Engineering Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Opt Lett. 2013 Mar 15;38(6):833-5. doi: 10.1364/OL.38.000833.
We demonstrate an approach for picosecond probe-beam generation that enables hybrid femtosecond/picosecond pure-rotational coherent anti-Stokes Raman scattering (CARS) measurements in flames. Sum-frequency generation of bandwidth-compressed picosecond radiation from femtosecond pumps with phase-conjugate chirps provides probe pulses with energies in excess of 1 mJ that are temporally locked to the femtosecond pump/Stokes preparation. This method overcomes previous limitations on hybrid femtosecond/picosecond rotational CARS techniques, which have relied upon less efficient bandwidth-reduction processes that have generally resulted in prohibitively low probe energy for flame measurements. We provide the details of the second-harmonic approach and demonstrate the technique in near-adiabatic hydrogen/air flames.
我们展示了一种皮秒探针光束产生方法，该方法可实现火焰中混合飞秒/皮秒纯旋转相干反斯托克斯拉曼散射（CARS）测量。飞秒泵的带宽压缩皮秒辐射的和频产生具有相位共轭啁啾的皮秒辐射，为探针脉冲提供超过 1mJ 的能量，并且与飞秒泵/斯托克斯准备时间锁定。该方法克服了以前混合飞秒/皮秒旋转 CARS 技术的限制，这些技术依赖于效率较低的带宽减小过程，通常导致火焰测量的探针能量极低。我们提供了二次谐波方法的详细信息，并在近绝热氢/空气火焰中演示了该技术。
