High-order Laguerre-Gaussian mode laser generated based on spherical aberration cavity

The high-order Laguerre-Gaussian (LG) mode output from an end-pumped Nd:YVO<sub>4</sub> laser cavity with strong spherical aberration (SA) induced by short-focal-length lens is studied in this work. A long-focal-length L1 used the to expand and collimate beam, so that beam incident on another L2 undergoes a SA. Since ring-shaped LG modes different values of angular index <i>m</i> have radii, actual focal points each order are then spatially displaced. flat coupler (OC) located near point L2, which composed cat-eye retroreflector together lens. Such can provide only ideal retroreflection exactly OC. Given displacements beams orders, such mechanism be for implementing transverse selection. has OC smaller loss than other defocused modes. With <i>a</i>-cut as crystal, scalar (linear-polarized) single-mode radical <i>p</i> = 0 <i>m</i>>0 obtained. mode-order selectable LG<sub>0, ±10</sub> ±33</sub> under 878.6-nm diode pump power 1.03 W, simply adjusting distance between range 0.5 mm, when using <i>f</i> 150 mm 33.9 mm. It found sufficient SA makes optical paths neighboring well distinguishable essential operation wanted mode. However, too stop oscillating, since width radius increasing function indices <i>m</i>, bring stronger corresponding Based analysis, we turn focal-length combination <i>f</i><sub>1</sub> 100 <i>f</i><sub>2</sub> 51.8 reduce level suitable further higher operation. highest-order ±75</sub> obtained mode-selecting technique fixed W.