基于XeF(C-A)放大器的混合(固态/气态)超高功率飞秒激光系统

摘要

提出了基于前端发生器和终端放大器,使用光泵浦XeF(C-A)激活介质的太瓦级混合激光器(THIA00)系统.前端发生器由长532 nm的连续激光泵浦的钛宝石飞秒脉冲振荡器,脉冲展宽机构,532 nm的脉冲激光泵浦的再生多通道放大器,衍射光栅压缩器和二次谐波发生器(KDP)组成.其光束输出参数为:脉冲持续时间50 fs,二次谐波(475 nm)辐射能量5mJ.前端发生器以10 Hz的单脉冲模式工作.XeF(C-A)放大器由双高压脉冲发生器(线性变压器),爆炸式阴极发射真空二极管,电子束注入系统,充满Xe的气室转换器和激光单元组成.高压发生器包括12个变压器,每个变压器有8个电容(40 nF)和火花隙,电容可以充电至100 kV.真空二极管中的电子束参数为:总电流300 kA.峰值电压550kV,脉冲持续时间约150 ns.穿透金属箔片到达Xe转换器的6个100 cm × 12 cm电子束的总能量为6-7kJ.激光系统通过泵浦能量的级联处理导致Xe2的快速形成,并在(172±5) nm连续辐射.真空紫外辐射通过CaF2窗口辐射到含有XeF2燕汽和氮气缓冲气体的激光单元中,使XeF2光解,形成XeF*准分子.由真空紫外辐射泵浦的放大器激活介质长110cm,直径为24cm.文中通过数值模拟给出了输出参数和第一实验结果,根据XeF(C-A)放大器参数模型和增益测量结果,得到的输出能量高达2-3J,这意味着50 fs脉冲的峰值功率高达40-60 TW.%A terawatt hybrid laser (THL-100) system on the basis of a starting complex and a final amplifier with gaseous optically driven active media on XeF(C-A) molecules is presented. The starting complex manufactured consists of a Ti: sapphire master oscillator pumped by femtosecond pulses from a continuous laser pumped by (Verdy-8) at a wavelength of 532 nm, a femtosecond pulse stretcher, regenerative and multipass amplifiers pumped by a pulsed laser at a wavelength of 532 nm, a diffraction grating compressor and a second harmonic generator (KDp). The complex has the following output parameters of the laser beam: pulse duration is 50 fs, the energy of radiation at the second harmonic (475 nm) is 5 mJ. The complex can operate in a single pulse mode and a frequency of 10 Hz. The XeF(C-A) amplifier consists of a two high-voltage pulsed generator (linear transformer), a vacuum diode with six cold explosive-emission cathodes, a electron beam injection system, a Xe filled gas chamber-converter and a laser cell. The high-voltage generator consists of 12 transformer stages,and each of them involves eight capacitors (one is C=40 nF) and spark gaps. The capacitors can be charged up to voltage of 100 kV. E-beam in vacuum diode has the parameters in total current of 300 kA, peak voltage of 550 kV, pulse duration of e-beam power about 150 ns (FWHM). The total energies of the six 100 cm × 12 cm e-beams which pass through the foil into the Xe converter are 6-7 kJ in the 150-160 ns pulse (FWHM). Pump energy cascade processes lead rapidly to the formation of Xe2″, which radiates a fraction of the deposited energy in the continuum at (172 ± 5) nm. This VUV radiation is transmitted through CaF2 windows into the laser cell containing the mixture of XeF2 vapour and N2 buffer gas. VUV radiation makes photolysis of XeF2 molecules form XeF* excimer molecules. The active medium of the amplifier pumped by VUV radiation has 24 cm aperture and 110 cm length. The results of numerical modeling of the output parameters and first experimental results are presented in this paper. According to the modeling of the XeF(C-A) amplifier parameters and the first measurement of gain, it is shown that the maxmum output energy is 2-3 J,which means that the peak power has been up to 40-60 TW in a 50 fs pulse. Furthermore, It is very important that this laser system can provide a high temporal contrast up to 109-1010.