What does the FluxMonitor record?

Date	Category
2025-09-08 17:29:25	Monitors

The FluxMonitor records field data tangential \(E\) and \(H\) fields colocated to the cell boundaries in the monitor’s 2D plane grid. It then computes and integrates the Poynting vector, returning the real part of this integral as the flux.

Real$(\sum\limits_{\text{cells in monitor}}\frac{1}{2}(E_1\cdot H_2^*-E_2\cdot H_1^*)dA_{\text{cell}})$
where $dA$ is the area of each cell in the monitor, and the field components 1 and 2 are given depending on the monitor geometry: for $x$-normal monitors, 1 is $y$ and 2 is $z$; for $y$-normal monitors, 1 is $x$ and 2 is $z$; for $z$-normal monitors, 1 is $x$ and 2 is $y$. See the code [here](https://docs.flexcompute.com/projects/tidy3d/en/latest/_modules/tidy3d/components/data/monitor_data.html#ElectromagneticFieldData).