# Broadband terahertz emission from two-color fs-laser-induced microplasmas

## TL;DR

This study explores how two-color femtosecond laser-induced microplasmas can serve as broadband terahertz sources, with efficiency depending on focusing conditions, supported by modeling and 3D simulations.

## Contribution

It introduces a semi-analytical model and Maxwell-consistent 3D simulations to optimize terahertz emission from microplasmas based on laser parameters and focusing conditions.

## Key findings

- Microplasmas act as point-sources for broadband terahertz radiation.
- Conversion efficiency exceeds 10^{-4} at 10-μJ laser energy.
- Emission bandwidth is determined by plasma density.

## Abstract

We investigate terahertz emission from two-color fs-laser-induced microplasmas. Under strongest focusing conditions, microplasmas are shown to act as point-sources for broadband terahertz-to-far-infrared radiation, where the emission bandwidth is determined by the plasma density. Semi-analytical modeling allows us to identify scaling laws with respect to important laser parameters. In particular, we find that the optical-to-THz conversion efficiency crucially depends on the focusing conditions. We use this insight to demonstrate by means of Maxwell-consistent 3D simulations, that for only 10-$\mu$J laser energy a conversion efficiency well above $10^{-4}$ can be achieved.