Cryst. Res. Technol. 40, No. 3, 259 – 263 (2005) / DOI 10.1002/crat.200410335 © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Acoustically induced optical second harmonic generation in InAs crystals M. Makowska-Janusik 1 , A. Hruban 2 , J. Ebothe 3 , and I. V. Kityk* 1 1 Institute of Physics, J. Dlugosz Academy of Częstochowa, al. Armii Krajowej 13/15, Częstochowa, Poland 2 Institute of Electronic Matrials Technology, ul.Wolczanska 133, Warsaw, Poland 3 Universite de Reims, UFR Sciences, Unite de Thermique et d'Analyse, Physique-LMET UPRES EA N2061, Reims, France Received 18 February 2004, revised 11 March 2004, accepted 2 May 2004 Published online 1 February 2005 Key words InAs, second harmonic. PACS 42.70.Mp Acoustically induced optical second harmonic generation (AIOSHG) in InAs single crystals was investigated. With increasing acoustical power, the AIOSHG for fundamental CO laser light (λ=7.1 µm) increases and achieves its maximum value at acoustical power density about 1.70 W/cm 2 . The value of the AIOSHG for InAs was substantially higher than for key inorganic photo-refractive and ferroelectrics materials. With decreasing temperature, the AIOSHG signal strongly increases below 42 K. The AIOSHG maxima were observed at acoustical frequencies ranged at 7-11 kHz. Comparing the obtained results with the acoustically induced IR spectra at low temperature, one can conclude that the observed effect is associated with acoustically-induced phase transformations. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Since the discovering of the acoustically induced optical second harmonic generation (AIOSHG) by Nelson and Lax [1], AIOSHG has been revealed in several composites [2,3]. One of the physical origin of the AIOSHG is a spatial asymmetry of photocarrier excitation under external acoustical power [4]. In particular, it was shown that this asymmetry is prevailingly caused by interference of electron-hole and electron-phonon interactions. From general phenomenological considerations, one can guess that the crystalline IR-materials may be considered as promising materials for such kind of effects. Due to close values of the IR phonon modes and interacting laser frequencies one can expect an appearance of low-frequency quasi-phonon modes, or “soft” modes, which are directly related with anharmonic electron-phonon interactions [6,7]. In the present work, we explore single InAs single crystals. A particular attention is paid to their AIOSHG studied versus acoustical power, frequency and temperature. These materials could be of interest in IR technological devices and comparison with the AIOSHG for several other photorefractive ferroelectric crystals is given. 2 Experimental details The investigated InAs single crystals were cut along principal crystallographic axes and had the sizes 5 x 5 x 0.6 mm 3 . The schematic measurement set-up for the AIOSHG is shown in Fig. 1. As a source of optical second harmonic generation (fundamental laser beam), we used pulsed mode-locked CO laser supplied with an optical parametrical generator operating in 7.2-7.6 μm spectral range. The acoustical field was applied to the InAs ____________________ * Corresponding author: e-mail: i.kityk@ajd.czest.pl