Fano Resonance: Bright-Dark Mode Phase Portrait

This is the 2D counterpart to the 3D plasmonic dolmen-nanoantenna simulator, computed independently from the same driven coupled-oscillator physics rather than a flattened render of the 3D geometry. Instead of visualizing the antenna's rods, it time-integrates the real temporal coupled-mode equations for the bright and dark complex mode amplitudes with fourth-order Runge-Kutta, starting from rest every time a control changes, and plots each phasor's trajectory live on its own Argand plane as it spirals from the origin into its steady state. An oscilloscope-style strip chart tracks both mode intensities scrolling in real time against dashed analytic reference lines, while a separately computed extinction spectrum shows where the asymmetric Fano lineshape and its transparency dip sit across the full detuning range. Adjust drive detuning, bright-dark coupling and the two damping rates to watch the transient ring-up and the resulting steady state reshape together.