1.1.4 LGS E-O Q-switched laser

LGS crystal has stable physical and chemical properties, high damage threshold, high thermal stability, and high electromechanical coupling coefficient. However, LGS crystal has optical rotation effect. After taking measures to eliminate the optical activity, LGS crystal shows excellent performance in an E-O Q-switch. Same as BBO crystal, when LGS crystal is used (for its lateral E-O effect) to make E-O Q-switch, the driving voltage can be adjusted by changing the aspect ratio of the crystal. The latest information shows that the maximum repetition frequency of LGS E-O Q-switches can reach 1 MHz.

In 2010, researchers used LD to end-pump Nd:YVO₄ and a LGS E-O Q-switch to make laser output with repetition frequency 30 kHz, single pulse energy 200 μJ and pulse width 9.1 ns. The aspect ratio of the LGS crystal used in this Q-switch is 10:1. The quarter-wave voltage is only 1760 V which is beneficial to obtain a high repetition rate laser output. The device diagram of this LGS E-O Q-switched Nd:YVO₄ laser with high repetition rate is shown in the figure below.

In 2016, on the basis of solving the problem of the optical rotation effect of LGS crystal, researchers designed a single-pass short-cavity laser structure by using LGS crystal and achieved good laser performance, obtaining 1064 nm laser output with repetition frequency 200 kHz and pulse width 5.1 ns.