Dianyang Lin

Pulse temporal compression by two-stage stimulated Brillouin scattering and laser-induced breakdown

A laser pulse temporal compression technique combining stimulated Brillouin scattering (SBS) and laser-induced breakdown (LIB) is proposed in which the leading edge of the laser pulse is compressed using SBS, and the low intensity trailing edge of the laser pulse is truncated by LIB. The feasibility of the proposed scheme is demonstrated by experiments in which a pulse duration of 8 ns is compressed to 170 ps. Higher compression ratios and higher efficiency are expected under optimal experimental conditions.

Residual pulse peak reduction in stimulated brillouin scattering optical limiting by an injected seed

A new method to reduce the residual pulse peak in stimulated Brillouin scattering (SBS) optical limiting by an injected seed is presented. The pulse shapes of the transmitted pump beam are studied for various delay times and injected seed powers theoretically. The numerical simulated results show that the height of the residual pulse peak can be controlled by changing the delay time and injected seed intensity. Experimentally, various optical limiting pulse shapes with different heights of the residual peak are observed by changing the delay time and intensity of the seed injected into the SBS optical limiter. The experimental and theoretical results show that the residual pulse peak in SBS optical limiting can be controlled by the delay time and power of an injected seed.

The compression of ASE pulses using optical breakdown clipping in liquid

Using the method of optical breakdown clipping on Krypton Fluoride excimer laser, ASE (Amplified Spontaneous Emission) pulse compression technology was studied in this paper. And the liquid medium breakdown depth on the ASE pulse compression effect was analyzed. The initial ASE pulse width was16.8ns, the shortest 8.4ns ASE pulse was obtained in the experimental. The auxiliary beam induced luminescence breakdown was used to study on the law of optical breakdown clipping, and the short 7.3ns ASE pulse was got. These experimental results proved that the auxiliary beams are useful to accelerating the plasma generation rate and duration. The results ASE pulse compression can be controlled in some degree.

The influence of smoothing by spectral dispersion on the beam characteristics in the near field

The influences of SSD on the beam characteristics in the near field are investigated. Results show that if the SSD parameters are increased, the laser intensity modulation increases while fluence modulation decreases, which is attributed to the temporal and spatial variation of the SSD pulse phase. The variations of intensity and fluence modulations with the SSD parameters are given. The simulation results are presented along with a method for choosing appropriate SSD parameters according to the variations and the requirements of applications.

The performance of stimulated Brillouin scattering pulse improved by a prepulse seed

SBS with a prepulse injection has been investigated through experiment. We have measured the threshold, waveform fidelity, energy reflectivity, stability and discussed the factors which lead to the changes of output pulse shape, and also the principles are achieved. Results show that a suitable delayed time between the prepulse and the main-pulse can shorten the leading edge and enhance the fidelity. A suitable energy ratio of the prepulse to the main-pulse can improve the reflectivity stability. The result indicates that the experimental program can improve the waveform of the Stokes pulse and the stability of the reflectivity. Theoretical calculation formula is used to simulate these results numerically. The threshold and energy reflectivity are also studied. And the theoretical results are consistent with that of experiment.

Influence of medium parameters on the characteristic of power limiting based on stimulated Brillouin scattering

Adopting noise initiation mode of stimulated Brillion scattering (SBS), the influence of phonon lifetime and gain coefficient of medium on power limiting characteristic is numerically investigated. By using actual parameters of three media, CCl4, Acetone, and CS2, the waveforms of transmitted pulses are simulated. It shows that, different media have little effect on the front peak of waveform, while have an obvious effect on the height of power limiting platform. When using the medium which has short phonon lifetime and small gain coefficient, the height of power limiting platform is comparatively high. When using the medium which has long phonon lifetime and large gain coefficient, the height of power limiting platform is comparatively low. In experiment, focusing 1064nm, 8ns, 18mJ pulses into these three media respectively, the waveforms of transmitted pulses are obtained. And it is shown that, the experimental results are in good agreement with the conclusions of theoretical simulations.