Wavelength modulated excitonic spectra of Cu2O thin films sandwiched by MgO plates Kazunori Iwamitsu, Shingo Aihara, Tomoshige Shimamoto, Atsuhiro Fujii and Ichiro Akai Eur. Phys. J. B, 86 5 (2013) 194 Published online: 29 April 2013 DOI: 10.1140/epjb/e2013-30595-4