Investigation On Nd:YAG/YVO₄ And Yb:YAG/YVO₄ All-solid-state Raman Lasers

Stimulated Raman Scatting(SRS) based on third-order nonlinearity process has been widely utilized to extend the laser spectral coverage. Different laser wavelengths can be achieved by selecting the laser emission line and the Raman shift of Raman active medium. The combination of Raman conversion and other frequency conversion based on second-order nonlinearity process, such as second harmonic generation or sum- frequency generation, has been employed to generate the wavelengths covering the ultraviolet(UV) to the visible and infrared. As the improved growth methods of Raman active crystal, the all- solid-state Raman lasers have become a research focus.Based on the investigation on the development of Raman frequency conversion technology, different composite crystals were selected as laser medium to investigate the Raman output performance, combining proper Raman active medium and nonlinear medium. Investigations in this paper are as follows:(1) The passively Q-switched Raman output at 1176 nm was realized by using the Nd:YAG/Cr4+:YAG composite crystal and the YVO4 crystal. By employing a KTP crystal in the cavity, the frequency doubled laser at 588 nm was achieved. We investigated the output performance of lasers at 1176 nm and 588 nm with two different composite crystals which had different initial transmissions, such as average output power, the pulse width, the pulse repetition frequency(PRF) and output spectra and etc, which could lay theoretical and experimental foundations for these commercial Raman lasers.(2) We put forward Yb:YAG/Cr4+:YAG/YAG composite structure and demonstrated the 940 nm laser diode(LD) end-pumped composite crystal lasers. Based on different initial transmissions(T0) of Cr4+:YAG and different transmissions(TOC) of output coupler, the average output power, pulses and output spectra were investigated.(3) The end-pumped AO Q-switched Yb:YAG/YVO4 Raman lasers were experimentally demonstrated for what was believed to be the first time by employing separated Yb doped laser material and Raman crystal. We investigated the average output power as a function of the incident pump power with different PRFs as well as pulse profiles and spectra under different incident pump powers at a certain PRF.