This study discusses the importance of accurately calculating the optical response of Bragg gratings and the challenges associated with the 3D finite-difference time-domain (FDTD) method for simulating large-scale structures. The Bragg grating section in monolithic extended cavity diode lasers is of substantial size, making 3D FDTD simulations computationally challenging due to their complexity. In order to assess the accuracy of 3D simulations, we compare them with experimental results. Using a precise model design, involving a systematic analysis of simulation parameters, we obtain a good agreement between 3D FDTD simulations and the experimental results.

Acquiring a substantial number of data points for training accurate machine learning (ML) models is a big challenge in scientific fields where data collection is resource-intensive. Here, we propose a novel approach for constructing a minimal yet highly informative database for training ML models in complex multi-dimensional parameter spaces. To achieve this, we mimic the underlying relation between the output and input parameters using Gaussian process regression (GPR). Using a set of known data, GPR provides predictive means and standard deviation for the unknown data. Given the predicted standard deviation by GPR, we select data points using Bayesian optimization to obtain an efficient database for training ML models. We compare the performance of ML models trained on databases obtained through this method, with databases obtained using traditional approaches. Our results demonstrate that the ML models trained on the database obtained using Bayesian optimization approach consistently outperform the other two databases, achieving high accuracy with a significantly smaller number of data points. Our work contributes to the resource-efficient collection of data in high-dimensional complex parameter spaces, to achieve high precision ML predictions.

Here we introduce efficient machine learning models trained on a 3D FDTD simulation-based database to predict Bragg grating characteristics from the main and the side lobes of reflectance spectra fitted by coupled mode theory.