Enhancing terahertz generation from a two-color plasma using optical parametric amplifier waste light

TL;DR

This paper demonstrates a method to significantly enhance terahertz emission from plasma generated by a two-color laser pulse through the addition of an 800-nm pulse, achieving up to 30-fold increase in electric field strength.

Contribution

The study introduces a simple technique using residual OPA pump light to boost THz generation in plasma, supported by experimental and numerical validation.

Findings

THz electric field enhanced by up to 30 times

Enhancement depends on the powers of the two-color and 800-nm beams

Numerical photocurrent model agrees with experimental results

Abstract

We show experimentally that the terahertz (THz) emission of a plasma, generated in air by a two-color laser pulse (containing a near IR frequency and its second harmonic), can be enhanced by the addition of an 800-nm pulse. We observed enhancements of the THz electric field by a factor of up to 30. This provides a widely accessible means for researchers using optical parametric amplifiers (OPA) to increase their THz yields by simply adding the residual pump beam of the OPA to the plasma generating beam. We investigate the dependence of the THz electric field enhancement factor on the powers of the two-color beam as well as the 800-nm enhancement beam. Numerical calculations using the well-known photocurrent model are in excellent agreement with the experimental observations.