Nanosecond non-diffracting Bessel green beam generated directly from an unstable resonator by active method

Abstract

An intracavity frequency-doubled Nd∶YAG nanosecond Bessel green laser is designed in an axicon-based Bessel and Bessel-Gaussian resonator. The unstable laser resonator is composed of a refraction axicon and a convex mirror. The gain medium Nd∶YAG rod is pumped by a single flash-lamp which is working in a pulsed mode and a KTP crystal is used for intracavity second-harmonic generation. Nanosecond Bessel green beam is generated directly from the laser by active method when pumping voltage is 350 V. The pulse with width of 55.1 ns, central wavelength at 532 nm, spectral line width of 0.8 nm and diameter of central spot of 192 μm is obtained. Fresnel-Kirchhoff diffraction integral and the Fox-Li algorithm is used to extract the dominant mode of the cavity and the experimental results are consistent with those of the numerical simulation.