Pulsed THz radiation due to phonon-polariton effect in [110] ZnTe crystal

TL;DR

This paper investigates the generation of long damped oscillation tails in pulsed THz radiation from [110] ZnTe crystals, linking experimental observations with theoretical modeling of phonon-polariton effects.

Contribution

It demonstrates the conditions for generating long damped oscillation tails in THz radiation and provides a theoretical framework aligning with experimental results.

Findings

LDOT duration depends on optical pulse parameters

Higher and narrower frequency peaks observed in Fourier spectra

Theoretical calculations agree with experimental waveforms

Abstract

Pulsed terahertz (THz) radiation, generated through optical rectification (OR) by exciting [110] ZnTe crystal with ultrafast optical pulses, typically consists of only a few cycles of electromagnetic field oscillations with a duration about a couple of picoseconds. However, it is possible, under appropriate conditions, to generate a long damped oscillation tail (LDOT) following the main cycles. The LDOT can last tens of picoseconds and its Fourier transform shows a higher and narrower frequency peak than that of the main pulse. We have demonstrated that the generation of the LDOT depends on both the duration of the optical pulse and its central wavelength. Furthermore, we have also performed theoretical calculations based upon the OR effect coupled with the phonon-polariton mode of ZnTe and obtained theoretical THz waveforms in good agreement with our experimental observation.