  We study the wave optics features of gravitational microlensing by a binary
lens composed of a planet and a parent star. In this system, the source star
near the caustic line produces a pair of images in which they can play the role
of secondary sources for the observer. This optical system is similar to the
Young double-slit experiment. The coherent wave fronts from a source on the
lens plane can form diffraction pattern on the observer plane. This diffraction
pattern has two modes from the close- and wide-pair images. From the
observational point of view, we study the possibility of detecting this effect
through the Square Kilometer Array (SKA) project in the resonance and high
magnification channels of binary lensing. While the red giant sources do not
seem satisfy the spatial coherency condition, during the caustic crossing, a
small part of source traversing the caustic line can produce coherent pair
images. Observations of wave optics effect in the longer wavelengths
accompanied by optical observations of a microlensing event provide extra
information from the parameter space of the planet. These observations can
provide a new basis for study of exoplanets.

Earth and Planetary Astrophysics;General Relativity and Quantum Cosmology