If you are modelling illuminating effect, most likely you will model the system under non-sequential mode and you could look up vFE;D@bz:
_@
*+~9%8p
Source Diode and Source Gaussian 2WtRJi?b|
uHAT#\m:
to check if these two sources types support your source behavior. If they do then it should serve an good approximation for your light source.