Why "waveguide_length" in function "Grating coupler simulation" cannot correspond to FDTD parameters？

[Zwlzzm]

Hi,

I find changing parameter "waveguide_length" in Klayout cannot take effect in Lumerical FDTD.

For, "waveguide_length", it seems that it only for 3D simulation, However, no matter how to change the value of "waveguide_length". This parameter in FDTD (waveguide length) is always 10um.

  filename = matches[0]

  # set 2D GC geometry parameters
  lumapi.evalScript(_globals.FDTD,
  "load('%s'); select('grating_coupler_3D'); set('duty cycle',%s);\
  set('etch depth',%s); set('pitch',%s);\
  set('target length',%s); set('L extra',%s);\
  set('radius',%s); set('y span',%s);\
  set('waveguide width',%s); set('waveguide length,%s);'"
  % (filename, GC_settings['duty_cycle'], GC_settings['etch_depth'],
  GC_settings['pitch'],GC_settings['target_length'],GC_settings['length_extra'],
  GC_settings['radius'],GC_settings['y_span'],
     GC_settings['waveguide_width'],GC_settings['waveguide_length']))