Simultaneous self-mode-locking of TEM0,0 and TEM1,0 modes in a Nd:YVO4 laser: Application for measuring the thermal focal length

Short pulse width UV laser at 355 nm based on pulse LD side-pumped ceramic Nd:YAG and BBO electro-optical Q-switched

“…Delay triggering time of the two signals is adjusted to ensure that the emission of 808 nm pulse pumped light by LD syn chronizes exactly with the voltage decrease of BBO crystal. M 1 is a total reflection mirror at 1064 nm coated near one side of the electro optical crystal; M 2 is an output mirror (convex radius of curvature was 500 mm) with fundamental frequency beam at 1064 nm, and optimum transmittance T = 67% is chosen according to transmittance comparative experiment; Brewster plate (2 mm thickness by 12 mm diameter) is placed between the BBO electro optical crystal and the ceramic Nd:YAG rod, and the sub tended angle between the mirror surface and optic axis of resonant cavity is 33.7° to make the fundamental frequency beam in the cavity oscillate only in the p polarization direction so as to turn off the electro optical Q switch effectively; the 808 nm pulse LD side pumped module, frequency doubling crystal and sum frequency crystal are cooled by external circulat ing water, and the temperature of the water was kept at 21°C, with a temperature control accuracy of ±0.1°C, in order to avoid thermal lens effect [14][15][16][17].…”

“…Using the formula E = P av /f [16], we obtain single pulse energy E of 355 nm UV pulse laser at different repetition rates, which changes with LD pump cur rent, as shown in Fig. 6.…”