  We present a study on characteristics of a magneto-optical trap (MOT) as an
optical lattice. Fluorescence spectra of atoms trapped in a MOT with a
passively phase-stabilized beam configuration have been measured by means of
the photon-counting heterodyne spectroscopy. We observe a narrow Rayleigh peak
and well-resolved Raman sidebands in the fluorescence spectra which clearly
show that the MOT itself behaves as a three-dimensional optical lattice.
Optical-lattice-like properties of the phase-stabilized MOT such as vibrational
frequencies and lineshapes of Rayleigh peak and Raman sidebands are
investigated systematically for various trap conditions.
