量子级联激光种子注入高重频窄脉冲CO2激光再生放大技术

13.5nm EUV ligh source is excepted to be used for the next generation lithography. The source usually uses a high power CO2 MOPA system as the driver laser, the MOPA system is based on a small power high repetition short pulse master oscillator and a chain of power amplifiers. The master oscillator usually employed Q switching and cavity dumping techniques to generate trains of CO2 laser short pulses, which are not sufficiently resistant to the parasitic back-seeding by amplified spontaneous emission(ASE) from MOPA system amplifiers. Resulting in insufficient control over the timing of laser pulse. In this project, we will build a new oscillator featured quantum cascade laser seeders and a radio frequency discharge excited, diffusion- cooled, slab-waveguide CO2 gas cell in a compact multipass long cavity regenerative amplifier configuration. The long cavity coupling with the relatively high intensity of the seeding pulses is helpful to suppress the buildup of the undesired cavity eigenmodes, the spectral and temporal output of the new oscillator is decided by the seeding pulse. Resulting in a high resistance to ASE. Multi TTL signals are used to control the time of seeding injection, opening and closing of the cavity,which can acertain the regenerative amplifier operate efficiently.The compact multipass long cavity configuration ascertains a power gain factor as high as 10^6 is achievable after a few round trips. The shaping optics is implemented as an aperture placed at the point where the beam waist locates. After that, the laser beam can quickly converge to a final state, allowing us to get a high quality beam. Implemention of the project will circumvent a several technical difficulties that so far limited the high repletion nanosecond pulse performance of CO2 MOPA. The new oscillator also has the potential for successful application in high speed laser material processing and laser ranging.

13.5nm极紫外光刻光源的驱动源--高功率CO2激光MOPA系统的前级低功率窄脉冲振荡器存在抗干扰能力差、激光脉冲不稳定等瓶颈问题。本项目拟采用QCL激光和新型多程长腔射频CO2激光再生放大技术结合实现稳定性高、抗干扰能力强的高重频窄脉冲CO2 激光输出。该技术能有效抑制放大器谐振腔本征模的建立，再生放大器输出激光脉冲特性由种子脉冲决定，大大增强了振荡器对ASE的抗干扰能力；采用多路TTL信号同步控制实现种子注入、Q开关开启和关闭时刻的精确控制，确保再生放大器高效运转；多程折叠长腔结构，保证种子激光脉冲在腔内经过几次往返后获得大于10的六次方以上的放大倍数，同时确保放大器的紧凑性。采用滤波小孔技术，使得光束直径快速收敛到稳定状态，获得高光束质量激光输出。本项目有望解决解决极紫外光源应用中CO2激光 MOPA系统振荡器长期存在的瓶颈问题，在高速激光精密加工和激光探测领域也有很好的应用前景。

13.5nm极紫外光刻光源的驱动源——高功率CO2激光MOPA系统的前级低功率窄脉冲振荡器存在抗干扰能力差、激光脉冲不稳定等瓶颈问题。本项目采用QCL激光和新型多程长腔射频CO2激光再生放大技术结合实现稳定性高、抗干扰能力强的高重频窄脉冲CO2激光输出。该振荡器实现了脉冲包络、脉冲能量和光谱高稳定性的激光输出。激光平均功率达到15W，脉冲宽度12ns，重复频率100kHz,M2因子小于1.3，光束指向稳定性小于50rad。本项目有望解决解决极紫外光源应用中CO2激光 MOPA系统振荡器长期存在的瓶颈问题，在高速激光精密加工和激光探测领域也有很好的应用前景。