  We present and analyze a novel concept for blue-detuned evanescent field
surface traps for cold neutral atoms based on two-mode interference in
ultra-thin optical fibres. When two or more transverse modes with the same
frequency co-propagate in the fibre, their different phase velocities cause a
stationary interference pattern to establish. Intensity minima of the
evanescent field at any distance from the fibre surface can be created and an
array of optical microtraps can thus be obtained in the evanescent field. We
discuss three possible combinations of the lowest order modes, yielding traps
at one to two hundred nanometres from the fibre surface which, using a few ten
milliwatts of trapping laser power, have a depth on the order of 1 mK for
caesium atoms and a trapping lifetime exceeding 100 seconds. The resulting
trapping geometry is of particular interest because atoms in such microtrap
arrays will be coupled to any additional field propagating in the fibre via the
evanescent field, thereby realising ensembles of fibre-coupled atoms.
