Flat-top phase-matched high-order harmonics in gas-filled cell

Phase-matched high-order harmonic generation in Ar gas-filled cell is investigated experimentally. We obtain phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 mJ/pulse energy level and 1-kHz repetition rate. Moreover, we find that the spatial distribution of intensity of high-order harmonics is flat-top profile other than a Gaussian one under the condition of optimized conversion efficiency in the static gas cell.     

Flat-top phase-matched high-order harmonics in gas-filled cell

Phase-matched high-order harmonic generation in Ar gas-filled cell is investigated experimentally. We obtain phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 m J/pulse energy level and 1-kHz repetition rate. Moreover, we find that the spatial distribution of intensity of high-order harmonics is flat-top profile other than a Gaussian one under the condition of optimized conversion efficiency in the static gas cell.     

Improvement of the large aperture Ti：sapphire amplifiers in the petawatt femtosecond laser system at SIOM

We report the recent improvement on the petawatt (PW) femtosecond Ti:sapphire chirped pulse amplification (CPA) laser system at Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences. By enlarging the sizes of the pump and signal beams in the large aperture Ti:sapphire amplifiers and optimizing the whole laser system, the output laser energy before the pulse compressor is upgraded to 42.6 J. Accordingly, the peak power of the laser system exceeds 1 PW. The shot-to-shot instability of the output laser energy at about 40 J is less than ±5%.     

应用全反射二阶自相关仪测量超短脉冲脉宽

计算了普遍采用的二阶单发自相关仪光路中的分束片的色散引起的超短脉冲展宽量，指出在脉冲极短时该展宽将导致不准确的测量结果(例如，对于脉冲宽度为3fs左右，通过100μm厚度的K9玻璃分束片，脉冲展宽将达到10％)。基于计算结果，提出了一种新型的采用全反射结构的单发二阶自相关仪设计，通过分波面的方法改变了自相关仪的分束方式，避免了采用透射分束光学元件引起的色散。采用这种全反射式结构的二阶单发自相关仪，可以使自相关测量方法测得的脉冲宽度更为准确，计算得出理论上其最小时间分辨率可达3．6fs。     

High-power output from a compact OPCPA laser system

With a tabletop hybrid Nd:YAG-Nd:glass laser as pump source, a compact optical parametric chirpedpulse amplification(OPCPA)laser system with a peak output power of 16.7 TW and a pulse duration of120 fs has been demonstrated.Chirped pulses are amplified from 50 pJ to more than 3.1 J with an energygain of above 6×10~(10)by three LBO optical parametric amplifiers with a pump energy of 12.4 J at 532nm.After compression, a final output of 2.0-J/120-fs pulse is obtained. To the best of our knowledge,itis the highest peak output power from an OPCPA laser so far.In addition, a practical design of 1-PWlaser system based on the technique of OPCPA is also proposed.