Large Third-order Optical Nonlinearity in SrBi_2Nb_2O_9 Thin Films Prepared by Pulsed Laser Deposition

摘要

Well-crystallized SrBi_2Nb_2O_9 (SBN) thin films with smooth surfaces (the root mean square roughness is about 4.550 nm over an area of 2×2 μm~2) are fabricated on MgO (100) substrates by the pulsed laser deposition technique at 750 °C under the oxygen pressure of 30 Pa. The nonlinear optical properties of the films are studied by using a single beam z-scan with ns pulses at 532 nm. SBN thin films exhibit an excellent nonlinear optical response, with the real and imaginary parts of the third-order nonlinear optical susceptibility being 4.139×10~(-7) esu and 1.104×10~(-7) esu, respectively. These show that SBN ferroelectrics thin films have potential applications in nonlinear optics.