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Optical and Nonlinear Optical Response of Light Sensor Thin Films
Department of Physics, University of Puerto Rico, Mayaguez, PR00681, USA
F.Ioffe physical-Technical Institute, Russian Academy of Sciences, Saint-Petersburg 194021, Russia
Department of Physics, University of Puerto Rico, Rio Piedras, PR00931, USA
* Author to whom correspondence should be addressed.
Received: 22 May 2004; Accepted: 14 November 2004 / Published: 27 April 2005
Abstract: For potential ultrafast optical sensor application, both VO2 thin films andnanocomposite crystal-Si enriched SiO2 thin films grown on fused quartz substrates weresuccessfully prepared using pulsed laser deposition (PLD) and RF co-sputteringtechniques. In photoluminescence (PL) measurement c-Si/SiO2 film containsnanoparticles of crystal Si exhibits strong red emission with the band maximum rangingfrom 580 to 750 nm. With ultrashort pulsed laser excitation all films show extremelyintense and ultrafast nonlinear optical (NLO) response. The recorded holography fromall these thin films in a degenerate-four-wave-mixing configuration shows extremelylarge third-order response. For VO2 thin films, an optically induced semiconductor-tometalphase transition (PT) immediately occurred upon laser excitation. it accompanied.It turns out that the fast excited state dynamics was responsible to the induced PT. For c-Si/SiO2 film, its NLO response comes from the contribution of charge carriers created bylaser excitation in conduction band of the c-Si nanoparticles. It was verified byintroducing Eu3+ which is often used as a probe sensing the environment variations. Itturns out that the entire excited state dynamical process associated with the creation,movement and trapping of the charge carriers has a characteristic 500 ps duration.
Keywords: sensor; VO2; c-Si/SiO2; ultrafast; optical response.
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Liu, H.; Rua, A.J.; Vasquez, O.; Vikhnin, V.S.; Fernandez, L.F.; Fonseca, F.; Resto, O.; Weisz, S.Z. Optical and Nonlinear Optical Response of Light Sensor Thin Films. Sensors 2005, 5, 185-198.
Liu H, Rua AJ, Vasquez O, Vikhnin VS, Fernandez LF, Fonseca F, Resto O, Weisz SZ. Optical and Nonlinear Optical Response of Light Sensor Thin Films. Sensors. 2005; 5(4):185-198.
Liu, H.; Rua, A. J.; Vasquez, O.; Vikhnin, V. S.; Fernandez, L. F.; Fonseca, F.; Resto, O.; Weisz, S. Z. 2005. "Optical and Nonlinear Optical Response of Light Sensor Thin Films." Sensors 5, no. 4: 185-198.