Global research methods for optical device characterization

A review on the global research methods for design and characterization of optical material and devices is reported. As an example, the recovering of the homogeneous upconversion coefficients (HUCs) in Er³⁺-doped activated devices is illustrated. Particle Swarm Optimization (PSO), Artificial Neural Network (ANN) and Genetic Algorithm (GA) approaches are briefly described. These algorithms have been used to find the optimal erbium doped fibre amplifier or laser configuration, and to identify those parameters of the erbium energy level transitions for which direct measurements are not feasible or are not easily performed. In particular, the HUCs are calculated on the basis of known values of optical gain evaluated in different pumping conditions, by employing different global research, home-made, computer codes. The simulation results demonstrate that the proposed global research techniques provide solutions that are very close to the expected values. The described methods constitute intriguing tools for the design and optimization of rare-earth doped lasers and amplifiers and feasible alternative methods in the field of material science and optical engineering. The codes can be easily extended to rare earth co-doped glasses or amplifiers/lasers for determining the optical parameters, as the ion-ion interaction ones, avoiding the employment of expensive equipment for their measurement.