  Femtosecond laser exposure in the non-ablative regime induces a variety of
bulk structural modifications, in which anisotropy may depend on the
polarization of the writing beam. In this work, we investigate the correlation
between polarization state and stress anisotropy. In particular, we introduce a
methodology that allows for rapid analysis and visualization of laser-induced
stress anisotropy in glasses and crystals. Using radial and azimuthal
polarization, we also demonstrate stress states that are nearly isotropic.
