Semimetallization of dielectrics in strong optical fields

Abstract

At the heart of ever growing demands for faster signal processing is ultrafast charge transport and control by electromagnetic fields in semiconductors. Intense optical fields have opened fascinating avenues for new phenomena and applications in solids. Because the period of optical fields is on the order of a femtosecond, the current switching and its control by an optical field may pave a way to petahertz optoelectronic devices. Lately, a reversible semimetallization in fused silica on a femtosecond time scale by using a few-cycle strong field (~1 V/Å) is manifested. The strong Wannier-Stark localization and Zener-type tunneling were expected to drive this ultrafast semimetallization. Wider spread of this technology demands better understanding of whether the strong field behavior is universally similar for different dielectrics. Here we employ a carrier-envelope-phase stabilized, few-cycle strong optical field to drive the semimetallization in sapphire, calcium fluoride and quartz and to compare this phenomenon and show its remarkable similarity between them. The similarity in response of these materials, despite the distinguishable differences in their physical properties, suggests the universality of the physical picture explained by the localization of Wannier-Stark states. Our results may blaze a trail to PHz-rate optoelectronics.

Few-cycle lightwave-driven currents in a semiconductor at high repetition rate

“…The extracted pulse profile and intensity spectrum can be seen in Fig. 2d and e. The FWHM duration of the retrieved pulse shape is equal to 6.4 fs, which corresponds to approximately 2.4 cycles at the center wavelength (787 nm)about twice as long as what has been used so far [11][12][13][14].…”

“…Lightwave-driven currents were investigated in several material systems, for example SiO2 [11], CaF2 [12], Al2O3 [13], and GaN [14]. In this context, gallium nitride (GaN) is particularly interesting as it is the commercial backbone of white light LEDs and power electronics, for example.…”

Perspective on Petahertz Electronics and Attosecond Nanoscopy

“…The studies of petahertz electronics and related devices are still in an early phase. Light-driven electronic devices fabricated from dielectrics materials, such as fused silica (SiO 2 ) [25], quartz, sapphire [110], calcium fluoride (CaF 2 ) [111], and wide-bandgap semiconductors, such as gallium nitride (GaN) [28], exhibit CEP-dependent photocurrent induced by few-cycle laser pulses. As one of the appli-cations, a solid-state light phase detector that is able to measure the absolute CEP of few-cycle laser fields has been demonstrated [27].…”

Interaction of crystalline topological insulator with an ultrashort laser pulse

“…The electric field in such pulses is comparable to the internal fields acting on electrons in solids. Such a strong electric field results in highly nonlinear interband and intaband electron dynamics, strongly modifying both transport and optical properties of solids during the pulse 14,15,20 . An important characteristic of such electron dynamics is its reversibility, i.e., electron system is highly perturbed during the pulse but returns to its initial state after the pulse.…”

“…The degree of reversibility (adiabaticity) of the electron dynamics depends on the energy dispersion, especially the band gap, and interband dipole matrix elements, which determine the strength of the interband coupling in the pulse field. It has been shown both experimentally and theoretically 15,16,20 , that for dielectrics (fused silica, quartz, and sapphire) the electron dynamics is highly reversible, which is due to large band gap (∼ 10 eV) of such materials and smooth dependence of the interband coupling on the wave vector. The reversibility of electron dynamics in dielectrics can be understood in terms of the dynamics of passage of anticrossing points of Wannier-Stark states belonging to different bands 15,16 .…”