the Fourier spectra of those THz-pulses.…”

“…On the other hand, we have researched the THz-pulse radiation phenomena of high-T C superconductors (HTSs) by FOP excitation [2][3][4]. In this research, the THz-pulses can be radiated from HTS samples applied with bias currents, by utilizing the ultrafast modulation of supercurrent, according to the following equation:…”

Terahertz Josephson plasma waves in layered superconductors: spectrum, generation, nonlinear and quantum phenomena

“…In such artificial systems, the coupling can be controlled by varying the thickness of the superconducting layers, thus resulting in a controllable change of the frequency (usually up to 0.7 THz) of the propagating electromagnetic waves. A great challenge is to excite electromagnetic waves in Bi 2 Sr 2 CaCu 2 O 8+δ samples in a controllable manner because of its sub-terahertz and terahertz frequency ranges [16,17], which is still hardly reachable for both electronic and optical devices. The poorly controlled THz range of electromagnetic spectra sits between 300 GHz and 30 THz which corresponds to 1000-10 µm (wavelength), 1.25-125 meV (energy) or 14-1400 K (temperature).…”

Nonlinear Wood anomalies in the reflectivity of layered superconductors

“…So, the layered structure of superconductors favors propagation of the electromagnetic waves through the layers. The great challenge is to excite the electromagnetic waves in layered superconductors in a controllable manner because of their THz frequency range [9,10] which is still hardly reachable for both electronic and optical devices.…”