3RD-ORDER NONLINEAR-OPTICAL SUSCEPTIBILITIES OF CDIN2O4 THIN-FILMS

Third-order non-linear optical susceptibilities, chi((3))(- 3 omega; o mega, omega, omega), for spinel-type oxide thin films prepared by rf m agnetron sputtering were evaluated using the third-harmonic generation method in the off-resonant region. The chi((3))(- 3 omega; omega, ome ga, omega) of MgAl2O4 was about 1.0 x 10(-12) esu and that of CdIn2O4 ranged from 1.8 to 4.5 x 10(-12) esu, which seemed to be relatively la rge compared with other inorganic materials. The origin of the large c hi((3))(- 3 omega; omega, omega, omega) was the spinel-type structure (AB(2)O(4)). Since octahedra with the B-site element in the center are linked by sharing an edge in space, it was expected that the delocali zation of the s-orbital of the B-site metal would be large. The reason why the chi((3))(- 3 omega; omega, omega, omega) of CdIn2O4 was sever al times larger than that of MgAl2O4 was that the optical band gap of CdIn2O4 was smaller than that of MgAl2O4.