SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Phys Rev Lett. 2012 Aug 17;109(7):074801. doi: 10.1103/PhysRevLett.109.074801. Epub 2012 Aug 16.
We report generation of density modulation at terahertz (THz) frequencies in a relativistic electron beam through laser modulation of the beam longitudinal phase space. We show that by modulating the energy distribution of the beam with two lasers, density modulation at the difference frequency of the two lasers can be generated after the beam passes through a chicane. In this experiment, density modulation around 10 THz was generated by down-converting the frequencies of an 800 nm laser and a 1550 nm laser. The central frequency of the density modulation can be tuned by varying the laser wavelengths, beam energy chirp, or momentum compaction of the chicane. This technique can be applied to accelerator-based light sources for generation of coherent THz radiation and marks a significant advance toward tunable narrow band THz sources.
我们通过激光调制束的纵向相空间，在相对论电子束中产生太赫兹（THz）频率的密度调制。我们表明，通过用两束激光调制束的能量分布，可以在束通过扭曲波荡器后，在两束激光的差频处产生密度调制。在这个实验中，通过下转换 800nm 激光和 1550nm 激光的频率，产生了大约 10THz 的密度调制。通过改变激光波长、束能啁啾或扭曲波荡器的动量压缩，可以调节密度调制的中心频率。该技术可应用于基于加速器的光源，以产生相干 THz 辐射，标志着朝着可调谐窄带 THz 源迈出了重要一步。
