Waveform-Controlled Terahertz Radiation from the Air Filament Produced by Few-Cycle Laser Pulses

TL;DR

This paper presents a new method to generate waveform-controlled terahertz radiation from air plasma using few-cycle laser pulses, with control achieved through filament length and laser CEP, supported by theoretical modeling.

Contribution

The study introduces a novel scheme for controlling THz waveforms via filamentation of CEP-stabilized few-cycle laser pulses in air, combining experimental results with theoretical analysis.

Findings

THz waveform can be controlled by filament length and laser CEP

Experimental results align with photocurrent model calculations

Phase shifts in filament are explained by propagation effects

Abstract

Waveform-controlled Terahertz (THz) radiation is of great importance due to its potential application in THz sensing and coherent control of quantum systems. We demonstrated a novel scheme to generate waveform-controlled THz radiation from air plasma produced when carrier-envelope-phase (CEP) stabilized few-cycle laser pulses undergo filamentation in ambient air. We launched CEP-stabilized 10 fs-long (~ 1.7 optical cycles) laser pulses at 1.8 {\mu}m into air and found that the generated THz waveform can be controlled by varying the filament length and the CEP of driving laser pulses. Calculations using the photocurrent model and including the propagation effects well reproduce the experimental results, and the origins of various phase shifts in the filament are elucidated.