Photon Echo from Localized Excitons in Semiconductor Nanostructures

Abstract

An overview on photon echo spectroscopy under resonant excitation of the exciton complexes in semiconductor nanostructures is presented. The use of four-wavemixing technique with the pulsed excitation and heterodyne detection allowed us to measure the coherent response of the system with the picosecond time resolution. It is shown that, for resonant selective pulsed excitation of the localized exciton complexes, the coherent signal is represented by the photon echoes due to the inhomogeneous broadening of the optical transitions. In case of resonant excitation of the trions or donor-bound excitons, the Zeeman splitting of the resident electron ground state levels under the applied transverse magnetic field results in quantum beats of photon echo amplitude at the Larmor precession frequency. Application of magnetic field makes it possible to transfer coherently the optical excitation into the spin ensemble of the resident electrons and to observe a long-lived photon echo signal. The described technique can be used as a high-resolution spectroscopy of the energy splittings in the ground state of the system. Next, we consider the Rabi oscillations and their damping under excitation with intensive optical pulses for the excitons complexes with a different degree of localization. It is shown that damping of the echo signal with increase of the excitation pulse intensity is strongly manifested for excitons, while on trions and donor-bound excitons this effect is substantially weaker.

Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots

“…The H-component of the signal was detected along the 2k 2 -k 1 direction. The FWM signal was overlapped with the reference pulse and the resulting interference signal was heterodyne detected at the balanced photoreceiver 41 . The delay line of the reference pulse t ref was scanned relative to the first pulse to obtain the temporal profile of the electric field amplitude of the FWM signal.…”

Extending the time of coherent optical response in ensemble of singly-charged InGaAs quantum dots

“…The pulse energy of P = 5 pJ corresponds to the pulse area of about π. The resulting transient four-wave mixing (FWM) signal is detected in reflection geometry in the direction of k S = 2k 2 − k 1 using heterodyne detection [2,18]. The time-resolved electric field amplitude of the FWM signal is shown in Fig 1(c) by the blue line for τ 12 = 33.3 ps and τ 23 = 100 ps, where τ ij is the time delay between pulses i and j in the sequence.…”

“…One of the solutions is to use the spin degrees of freedom of resident electrons in semiconductors which makes it possible to extend the timescale of coherent optical response by several orders of magnitude [15,17]. The demonstration of this concept has been achieved for localized charged excitons in CdTe/(Cd,Mg)Te quantum well structures and donor-bound excitons in bulk ZnO crystals [18]. It is based on resonant excitation of the donor bound exciton D 0 X or negatively charged exciton (trion) X − with a sequence of three resonant optical pulses in the presence of a transverse magnetic field [15].…”

Photon echo polarimetry of excitons and biexcitons in a CH$_3$NH$_3$PbI$_3$ perovskite single crystal

“…Note, χ (3) has maxima around resonance frequencies as well as susceptibilities of other orders χ (1) , χ (2) , etc. 46 In our experiment this response is measured using heterodyne detection [47][48][49] where the recorded signal, I PD , is given by the interference between the measured light and a strong reference beam on the photodiode. By changing the reference pulse arrival time, τ ref , we measure the dynamics of the FWM signals.…”