Ultrafast nanometric electron sources: current status, first applications, and suitable laser sources

Abstract

Laser pulses of a femtosecond oscillator focused on a sharp metal tip allow the generation of a pulse train of electrons at the oscillator repetition rate [1–4]. The emission of electrons from the tip takes place on the femtosecond time scale. With the advent of these novel ultrafast electron sources, important experiments have been and more will be performed ([5], see [6] for an overview). We report on the status of our current experiment aiming at a deeper understanding of the emission process by analyzing the energy of the electrons emitted. We will further discuss first experimental steps towards direct laser acceleration of low energy electrons by means of a transparent double-grating structure. This structure imposes boundary conditions that allow a net momentum transfer from the laser beam onto the electrons that travel through the structure [7, 8]. Our simulations show that electrons can be accelerated from zero kinetic energy with laser light only (Fig. 1, 2). The acceleration gradient exceeds that of maximum DC acceleration (∼6 MeV/m) even in the very low energy regime. In order to maintain phase synchronicity, a self-referenced driving laser is mandatory. We will give a progress report.