Spatial field control of broad area semiconductor lasers with integrated grating couplers

In this research, a method of designing a grating outcoupler to obtain the desired 2D-intensity profile and improved field distribution of the optical beam emitted by a grating coupled surface emitting laser is presented. The method is based on variation of the periodicity, duty cycle, and the groove tilt angle of the grating. Grating design involves numerical analysis of the optical field propagated through the grating, by applying the Rigorous Coupled Wave Approach method. Experimental evaluation of the designed grating components was done by fabrication and testing the broad area semiconductor lasers with the monolithically integrated grating outcouplers. Another grating design is presented that provides the spreading of a single optical output into multi-beams at different outcoupling angles in the emitting plane. Using field distribution presentation, an approach to provide uniform optical intensity profile from the grating outcoupler based on varying duty cycle is described. Furthermore, this work presents experimental evaluation of 1D, and 2D (8x8) square, arrays of phase-locked surface-emitters including semiconductor optical amplifiers spaced by grating outcouplers. The phase-locked multi-emitter design was based on the master oscillator power amplifier (MOPA) array approach. As the MO for the 1D array we used a monolithically integrated grating coupled laser with wavelength stabilization and a fiber coupled external laser source was used for the 2D array. Mutual coherence was experimentally evaluated by interference investigation and the obtained results were compared to numerical modeling