Tapless and topology agnostic calibration solution for silicon photonic switches

We leverage the photo-conductance (PC) effect in doped phase-shifter heaters for both controlling and calibrating Mach-Zehnder interferometer (MZI) switch elements. Both the steady-state and the transient response are experimentally characterized, and compact models for the PC current are developed. Utilizing the PC effect, a topology-agnostic algorithm is then outlined. The calibration procedure is experimentally verified against calibration with external photo-detectors using a non-blocking 4×4 Benes switch consisting of six 2×2 MZIs. It is shown that our PC-based approach agrees with the PD-based procedure within less than 2.5% of difference between the obtained calibrated values. Based on the calibrated PC values, all possible routing configurations are measured for extinction ratio (9.92-21.51dB), insertion loss (0.88-4.59dB), and exhibiting performances far below the 7% FEC limit (bit error rate of 3.8 × 10 - 3 ) using 25 Gbps 4-level pulse-amplitude-modulation signals (PAM4).