Wang Zhenyou, Su FuHai, Hegmann Frank A
Opt Express. 2015 Mar 23;23(6):8073-86. doi: 10.1364/OE.23.008073.
We use ultrafast phase-contrast imaging to directly observethe cone-like terahertz (THz) Cherenkov wave generated by optical rectification of femtosecond laser pulses focused into bulk lithium niobate (LiNbO₃) single crystals. The transverse imaging geometry allows the Cherenkov angle, THz wave velocity, and optical pump pulse group velocity to be measured. Furthermore, transition-like THz radiation generated by the femtosecond laser pulse at the air-crystal boundary is observed. The effect of optical pump pulse polarization on the generation of THz Cherenkov waves and transition-like radiation in LiNbO₃ is also investigated.
我们使用超快相衬成像技术直接观察聚焦到块状铌酸锂（LiNbO₃）单晶中的飞秒激光脉冲通过光学整流产生的锥形太赫兹（THz）切伦科夫波。横向成像几何结构允许测量切伦科夫角、太赫兹波速度和光泵浦脉冲群速度。此外，还观察到飞秒激光脉冲在空气 - 晶体边界处产生的类似跃迁的太赫兹辐射。还研究了光泵浦脉冲偏振对LiNbO₃中太赫兹切伦科夫波和类似跃迁辐射产生的影响。
