RESUMO
Coherent beam combining in the femtosecond regime of a record number of 19 fibers is demonstrated. The interferometric phase measurement technique, particularly well suited to phase-lock a very large number of fibers, is successfully demonstrated in the femtosecond regime. A servo loop is implemented to control piezoelectric fiber stretchers for both phase and delay variation compensation. The residual phase errors are below λ/60 rms. Nearly 50% of the total energy is contained in the far-field central lobe. After compression, we obtain a combined pulse width of 300 fs identical to the master oscillator pulse width.
RESUMO
We present a new configuration of quadriwave lateral shearing interferometer dedicated to phase detection for beam-combining purposes. Assuming that the fibers are disposed in a matrix arrangement, our scheme gives direct access to the phase step between adjacent fibers in two dimensions. Experimentally recorded interferograms are made only of two-wave interference fringes that scroll as the phase evolves in the fibers. This simplicity allows fast treatment by the spatial demodulation process, and the phase map from the fibers can be estimated in real time. No external reference is required, and the technique is fully compatible with a high number of fibers.
RESUMO
We present a new method of realizing phase plates by phase-volume holography on a photopolymer film. We implement such a component in a diode-pumped Nd:YAG oscillator to control the output spatial beam profile. Flattop super-Gaussian and square-shaped beams are obtained.
RESUMO
We present a new beam-shaping technique with an intracavity optically addressed liquid-crystal spatial light modulator. The Nd:YAG resonator is able to deliver beams with various spatial profiles such as flat-topped super-Gaussian and square-shaped beams.