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Effect of Photon Lifetime in Silicon Nanowire Ensembles on Efficiency of Raman Scattering and Third-Harmonic Generationтезисы доклада
- Авторы: Golovan L.A., Zabotnov S.V., Tkachenko N.B., Presnov D.E., Osminkina L.A., Efimova A.I.
- Сборник: The 25th International Conference on Advanced Laser Technologies [ALT'17], Book of abstracts
- Тезисы
- Год издания: 2017
- Место издания: Electronics and Telecommunications Research Institute Busan, Korea
- Первая страница: FC-II-3
- Аннотация: Ensembles of silicon nanowires (SiNWs) of about 100 nm in diameter are of great interest. Typically, SiNWs are aligned pillars with the length controlled by the formation procedure. They are characterized by extremely low reflection and high light absorption in the visible spectral region and high reflection in near-infrared (NIR) region indicating their promising photovoltaic or sensor applications. Enhanced efficiency of such optical processes as Raman scattering, third-harmonic (TH) generation, and photoluminescence are found in SiNWs. These effects are often connected with the light trapping in SiNW arrays caused by effective light scattering, which in its turn depends on length, orientation, and arrangement of the SiNWs. Thus, studying correlation of the SiNW structural parameters and efficiency of the optical processes including nonlinear-optical ones seems to be very instructive for further applications of the SiNW arrays. To reveal effects of SiNW ensemble structure on efficiency of the optical processes the dependence of the Raman scattering and TH signals on the light polarization and thickness of the sample were found. These processes are sensitive to the light polarization and local field effects. The obtained results were complemented by measurements of cross-correlation function for the laser pulse and radiation scattered by SiNW ensemble, which allows estimation of photon lifetime in SiNW. A quasi-cw Cr:forsterite laser radiation (1250 nm, 80 fs, 150 mW, 80 MHz) was used for these purposes. Dependences of Raman and TH signals on the thickness of SiNW layer demonstrate rise increase with the layer thickness increase. For the TH signal the rise follows a decrease in the TH intensity for thinner layers, while Raman signal grows monotonously from the thinnest SiNW layers and tends to saturation. The photon lifetime revealed function has an expressed tail, indicating diffusion-like radiative transport in the SiNW array. The rise of the TH generation efficiency starts at the same thickness as the increase of the photon lifetime in the SiWNs. Such a correlation let us suppose that the latter one is responsible for the rise of the TH generation efficiency. The SiNWs formed on (110) Si substrate are tilted at 45° to the surface. In this case, TH signal exceeds one for crystalline Si, in the case of the fundamental radiation incident perpendicular to the SiNWs, whereas in the case of incident wave propagation along the SiNWs it falls several time in comparison with crystalline Si,. Thus, multiple scattering of near-infrared light in SiNW ensembles leads to photon lifetime enhancement which is manifested by substantial increase of the Raman scattering and TH generation efficiencies. Polarization dependence of the TH signals strongly depends on the incident wave propagation (perpendicular or parallel to the SINW), with the light incidence perpendicular to the SiNWs being more effective than along the SiNWs. The obtained results could be explained by variations of in the local fields in SiNWs and scattering cross-section. The work was supported by the Russian Foundation for Basic Research Grant no. 15-29-01185, and it was partially performed at the Center of User’s Facilities of Moscow State University.
- Добавил в систему: Головань Леонид Анатольевич