Complete model identification using laser impulse response for measuring the data age of photodetector in dynamic interferometry

We present a model identification technique for measuring the photodetector data age, with great potential for compensating and eliminating non-real-time and nonlinear errors in dynamic interferometry. To the best of our knowledge, the proposed method identifies the most complete photodetector model, consisting of a transfer function and a fixed delay. The model is constructed by analyzing impulse response sequences with Hankel matrix and phase spectrum analysis, based on which the phase shift and integral time delay of the photodetector are accurately determined. Experimental outcomes indicate that the proposed method achieves a model reliability of 95% and a measurement uncertainty of 51 ps (k=2) for the data age of a photodetector with a bandwidth of 400 MHz. Compared to existing methods, this approach significantly improves the accuracy, continuity, and practicality of measuring data age in photodetectors.