Sub-nanosecond delay of light in (Cd,Zn)Te crystal

TL;DR

This paper investigates the ultra-fast delay and propagation of light in bulk CdZnTe crystals, revealing sub-nanosecond delays, pulse stretching, and excitonic polariton dynamics through time-resolved optical techniques.

Contribution

It provides new insights into excitonic polariton relaxation and propagation in CdZnTe, demonstrating sub-nanosecond delays and detailed spectral dispersion characteristics.

Findings

Time delays up to 350 ps observed

Strong stretching of 150 fs pulses in the crystal

Excitonic polariton lifetimes of 1.5 and 3 ns

Abstract

We study excitonic polariton relaxation and propagation in bulk CdZnTe using time- resolved photoluminescence and time-of-flight techniques. Propagation of picosecond optical pulses through 0.745 mm thick crystal results in time delays up to 350 ps, depending on the photon energy. Optical pulses with 150 fs duration become strongly stretched. The spectral dependence of group velocity is consistent with the dispersion of the lower excitonic polariton branch. The lifetimes of excitonic polariton in the upper and lower branches are 1.5 and 3 ns, respectively.