Hi JAK; In string theory electrons, quarks, photons are all viewed as strings. I believe the wave packet of a photon is still part of the underlying theory of light;
In 1900,
Maxwell's theoretical model of light as oscillating
electric and
magnetic fields seemed complete. However, several observations could not be explained by any wave model of
electromagnetic radiation, leading to the idea that light-energy was packaged into
quanta described by E=hν. Later experiments showed that these light-quanta also carry momentum and, thus, can be considered
particles: the
photon concept was born, leading to a deeper understanding of the electric and magnetic fields themselves.
The
Maxwell wave theory.
The packet being from amplitude to amplitude. Notice it being a transverse wave it has 3D characteristics i.e. LWH. A sting can be as small as a 1 dimensional Planck length entity, to as large as a stretched out brane the size of our universe, according to some string theorist. Best to you, Pat