  We demonstrate laser interferometry based on phase difference between the two
arms of the interferometer. The experiments are done with a Cs atomic vapor
cell at room temperature and use atomic coherence. The interference can be
tuned from constructive to destructive by tuning the relative phase between the
two arms. It is similar to the Michelson interferometer, but differs in the
important aspect of allowing interference when the polarizations in the two
arms are orthogonal. This would be a novel method for interfering two
independent lasers, which even can allow interfering two independent lasers of
completely different wavelengths---such as of UV and IR---and also possibly
phase lock them.
