A reviewer mentioned that: ". For such class of the glasses (tungsten-phosphate glass) principal role begin to play the space charge density distribution. Please evaluate its space distribution."
What was the topic of you paper? Did you study AC or DC dielectric properties? Under which conditions? Space charge distribution can be investigated if you apply a strong DC field and then cool down the sample. Space charge distribution in polymer insulators is usually studied by piezoeletcric pulse techniques, but it requires a special setup.
Thank you Gyorgy. Indeed the reviewer asked us something out of scope. We just reported the optical properties of these glasses under room temperature and without any applied magnetic or electric fields.