docs: def change_wavelength(self, wavelength):
          '''
          Changes the wavelength of the structure.
  
          This will affect the mode solver and potentially
          the refractive indices used (provided functions
          were provided as refractive indices).
  
          Args:
              wavelength (float): The new wavelength.
          '''
          for axis in self.axes:
              if issubclass(type(axis), Slabs):
                  axis.change_wavelength(wavelength)
          self.xx, self.xy, self.yx, self.yy, self.zz = self.axes
          self._wl = wavelength