Vπ Fitter
Paste a modulator bias sweep and get the numbers: the full cosine transfer function is fitted to every point, returning Vπ, extinction ratio, and bias phase, with residuals you can inspect. Fitting beats reading peak-to-null distance off two points, and the validation table shows you by how much. Companion procedure: Measuring modulator Vπ and EO bandwidth.
Two columns per line: bias voltage, then transmission. Comma, tab, or space separated. Any power units work; dB is detected automatically (or force it below).
The example is a synthetic 1.73 V device with realistic noise, drift-free. The fit is a one-dimensional scan over Vπ with an exact linear least-squares solve at each trial (the model is linear in offset and quadrature amplitudes), then golden-section refinement. No starting guess, no divergence.
The transfer model is P(V) = C + B cos(πV/Vπ + φb). For silicon depletion devices the phase is nonlinear in voltage, so treat the result as the local Vπ over your sweep window. Method details and pitfalls: Measuring modulator Vπ and EO bandwidth.
These validation rows run in your browser on every load: the fitter is exercised on synthetic sweeps with known answers, including the clipped-sweep case where peak-picking fails.
| Check | Expected | Computed |
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