Thermal Crosstalk Modelling and Compensation Methods for Programmable
  Photonic Integrated Circuits
Isidora Teofilovic Ali Cem David Sanchez-Jacome Daniel Perez-Lopez Francesco Da Ros
Photonic integrated circuits play an important role in the field of optical
computing, promising faster and more energy-efficient operations compared to
their digital counterparts. This advantage stems from the inherent suitability
of optical signals to carry out matrix multiplication. However, even
deterministic phenomena such as thermal crosstalk make precise programming of
photonic chips a challenging task. Here, we train and experimentally evaluate
three models incorporating varying degrees of physics intuition to predict the
effect of thermal crosstalk in different locations of an integrated
programmable photonic mesh. We quantify the effect of thermal crosstalk by the
resonance wavelength shift in the power spectrum of a microring resonator
implemented in the chip, achieving modelling errors <0.5 pm. We experimentally
validate the models through compensation of the crosstalk-induced wavelength
shift. Finally, we evaluate the generalization capabilities of one of the
models by employing it to predict and compensate for the effect of thermal
crosstalk for parts of the chip it was not trained on, revealing
root-mean-square-errors of <2.0 pm.