LP01-mode output beam from a micro-sized hollow optical fiber: A simple theoretical model and its applications in atom optics

We calculate electric field distributions of the output beam from a LP01 mo de in a micro-sized hollow optical fiber under the Fresnel approximation an d find that the output beam characteristics in free space is similar to tha t of a TEM01* doughnut laser beam. We propose a simple theoretical model, a modified TEM01* doughnut beam, to simulate the free-space output beam from the LP01 mode in hollow fibers, and discuss potential applications of the LP01-mode output beam in atomic guiding, funneling, cooling, and trapping. Our study shows that this model is in good agreement with the numerical res ults derived from the Fresnel diffraction theory (except near the weak firs t-order diffraction ring around the zero-order diffraction peak). The model can be conveniently used to calculate the optical potential, gradient forc e, light-induced acceleration, spontaneous-emission rate, and quantum tunne ling loss in atomic guiding, funneling, and trapping with the LP01-mode out put beam in free space. It can be also used to study the optical-potential evaporative cooling of cold atoms in a gravito-optical trap constructed by the LP01-mode output beam. (C) 1999 American Institute of Physics. [S0021-8 979(99)06204-0].