Theoretical Study Of Novel Atom-optical Mirrors

Due to the ac Stark effect, neutral atoms will undergo a dipole force from the inhomogeneous electromagnetic fields, while the dipole force acting on the atoms is proportional to the atomic dipole momentum and the gradient of light field. When the laser frequency is larger than the atomic resonance frequency (blue detuning), the atoms will experience a repulsing force that will repulse the atoms to the minimum place of light field. This is the principle of atomic mirror or atomic guide and trap.In this thesis, we propose three novel mirrors to reflect atoms by using intensity gradient induced by a blue-detuned semi-Gaussian laser beam, a blue-detuned semi-ellipse-Gaussian laser beam and a blue-detuned semi-flattened-Gaussian laser beam.First, we propose a novel and simple mirror to reflect atoms by using intensity gradient induced by a blue-detuned semi-Gaussian laser beam. The diffraction characteristics of an incident Gaussian beam by straight edge bounding a semi-infinite opaque plate are investigated from Kirchhoff scakr wave theory in the Fresnel limit. Our study shows that the optical potential of the diffracted light of the semi-Gaussian beam is far higher than that of the evanescent-light wave, and its maximum normal velocity of the incident atoms can be far grater than that of the evanescent-light wave under the same parameters, so the blue-detuned semi-Gaussian beam, as a novel atomic mirror, can be used to efficiently reflect atoms with a normal velocity of greater than 1 m/s. However, the intensity gradient (force) of the diffracted light of the semi-Gaussian beam is far smaller than that of the evanescent-light wave, so its spontaneous emission probability is greater than that from the evanescent-light one when the normal velocity of the incident atom is greater.Second, we propose the second mirror scheme to reflect atomic by using a blue-detuned semi-ellipse-Gaussian beam (SEGB). When the beam waist along the y direction of blue-detuned SEGB is the same as that of the SGB, due to a smaller crosssurface, the absolute intensity distribution of the blue-detuned SEGB is larger than that of the SGB with the same incident laser power. When the beam waist wy of blue-detuned SEGB along the y direction is 10 mm, and its wx is decreased from 10 mm to 1mm, the absolute diffracted intensity from the SEGB surface will be 10 times of that from the SGB surface, which can be used to reflect an incident atomic beam with a higher normal velocity.Finally, we propose the third mirror scheme to reflect atomic by using a blue-detuned semi-flattened-Gaussian beam (SFGB). Under the same beam parameters, the intensity gradient near the mirror surface of the blue-detune SFGB is the nearly same as that of the SGB, but the intensity distribution of the FGB is a constant within a larger radial range, the width of the SFGB mirror will far greater than one of the SGB mirror. For example, when the beam waists of both GB and FGB are equal to 10 mm, the width of the SFGB mirror is -3.6 times of the SGB one.