https://arxiv.org/ftp/arxiv/papers/1604/1604.03869.pdf
"Substituting Eq. (19) into Eq. (6) gives the photon radius ... (20) where re is the classical radius of an electron. Since the length of a photon is equal to half of the wavelength and the radius is proportional to square root of the wavelength, the size and shape of a photon vary with the photon energy or wavelength. A photon is in shape like a thin stick if its energy is lower than the rest energy of an electron and like a plate if its radius is smaller than the classical radius of an electron".
I would presume that for a circle or sphere, the "length" would just be the diameter and 2*radius. Yet here, it says length is proportional to half the wavelength, while radius is proportional at a square root level.
So how does "length" differ from radius here? I presume a photon here is being treated as some sort of wave packet of light quanta, but I don't know what dimensions of measurement "length" and "radius" are referring to. And what would be the third dimension of measurement, would it be equal to the length, or to the radius?