Real-time ultrafast oscilloscope with a relativistic electron bunch train

In Hyung Baek,Fabian Rotermund,Kitae Lee,Young Uk Jeong,Young Chan Kim,Hyun Woo Kim,Mihye Kim,Sunjeong Park,Kyu-Ha Jang,Junho Shin,Nikolay A Vinokurov,Hyeon Sang Bark,Key Young Oang

doi:10.1038/s41467-021-27256-x

Abstract

The deflection of charged particles is an intuitive way to visualize an electromagnetic oscillation of coherent light. Here, we present a real-time ultrafast oscilloscope for time-frozen visualization of a terahertz (THz) optical wave by probing light-driven motion of relativistic electrons. We found the unique condition of subwavelength metal slit waveguide for preserving the distortion-free optical waveform during its propagation. Momentary stamping of the wave, transversely travelling inside a metal slit, on an ultrashort wide electron bunch enables the single-shot recording of an ultrafast optical waveform. As a proof-of-concept experiment, we successfully demonstrated to capture the entire field oscillation of a THz pulse with a sampling rate of 75.7 TS/s. Owing to the use of transversely-wide and longitudinally-short electron bunch and transversely travelling wave, the proposed “single-shot oscilloscope” will open up new avenue for developing the real-time petahertz (PHz) metrology.

Highlights

The deflection of charged particles is an intuitive way to visualize an electromagnetic oscillation of coherent light
We take a fresh approach to the real-time oscilloscope via momentary stamping of a traveling optical wave on a quasi-onedimensional (Q-1D) array of relativistic (MeV) electrons whose velocity is close to the speed of light
We propose a concept that overturns the conventional streaking technique, i.e., measuring the instant longitudinal dependence of the electric field of a light wave by using an ultrashort relativistic electron bunch, and present a proof-of-concept experiment with optical wave packets oscillating at THz frequency

Summary

Introduction

The deflection of charged particles is an intuitive way to visualize an electromagnetic oscillation of coherent light. Temporal imaging with a time lens has emerged as a method for single-shot acquisition of optical waveform[5,6,7], but its temporal accuracy should be further improved for broader use In such nonlinear optical (NLO) conversion techniques for assessing broadband light waves[8], the reconstructed field distribution is prone to be distorted from the original waveform due to imperfect phase-matching features inside NLO materials during frequency conversion processes[9,10,11]. We propose a concept that overturns the conventional streaking technique, i.e., measuring the instant longitudinal dependence of the electric field of a light wave by using an ultrashort relativistic electron bunch, and present a proof-of-concept experiment with optical wave packets oscillating at THz frequency

Methods

Results

Conclusion