solved with h5py read :
import h5py
with h5py.File(fname,'r') as hdf:
FieldGroups=hdf['FieldGroups']
keygroup = list(FieldGroups.keys())
valField = FieldGroups[keygroup[0]]
AllFields = valField['AllFields']
EMPotential = AllFields['EM Potential(x,y,z,f0)']
EMPotentialObject = EMPotential['_Object']
AdditionalFieldDataCollection =
EMPotentialObject['AdditionalFieldDataCollection']
Snapshots = EMPotentialObject['Snapshots']
Potential = Snapshots['0']['comp0']
#(n, m, k, 2) numpy array
PotentialData = Potential[()]
==========
this can be plotted
import pyvista as pv