Laser Diodes Power Scaling Techniques

In the thesis the problem of laser power scaling and brightness improvement is addressed. The limits that the development of single laser devices (both semiconductor lasers and fiber lasers) has reached and hardly can overpass have been discussed and an overview on the different techniques to combine multiple lasers into a single beam with greater power and quality has been presented. Between them, for the promising results that have already been obtained and its importance in future research, coherent combining techniques have been investigated in detail. For this reason, a Master Oscillator Power Amplifier (MOPA) system seeded with a fiber laser have been numerically simulated on Matlab and the Stochastic Parallel Gradient Descent (SPGD) algorithm to actively correct the phase of the channels and maximize the on-axis intensity of the combined beam has been validated. In the last part of the thesis, another promising power scaling technique is considered. To this purpose, the results of an experiment on spectral beam combining, are described. Wavelength locking using as feedback the 1st order of a blazed diffraction grating has been demonstrated with multiple diodes.