Документ взят из кэша поисковой машины. Адрес оригинального документа : http://nanolab.phys.msu.ru/sites/default/files/afinogenov_pp.pdf Дата изменения: Unknown Дата индексирования: Sat Apr 9 23:04:13 2016 Кодировка:

DAYS on DIFFRACTION 2015

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Femtosecond sp ectroscopy of the electron thermalization in gold in the vicinity of Tamm plasmon resonance
Afinogenov B. I., Bessonov V. O., Fedyanin A. A. Faculty of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia e-mail: fedyanin@nanolab.phys.msu.ru Tamm plasmon-polaritons (TPPs) have attracted huge interest since their first experimental observation in 2008. TPPs are surface states which arise at the boundary of 1D photonic crystal and metal film [1]. They are greatly analogous to the well-known surface electromagnetic waves and surface plasmon-polaritons, yet have distinctive features. TPPs exist for both s and p polarizations of the incoming light and do not require satisfaction of in-plane phase-matching conditions, thus they can be excited at any angle of incidence. Experimentally, TPP can be detected as a narrow absorption resonance in reflectance spectrum of a PC/metal structure. Electromagnetic field localization [2, 3] in the TPP mode leads to the enhancement of the nonlinear-optical phenomena, as it was demonstrated recently [4, 5]. Studied sample of one-dimensional PC consists of 6 pairs of ZrO2 /SiO2 layers (average thicknesses 110 nm and 145 nm, respectively) covered with a semitransparent 30-nm-thick gold film. Measurements of the reflectivity change were performed in a conventional cross-polarized pump-probe scheme with a Ti:Sa laser as a source of radiation (fig.1a). Pump pulses had an energy of 60 pJ, while probe pulses were approximately 25 times weaker. Pump and probe beams were independently focused into the 40-µm wide spots on the sample. Wavelength was tuned in the range of 700­820 nm. Figure 1b shows measurements of the time-dependent change in reflectivity of the Au/PC sample. Before the pump pulse have illuminated the sample (time less than zero) no change in reflectivity was observed. When probe pulse reflected from them pump-illuminated sample, the change in reflectivity appeared, reaching its maximum at approximately 250 fs after the zero time, and decaying for approximately 4 ps (not shown). Arrow indicate point where data was acquired for a spectroscopic measurements. Figure 1b shows reflectance spectrum of the Au/PC sample with a solid line. A TPP-associated resonance is observed with a minimum at 765 nm. Spectrum of the relative change in reflectivity R/R is shown with black dots. It exhibits a derivative-like shape in the vicinity of the TPP resonance. Maximal absolute values of the R/R are observed at 760 and 770 nm at the falling and rising edges of the TPP resonance respectively. Corresponding values of the reflectivity change are in the order of 3·10-3 , which is approximately 10 times larger than the previously reported R/R values for a bare gold film [6].

Fig. 1: (Color online) (a) Sketch of the experiment. (b) Transient reflectivity measured in the Au/PC sample at 760 nm. (c) Dots -- experimental spectrum of the relative change in reflectivity of the Au/PC sample. Solid red curve -- experimental reflectance spectrum of the Au/PC sample.

References [1] J. A. Gaspar-Armenta and F. Villa, J. Opt. Soc. Am. B 20, 2349 (2003).


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[2] M. Kaliteevski, I. Iorsh, S. Brand et al., Phys. Rev. B 76, 165415 (2007). [3] M.E. Sasin, R.P. Seisyan, M.A. Kaliteevski et al., Appl. Phys. Lett. 92, 251112 (2008). [4] B.I Afinogenov, V.O. Bessonov, and A.A. Fedyanin, Opt. Lett. 39, 6895 (2014). [5] H. Jiang, H. Chen, Y. Li et al., AIP Adv. 2, 041412 (2012). [6] C.-K. Sun, F. Vallґ L. Acioli et al., Phys. Rev. B 48, 12365(R) (1993). ee,