  We analyze evanescent fields of laser written waveguides and show that they
can be used to trap atoms close to the surface of an integrated optical atom
chip. In contrast to subwavelength nanofibres it is generally not possible to
create a stable trapping potential using only the fundamental modes. This is
why we create a stable trapping potential by using two different laser colors,
such that the waveguide supports two modes for the blue detuned laser, while
for the red detuned light the waveguide has only a single mode. In particular,
we study such a two-color trap for Cesium atoms, and calculate both the
potential and losses for the set of parameters that are within experimental
reach. We also optimize system parameters in order to minimize trap losses due
to photon scattering and tunneling to the surface.
