<title>Novel methods of intracavity beam shaping</title>

Abstract

ABSTRACT Methods of shaping laser beams within the laser resonator are studied. The simplest form of shaping is the spatial modegeneration inherent in the laser cavity due to the geometry of the resonator in conjunction with gain to compensate forroundtrip losses, such as diffraction and output coupling. Typically the fundamental mode or multimode behavior isexhibited from such configurations. Passive mode shaping can be accomplished by introducing static amplitude or phasemasks. An example of an amplitude mask is provided in order to generate a higher-order spatial mode. Active mode shapingcan be accomplished by altering the optical pump distribution. This case is studied experimentally with a diode-end-pumpedNd:YVO 4 laser and compared to modeling of expected Hermite-Gaussian mode generation. Active mode shaping allows thepreferred mode distribution to be altered in real time. Additional shaping can be done following the resonator to modify aHermite-Gaussian mode into a psuedo-Laguerre-Gaussian mode. This work also shows that using the coherent propagationmethod of Gaussian beam decomposition is capable of modeling and describing intracavity beam shaping.Keywords: laser beam shaping, transverse modes, solid-state lasers, laser resonator, coherent propagation, Hermite-Gaussianmode, Laguerre-Gaussian mode