  We propose and demonstrate a scheme for strongly radially confining a single
neutral atom in a bichromatic far-off resonance optical dipole trap(BFORT) .
BFORT is composed of a blue-detuned Laguerre-Gaussian $LG^1_ 0$ beam and a
red-detuned Gaussian beam. The trapping radial dimension of a single atom
trapped in the Gaussian FORT can be greatly compressed by imposing a
blue-detuned Laguerre-Gaussian $LG^1_ 0$ beam with moderate potential depth. By
modulating the potential depth of the Gaussian FORT we observed that the
resonant and parametric excitation of the oscillatory motion of a single atom
in this BFORT and obtained the oscillation frequency that well fits prediction
from the theoretical model. The frequency measurement shows that effective
trapping dimension can be greatly sharper than that diffraction limited of
microscopic objective we used. Then we show that the excess scattering rate due
to imposing blue detuned light can be eliminated when single atoms is close to
ground-state theoretically. So BFORT suits the purpose of acting as a
Lamb-Dicke trap for further cooling a single neutral atom to motion
ground-state and finding application in quantum information progressing.
