What light source I can use to couple light to thin film in free space

- March 6, 2024 at 7:17 pm
  
  Chuan Zhong
  Subscriber
  
  Hi,
  Can anyone give me some recommendation about what type of source I should use in a free space?
  I am buidling a simaple model to calculate the reflection when light path two flilms.
  I only would like get the refection at a small region of the film so the input source needs to be as small as passible, is it there any phycial limitition for the size of a mode source, for example, if the input wavelength is 580nm, can I make a mode source size with 290nm? or do I consider a different source, Thank you.
  
  Best wishes
  Chuan
- March 8, 2024 at 12:56 am
  
  Amrita Pati
  Ansys Employee
  
  Hi Chuan,
  I would not recommend using a mode source. The mode source is used to inject guided waveguide modes into a geometry, here you are simulating free-space propagation. Usually we would use a plane wave/Gaussian source for free space propgation. Would you be able to share a few more details like: What kind of BCs are you using? Does the simulation have a specific width in the horizontal direction? Also, I think even if you use a larger source, you should be able to see the transmission through the smaller region if you just use a small monitor. But if you could provide the above details, I can share more specific recommendations.
  Regards,
  Amrita