How can I set input power (in absolute unit say 100 mW or so) while running a FDTD/ FDE/EME solver?

dipanpaldipanpal Member Posts: 1
edited August 17 in Photonics

I do understand that these solvers allow to specify the input power by varying the input source amplitude in the input source settings or while injecting a mode using ports. However my work needs me to input absolute value of power in standard units, say in mW/uW from various source (mainly gaussian beam and mode sources in ports), and also measure the output power either from monitors or advanced analysis group in similar units. Please help!

Best Answer

  • gsungsun Posts: 954Ansys Employee
    Accepted Answer

    I think you can first get the source power by either integrating the Poyinting vector of the source or use sourcepower script( see sourcepower - Script command ), then normalize the source amplitude to the desired power. For example, the original source power is SW, and the desired power DSW, then the source amplitude can be modified to be


    Once you do this, you can also recalculate the source power to verify this.


  • dipanpaldipanpal Posts: 2Member


    Thanks for your reply. That was helpful!

    I am trying to simulate the power transmitted through a Silicon rectangular waveguide (WG) structure to be used in a hybrid Electronic-Photonic IC for some time now.

    However, I am having some issues: The structure is a long waveguide (say around 100um or even longer), but in the simulation I am using only 10um length. I am injecting light (either considering exciting the WG with a particular mode or using a gaussian beam which represents a Laser source) along the WG length, i.e. in the X direction, and the YZ cross section of the WG is a 200nm x 200nm square.

    I need radiation/optical power to come out from the WG through several square openings in the XY plane (such that the radiation comes out along the Z- direction) to illuminate some other devices. However, the transmission (T) as measured from the power monitor, is extremely low, and cannot be used to illuminate other structures.

    At present I am using a wavelength of 1.55um, however I'll need to simulate the same thing using 532 nm, which will make the transmittance even worse.

    It will be of much help if you could please let me know what is the issue with the simulation to cause such low transmission of optical power!

    I tried attaching the FDTD simulation file, but that file format is not supported for attachment!

    Please let me know how to send you the simulation file.

  • gsungsun Posts: 954Ansys Employee

    This is different from this topic, please write a separate post. Thank you!

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