Learning Forum

[klsh6568]

Hello,

I have a question regarding the scale factor in the Import Heat tab and the source power scaling in the Transient tab of Lumerical HEAT.

From the photothermal example, I understand that the scale factor is defined as the power (in watts) applied to the simulation region. However, I could not find clear documentation explaining how to input the desired peak power for transient simulations.

For instance, if light with a power of 1 W is applied with a 10 kHz repetition rate and a 10 ns pulse width, the peak power can be calculated as 10 kW. If I want to simulate this case (to calculate the temperature field during the pulse duration of 10 ns), how should I set the scale factor and the source power scaling?

Additionally, could you clarify the exact definition of source power scaling? While I found a brief description on the website, it seemed insufficient to fully understand its functionality.

Thank you!

[kghaffari]

Hi,

Thank you for posting your question. First, the 'source power scaling' specified in HEAT's transient tab works similarly to the 'scaling factor' in each individual heat source. The only difference is that the 'source power scaling' applies to all heat sources. I think keeping this value to 1 and making any needed changes in the 'scaling factor' can be helpful for avoiding making mistakes when setting up the simulation.

For choosing a scaling factor, I think the correct value depends on how you are trying to replicate the incident pulse. You may decide to apply HEAT's shutter functions to mimic the actual pulse. In that case, the imported data should correspond to the actual power of the incident light. In your example this will be 1W. If your optical simulation (e.g. in FDTD) is set up to inject 1W power, then the scaling factor will be 1. You need to make sure that the shutters are applied according to the actual pulse shape and repetition for accuacy. HEAT's shutter functions only include single steps and pulses at the moment, so for your example you would need many individual heat sources so you can apply 1 pulse shape to each. Alternatively, you may decide to model an equivalent function in HEAT in which case the scaling factor and number of pulses will be different (e.g. 1 pulse with higher scaling factor but only 1 repetition).

Best regards,

Khash