Generating carrier-envelope-phase stabilized few-cycle pulses from a free-electron laser oscillator

Determining the carrier-envelope phase of intense few-cycle laser pulses

The electromagnetic radiation emitted by an ultra-relativistic accelerated electron is extremely sensitive to the precise shape of the field driving the electron. We show that the angular distribution of the photons emitted by an electron via multiphoton Compton scattering off an intense ($I>10^{20}\;\text{W/cm$^2$}$), few-cycle laser pulse provides a direct way of determining the carrier-envelope phase of the driving laser field. Our calculations take into account exactly the laser field, include relativistic and quantum effects and are in principle applicable to presently available and futur…

Carrier-Envelope Phase Controlled Electron Injection into a Laser-Wakefield Accelerator

Single cycle laser pulse propagating inside a plasma causes controllable asymmetric plasma electron expulsion from laser according to laser carrier envelope phase (CEP) and forms an oscillating plasma bubble. Bubble's transverse wakefield is modified, exhibiting periodic modulation. Injection scheme for a laser wakefield accelerator combining a single cycle low frequency laser pulse and a many cycle high frequency laser pulse is proposed. The co-propagating laser pulses form a transversely oscillating wakefield which efficiently traps and accelerates electrons from background plasma. By tuning…

Carrier-envelope phase effects in Laser Wakefield Acceleration with near-single-cycle pulses

Driving laser wakefield acceleration with extremely short, near single-cycle laser pulses is crucial to the realisation of an electron source that can operate at kHz-repetition rate while relying on modest laser energy. It is also interesting from a fundamental point of view, as the ponderomotive approximation is no longer valid for such short pulses. Through particle-in-cell simulations, we show how the plasma response becomes asymmetric in the plane of laser polarization, and dependent on the carrier-envelope phase (CEP) of the laser pulse. For the case of self-injection, this in turn strong…

激光尾场加速中源于亚周期电离注入的能量聚束

Energy Bunching from Sub-Cycle Ionization Injection in Laser Wakefield Acceleration

本文首次实验观测到激光尾场加速中由载波包络相位驱动的能量聚束，利用少周期多太瓦激光在氦氮混合气体中电离注入产生多准单能峰，揭示了亚周期电离注入实现阿秒级控制与束流结构化的潜力。

Polarization dependent beam pointing jitter in laser wake field accelerators

We present experimental results, which show a laser polarization dependent contribution to electron beam pointing jitter in laser wakefield accelerators (LWFA). We develop a theoretical model for the polarization dependence in terms of the transverse dynamics of trapped electrons, resonantly driven by bubble centroid oscillations. The latter are generated by the carrier wave phase evolution at the self-steepened laser pulse front. In the model, the polarization dependent jitter originates from shot-to-shot fluctuations of the laser carrier envelope phase. The model is verified by particle in c…