CSpace(DimensionString)
  DimensionString can be: 'T', 'X', 'R', 'TX', 'TR', 'XY', 'TXY':
  'T' - 1D time (fibers)
  'TX' - 2D time and cartesian X crossection (not yet
  understood by the author, possibly diffraction ni y direction
  is not present but walk-off in birefringent media should be
  ok)
  'TXY' - full 3D time and two cartesian coordinates
  (birefringent media, beams propagating at various directions)
  'X' - 1D crossection (CW laser diffraction + nonlinearity)
  'XY' - 2D for CW beams
  'TR' - 2D radial symmetry, no tilting and off axis
  propagation, non birefringent media (or propagation along the
  optical axis)
  'R' - 1D for CW beams