论文标题
由自由电子激光振荡器产生的几个周期级超高脉冲的完整表征
Full characterization of few-cycle superradiant pulses generated from a free-electron laser oscillator
论文作者
论文摘要
第一次揭示了由自由电子激光器（FEL）振荡器产生的几个周期超级脉冲的详细结构。如数值模拟中所预测的那样，所获得的脉冲结构具有响铃，即在主脉冲之后的子杆列。由于相结合了线性和非线性自相关测量值的相结合，还通过脉冲形状获得了时间相，并确认了每个脉冲之间的$π$ - 相跳。这种特殊的脉搏形状具有$π$ - 相跳跃是Burnham-Chiao铃声或超级振铃的常见特征。使用未支配的FEL模拟，发现振铃起源于跨连续的束切片的重复形成和微置的变形。模拟结果表明，由于沿FEL振荡器的下降器的强大调制，FEL脉冲应进行静脉传播。
The detailed structure of few-cycle superradiant pulses generated from a free-electron laser (FEL) oscillator was experimentally revealed for the first time. As predicted in numerical simulations, the obtained pulse structures have ringing, i.e., a train of subpulses following the main pulse. Owing to the phase retrieval with a combination of linear and nonlinear autocorrelation measurements, the temporal phase was also obtained with the pulse shape, and $π$-phase jumps between each pulse were confirmed. This particular pulse shape with $π$-phase jumps is a common feature of Burnham-Chiao ringing or superradiance ringing. Using unaveraged FEL simulations, the ringing was found to originate from repeated formation and deformation of microbunches across successive bunch slices. The simulation results imply that there should be superluminal propagation of the FEL pulse due to strong gain modulation along the undulator of the FEL oscillator.
