An Investigation of the Movable Dipole Trap produced by Liquid Lenses

Abstract

In this thesis, the theory of a movable optical dipole trap produced by liquid lenses is developed, and the relevant electronic devices for focus tuning and temperature stabilization are also demonstrated. The theory focuses on the atom- eld interaction and light-lens relation. For the atom- eld interaction, the linear relation between the light intensity and the trap potential is derived with the eld quantization method, and nding the trap potential becomes the problem of nding the intensity distribution. For the light-lens relation, the theory of the surface pro le of the liquid lens is developed. It shows that the optical power 1=f of the lens is proportional to the pressure in the lens. It is also found that the intensity of light at the focal point is proportional to the square of the optical power under the paraxial approximation. A special lens combination is analyzed, and the characteristic curves are computed according to Gaussian optics. The di culty of non-paraxial free space propagation is addressed by integrating the tomographic method, so the rotational symmetry is fully exploited to calculate the intensity distribution at the focal point. The aberration at the focal point is analyzed by geometric ray tracing. Transistors are used to tackle the di culty of a low output current of the operational ampli er, which allows the electronic devices that control the current to the lens and stabilize the temperature of the lens to be possible. In addition, a cloud temperature measurement of the magneto-optical trap is carried out in conjunction with the theoretical evaluation to determine the laser power. The thesis nishes with some notes for future experiments with the liquid lens system for the realization of an optical dipole trap.