Large nonlinear refraction and two photon absorption in ferroelectric Bi2VO5.5 thin films

Ferroelectric c-oriented Bi2VO5.5 (BVO) thin films (thickness ≈300 nm) were fabricated by pulsed laser deposition on corning glass substrates. Nonlinear refractive index (n2) and two photon absorption coefficient (β) were measured by Z-scan technique at 532 nm wavelength delivering pulses with 10 ns duration. Relatively large values of n2 = 2.05 ± 0.2 × 10−10 cm2/W and β = 9.36 ± 0.3 cm/MW were obtained for BVO thin films. Origin of the large optical nonlinearities in BVO thin films was discussed based on bond–orbital theory of transition metal oxides.

► Properties reported for the first time. ► Large nonlinear optical behaviour. ► Its origin has been discussed.