High-energy 2 µm pulsed vortex beam excitation from a Q-switched Tm:LuYAG laser
Ying Chen, Manman Ding, Jianlei Wang, Li Wang, Qiyao Liu, Yongguang Zhao, Ying Liu, Deyuan Shen, Zhengping Wang, Xinguang Xu, Valentin Petrov
Abstract
We report on the first, to the best of our knowledge, direct generation of pulsed vortex beams at 2 µm from a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>Q</mml:mi> </mml:mrow> </mml:math> -switched Tm:LuYAG laser. High-energy Laguerre–Gaussian ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">L</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0</mml:mn> <mml:mo>,</mml:mo> <mml:mi>l</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) pulsed laser beams with well-defined handedness are selectively excited through spatially matched pump gain distribution and asymmetric cavity loss without using any intracavity handedness-selective optical elements. Pulse energies of 1.48 mJ for the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">L</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0</mml:mn> <mml:mo>,</mml:mo> <mml:mo>+</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> mode and 1.51 mJ for the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">L</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0</mml:mn> <mml:mo>,</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> mode, respectively, are achieved at a repetition rate of 500 Hz. The pulsed laser beams with helical wavefronts are potentially useful for studying orbital angular momentum transformation dynamics, generation of mid-IR vortex beams, and nanostructuring of organic materials.