Experimental study of all-solid-state second harmonic and fourth harmonic generation in Ti:sapphire laser

Second harmonic and fourth harmonic are generated by Ti:sapphire laser pumped by a diode laser pumped Q-switched, frequency doubled YLF laser at 527 nm. The nonlinear crystal LBO is used to generate the second harmonic in the Ti:sapphire laser cavity at type I phase match with birefringent filter respectively, and BBO is used to generate ultraviolet laser at 208 nm. The maximum average power of 410 mW at 415 nm, and 34 mW at 208 nm are obtained at 1 kHz repetition rate when the pumping power is 3.6 W. The relations between linewidth of fundamental wave and harmonic efficiency, wavelength of fundamental wave and fourth harmonic efficiency, the effects of birefringent filter on pulse width and line width of Ti:sapphire laser, and the dependence of line width of Ti:sapphire laser with birefringent filter on pumping power are investigated in theory and experiment.