Mid- and Far-Infrared Supercontinuum Generation in Bulk Tellurium Spanning from 5.3 $\mu$m to 32 $\mu$m

TL;DR

This study demonstrates supercontinuum generation in bulk tellurium using a high-power CO2 laser, producing a broad spectrum from 5.3 to 32 micrometers, highlighting tellurium's potential for nonlinear optical applications.

Contribution

The paper reports the first supercontinuum generation in bulk tellurium spanning mid- and far-infrared wavelengths, with detailed analysis of nonlinear processes and refractive index properties.

Findings

Spectrum spans from 5.3 to 32 micrometers.

Stimulated Raman scattering, self-phase modulation, and four wave mixing are key processes.

Nonlinear refractive index of tellurium is about 40 times that of GaAs.

Abstract

Supercontinuum generation is performed in the bulk semiconductor tellurium (Te) with a high-power picosecond CO$_2$ laser at peak intensities up to 20 GW/cm$^2$. The spectrum spans from the second harmonic of the pump at 5.3 $\mu$m to 32 $\mu$m. Stimulated Raman scattering along with self-phase modulation and four wave mixing are found to be the main nonlinear optical processes leading to the spectral broadening. Numerical simulations using the experimental conditions indicate that the nonlinear refractive index of Te, $n_{2,\textrm{eff}}$(Te) is about (40 $\pm$ 10) $n_{2,\textrm{eff}}$(GaAs), making this a very promising material for nonlinear optical devices.