LASER-INDUCED LIGHT-FORCE INTERACTION IN THE OPTICAL NEAR-FIELD REGION

Laser light can induce many effects on the vicinity of the sample surf ace due to the proximity effects, such as the field enhancement at the surface of a small conducting particle; plasma exchange effect betwee n the metallic tip and substrate surface. We have observed a new optic al tip-sample interaction: laser induced force as the results of light pressure in the near-field region. Under the side illumination of a l aser light, an additional attractive force was observed between a diel ectric tip and various samples of C-60, optical glass, YBa2Cu3O7-d (YB CO) thin film. No such effect was observed in metallic samples. This o ptical binding force is due to the multiple scattering of light betwee n two close objects. The results are in good agreement with the recent theoretical calculation. The effects of the optical refraction index, thermal expansion of probe tip due to laser radiation are discussed.