1.3-μm 2.8-ns electro-optical cavity damping Nd:YVO₄ laser

Abstract

<sec>1.3-μm Nd laser has significant practical applications in various fields, such as fiber communication, medical treatment, frequency conversion, and scientific research. Many applications of a 1.3-μm laser, particularly frequency conversion, benefit greatly from a short pulse width with high peak power. In the paper, an electro-optical cavity dumping Nd:YVO₄ laser at 1342 nm wavelength is studied theoretically and experimentally.</sec><sec>The pulse width for an electro-optical cavity dumping laser is determined by the optical length of the cavity. A narrower pulse width is obtained by reducing the length of the cavity and the round trip time of the laser in the cavity. However, when the round trip time in the cavity approaches to the falling edge time of the electro-optical switch, shortening the length of the cavity will not obtain a narrower pulse width, and the falling edge time of the electro-optical switch will influence the laser pulse width. The temporal characteristics of the laser pulse are simulated when the falling edge time of the electro-optical switch is close to the round trip time in the cavity.</sec><sec>The influence of the falling edge time of the electro-optical switch on the laser pulse duration is analyzed theoretically. The modified rate equation is used to study the relationship between the falling edge time and the laser pulse width.</sec><sec>We demonstrate an electro-optical cavity dumping Nd:YVO₄ laser. The atom percent of 0.3% Nd:YVO₄ placed in a short Plano-concave cavity is in-band pumped by an 880 nm quasi-continuous-wave diode. A fiber-coupled diode laser module (<i>NA</i> = 0.22) with a power of 30 W is used. An LiNbO₃ electro-optical switch is employed for the cavity-dumping. The 1342-nm cavity-dumping laser operates at a repetition rate of 1 kHz, single-pulse energy of 0.21 mJ, and pulse width of 2.8 ns. Near-diffraction-limited beam quality with an <inline-formula><tex-math id="Z-20230713064624-1">\begin{document}$ M^2 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230014_Z-20230713064624-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230014_Z-20230713064624-1.png"/></alternatives></inline-formula>value of < l.2 is achieved. The setup uses MgO:PPLN crystal to generate efficient second harmonic at 671 nm, with a pulse width of 1.8 ns. To the best of our knowledge, this is the shortest pulse duration ever obtained from 1.3 μm actively <i>Q</i>-switched Nd-doped laser.</sec>