Paper-The formation of quasi-nondiffracting focused beams with second-harmonic generation of flower Laguerre–Gaussian modes

Y C Lin, K F Huang and Y F Chen

yfchen@cc.nctu.edu.tw

Department of Electrophysics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30050, Taiwan 

http://iopscience.iop.org/1555-6611/23/11/115405?rel=ref&relno=10

Paper 

We theoretically demonstrate that the second-harmonic generation of a flower Laguerre–Gaussian mode can be exploited to form a quasi-nondiffracting focused beam. It is verified that the product of donut Laguerre–Gaussian modes with opposite topological charges leads to the formation of the quasi-nondiffracting focused beam. The divergence of the quasi-nondiffracting focused beam is numerically confirmed to be  times less than that of the Gaussian TEM₀₀ mode with the same beam waist parameter, where l is the azimuthal index of the flower Laguerre–Gaussian mode. In an experiment, we employ a diode-pumped solid-state laser resonator with intracavity second-harmonic generation to realize the formation of the quasi-nondiffracting focused beams.