Nanosecond Optical Rectification and Photon Drag Effect in Nanocarbon Thin Films and Wires

Abstract

Intense laser pulses can produce quasi-static electric fields, due to photon drag and optical rectification effects, which manifest themselves as a dc current due to the transfer of the photon momentum to free carriers, and a dc polarization, respectively. In isotropic media, these nonlinear optical phenomena result in the generation of a current density. We report a theory of the dc response of the two-dimensional (nanographite film) and one-dimensional (carbone nanotube yarns) nanocarbon materials irradiated by nanosecond laser pulses. We interpret results of recent experiments and demonstrate that photon drag dominates the dc response in these nanocarbon materials. A voltage appeared across the irradiated nanocarbon samples, proportional to the power of the light beam. We find the equation describing the potential of the quasi-static electric field in the film. The light-induced charge separation gives a dipole-like nature to the electric field. In both one- and two-domensional nanocarbon materials, the temporal profile of the generated electric signal nearly coincides with the shape of the incident light pulse. This indicates that photon drag dominates the dc response. Our numerical simulation shows that nanographite film converts light with wavelength 1 μm, with efficiency 6 x 10 -3 A/W at optimal angle of incidence, i.e., it is about one to two orders larger than conventionally used bulk semiconductors (Ge, Te) and metals (Bi, Nb). In conclusion, we developed a theory of dc response of the one- and two-dimensional nanocarbon materials under irradiation with nanosecond light pulses. The demonstrated strong photon drag effect makes nanographite films and carbon nanotube yarns usable for captors in optoelectronics circuits.