Two decades of INO research on laser arrays

We summarize in this work the salient points of the studies carried out at the National Institute of Optics (INO) in Florence in the vast field of coherent laser arrays. The research began in the early 90s under the push of Tito Arecchi with the study of coupled laser oscillators. These systems stimulated Tito's curiosity by representing an accessible sample of nonlinear oscillator chains. In the following years at INO we continued our research in this field, obtaining numerical and experimental results both with the realization of laser arrays and in the field of their possible application. Of particular importance for obtaining a fruitful application was the development of optical phase filtering techniques aimed at increasing the optical quality of the beam emitted from these sources, which is actually far from having a traditional geometry.