Optical dipole trap inside a laser resonator.

Abstract

We report the first realization, to our knowledge, of an optical dipole trap inside the active resonator of a laser. The concept, which is demonstrated with a CO2 laser (lambda = 10.6 microm), combines the advantages of optical power enhancement (up to 1.3-kW peak power) with the intrinsic stability of laser intensity as a result of the feedback of the active laser medium. Two kinds of trapping geometries are presented: a Gaussian trap in a transverse TEM00 mode and a boxlike transverse confinement in a superposition of transverse modes. In addition, longitudinal superlattices are created by two-frequency operation of the laser. Transfer efficiencies of up to 50% from a cesium magneto-optical trap are achieved. Storage times (7 = 0.3 s) are mainly limited by the background gas pressure. Possible sources of additional loss of atoms are discussed.