A passively Q-switched mode-locked(QML) Tm:Li Lu F4(LLF) laser with a Mo S2 saturable absorber(SA) is demonstrated for the first time, to our best knowledge. For the Q-switching mode, the maximum average output power and Q-switched pulse energy are 583 m W and 41.5 μJ, respectively. When the absorbed power is greater than 7.4 W, the passively QML pulse is formed, corresponding to an 83.3-MHz frequency. The modulation depth in Q-switching envelopes is approximately 50%. Results prove that Mo S2 is a promising SA for Q-switched and QML solid-state lasers.
We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation(SPM), we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation(MPM) effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.
We theoretically study the nonlinear compression of picosecond pulses with 10-m J of input energy at the 1053-nm center wavelength by using a one-meter-long gas-filled hollow-core fiber(HCF)compressor and considering the third-order dispersion(TOD)effect.It is found that when the input pulse is about 1 ps/10 m J,it can be compressed down to less than20 fs with a high transmission efficiency.The gas for optimal compression is krypton gas which is filled in a HCF with a 400-μm inner diameter.When the input pulse duration is increased to 5 ps,it can also be compressed down to less than 100 fs efficiently under proper conditions.The results show that the TOD effect has little impact on picosecond pulse compression and the HCF compressor can be applied on compressing picosecond pulses efficiently with a high compression ratio,which will benefit the research of high-field laser physics.
