Carrier concentration dependence of optical Kerr nonlinearity in indium tin oxide films

TL;DR

This study measures how the optical Kerr nonlinearity in indium tin oxide films depends on carrier concentration and wavelength, revealing potential for tuning in ultrafast optoelectronic applications.

Contribution

It provides the first detailed analysis of carrier concentration effects on Kerr nonlinearity in ITO films using femtosecond laser techniques.

Findings

Maximum n2-value of 4.1 x 10^-5 cm^2/GW at 720 nm

Kerr nonlinearity varies with wavelength

Relaxation time of ~1 ps in ITO films

Abstract

Optical Kerr nonlinearity (n2) in n-type indium tin oxide (ITO) films coated on glass substrates has been measured using Z-scans with 200-fs laser pulses at wavelengths ranging from 720 to 780 nm. The magnitudes of the measured nonlinearity in the ITO films were found to be dependent on the carrier concentration with a maximum n2-value of 4.1 x 10-5 cm2/GW at 720-nm wavelength and an electron density of Nd = 5.8 x 1020 cm-3. The Kerr nonlinearity was also observed to be varied with the laser wavelength. By employing a femtosecond time-resolved optical Kerr effect (OKE) technique, the relaxation time of OKE in the ITO films is determined to be ~1 ps. These findings suggest that the Kerr nonlinearity in ITO can be tailored by controlling the carrier concentration, which should be highly desirable in optoelectronic devices for ultrafast all-optical switching.