Experimental And Theoretical Research On LD Pumped Nd:Y_0.5Lu_0.5VO₄ Pulsed Laser

LD pumped solid-state pulse lasers with high peak power,short pulse width and high beam quality, which have many merits such as small size, light weight, firm structure,long life duration, high stability and high conversion efficiency, have been widely used in the scope of military, industry, medical treatment and scientific researches. As one of the main objectives of current research and development activities within the laser community.,LD pumped solid-state pulse lasers is constantly improving and fast developing,such as the constant improvement of output power,spatial beam quality and the decrease of pulse width。The foundation of those development is selection of gain medium having perfect performance. In this paper, we experimentally and theoretically investigate the output performance of AO, passively and dual-loss Q-switched Nd:Y_0.5Lu_0.5VO₄ lasers by simultaneously adopting the AO and saturable absorbers Cr⁴⁺:YAG in laser cavity as Q-switch. The central contents have been summed up as below:1. Review of the history and development of all solid state lasers, and the main approaches and new improvements of Q-switching pulse lasers nowadays are summarized. The optical properties of several Nd-doped mixed vanadate crystals are simply introduced and compared with each other.2. We present a diode end-pumped acousto-optic (AO) Q-switched Nd: Y0.5Lu0.5VO4 crystal laser emitting at 1064 nm. The laser can generate short pulse duration and high peak power with a comparative simple planar-planar cavity by optimum design. For Q-switching operation, at the incident pump power of 14.09 W , the 1 KHz repetition rate and the output transmission of 50%, we get the shortest pulse width of 8.3 ns , the measured highest single pulse energy of 2.15 mJ and the measured highest peak power of 249 KW. If the intracavity photon distribution is assumed to be a Gaussian spatial distribution, a coupled equation of AO Q-switched laser is given to theoretically analyze the experimental results and leads to a good agreement with the experimental data. 3. We present for the first time a diode end-pumped Cr⁴⁺:YAG passively Q-switched Nd: Y_0.5Lu₍0.5_VO₄ crystal laser emitting at 1064 nm by employing a set of output couplers to optimize the laser performance. For Q-switching operation, at the incident pump power of 14.09 W, the average output power of 1.21 W, the measured shortest pulse duration of 9.4 ns and the highest pulse energy of 14.2μJ are respectively obtained for the output transmission of 30%, when the Cr⁴⁺: YAG crystal with an initial transmission (T0) of 60% is used. If the intracavity photon distribution is assumed to be a Gaussian spatial distribution, a coupled equation of Cr⁴⁺:YAG passively Q-switched laser is given.4. The output performances of LD pumped AO/Cr⁴⁺:YAG double Q-switched Nd: Y0.5Lu0.5VO4 lasers at 1064 nm are demonstrated, and the average output power, pulse duration, peak power are measured experimentally. The double Q-switched laser can generate shorter pulse duration and high peak power when compared with that obtained by single Q-switched laser. If the intracavity photon distribution is assumed to be a Gaussian spatial distribution, a coupled equation of AO/Cr⁴⁺:YAG double Q-switched laser is given to theoretically analyze the experimental results and leads to a good agreement with the experimental data.