Coherence and Phase-Locking in High-Power, Broad-Area, Highly Heterogeneous Blue Diode Laser Arrays

We have studied the dynamical routes toward phase-locking of coupled, high-power, highly heterogeneous, low fill factor arrays of blue diodes. We have demonstrated coherent beam combining and phase locking of large groups of lasers in linear 1D array of high-power, broad-area laser diodes emitting around 443 nm. The phase locking was confirmed by measuring clear and stable far-field interference fringes and comparing with a numerically calculated far-field intensity profile. The laser array can be tuned between in-phase and out-of-phase super modes by slightly changing the tip-tilt angle of the diffraction grating. Theoretical simulations of the far-field confirm the experimental observations while numerical simulations based on the Lang-Kobayashi model together with experimental observations indicate that the road to coherence in large arrays of lasers involve chimera and clustering states in the nonlinear dynamics triggered by external optical feedback. Overall, the experimental and numerical efforts presented in this work pave the way toward high-power emission at blue wavelength while maintaining superior beam quality and narrow line width.