Holographic interferometry of liquids at the He-Ne laser wavelength under microwave irradiation

Changes in the optical refractive indices of a number of organic liquids, water, and some biological aqueous solutions exposed to (37.5–78)-GHz electromagnetic radiation have been investigated using a differential holographic interferometer. It is established that irradiation with intensities up to 10 mW/cm2 may reduce the refractive index of liquids by ∼10−3 as a result of thermal changes in the dielectric constant of the material studied. The magnitude and dynamics of changes in the refractive index are determined by the irradiation intensity and physical parameters of liquids (dipole moment of molecules, absorption coefficient, permittivity, and temperature coefficient of the refractive index) and are independent (within the experimental error) of the mutual orientation of the polarization unit vectors of the microwave and optical fields.