Photoinduced optical and second-order non-linear optical effects in nanolayers separating indium oxide (In2O3) Crystalline films doped by Al, Sn, and glass substrates were found. Photoinduced optical second harmonic generation was applied as a particular non-linear optical method. The photoinduced second-order non-linear susceptibilities (at lambda = 1.76 mum) show good correlation with the photoinduced linear optical susceptibilities, particularly with the optical absorption. The performed experimental measurements show that the observed effects are caused by two factors. The first one is related with the potential gradient on the glass-In2O3 film border. The second one is caused by additional polarization due to doping by the Al and Sn atoms. Such near-the-border nanolayers can be considered as new type of second-order optical materials. (C) 2003 Elsevier B.V. All rights reserved.