Anisotropic Terahertz Emission from Bi2Se3 Thin Films with Inclined Crystal Planes

Anisotropic Terahertz Emission from Bi2Se3 Thin Films with Inclined Crystal Planes

We investigate the surface states of topological insulator (TI) Bi2Se3 thin films grown on Si nanocrystals and Al2O3 substrates by using terahertz (THz) emission spectroscopy. Compared to bulk crystalline Bi2Te2Se, film TIs exhibit distinct behaviors in the phase and amplitude of emitted THz radiation. In particular, Bi2Se3 grown on Al2O3 shows an anisotropic response with a strong modulation o...

Resonant terahertz generation from InN thin films.

Highly efficient conversion from ultrafast optical pulses to their terahertz (THz) counterparts has been achieved with InN thin films. An average THz output power as high as 0.931 microW has been obtained for an average pump power of 1 W, corresponding to a normalized conversion efficiency of 190% mm(-2). Based on our measured dependences of the THz output power on pump polarization, incident a...

Terahertz emission from YBa2Cu3O7Àd thin films via bulk electric-quadrupole–magnetic-dipole optical rectification

We report the observation of terahertz emission from YBa2Cu3O72d thin films excited by 1.5-eV, 150-fs pulses in the absence of external electric or magnetic fields. This emission is characterized for optimally doped d50 films and underdoped d50.5 films, over a range of temperatures T, 4 K,T,300 K, where the films change from superconductors to correlated metals. It exhibits a pronounced 4f depe...

Narrow-band tunable terahertz emission from ferrimagnetic Mn3-xGa thin films

Effect of Surface States on Terahertz Emission from the Bi2Se3 Surface

Three-dimensional topological insulators are materials that behave as an insulator in the interior, but as a metal on the surface with Dirac surface states protected by the topological properties of the bulk wavefunctions. The newly discovered second surface state, located about 1.5 eV above the conduction band in Bi2Se3 allows direct photoexcitation of the surface electrons in n-doped samples ...