Ultrafast emission under two‐photon excitation of biexcitons in CuCl quantum dots

Abstract

Time-resolved photoluminescence spectra of biexcitons confined in CuCl quantum dots have been measured by means of an optical Kerr-gate method. When the biexcitons are generated by resonant two-photon excitation, a new ultrashort photoluminescence is observed. This result indicates that the resonant twophoton excitation of the biexcitons induces a new transition process with a large optical nonlinearity which is characteristic for the direct generation.

Quantum-confined biexcitons in CuCl quantum dots and their unconventional optical properties

“…By means of ultrafast time-resolved spectroscopy with the use of an optical Kerr gate method, we found a new PL band, which emerges in an ultrashort stage only under resonant twophoton excitation conditions. Here we suggest that this PL band gives rise to the laser emission described in the previous subsection [34].…”

Superfluorescent pulsed emission from biexcitons in an ensemble of semiconductor quantum dots

“…Thus far, we have reported highly efficient laser emission from the biexciton states in CuCl QDs embedded in a NaCl matrix under two-photon excitation of the biexcitons [23,24]. Furthermore, we have observed pulsed emission from the biexcitons through time-resolved photoluminescence (PL) measurements, which suggest the possibility that the emission exhibits superfluorescence [25]. In this paper, we report the dependence of the time profiles of the PL from the biexcitons upon the excitation intensity.…”

Biexcitonic superfluorescence from CuCl quantum dots under resonant two‐photon excitation

“…We recently reported superfluorescence from biexcitons in an ensemble of CuCl QDs under resonant twophoton excitation of biexcitons [16,17]. The observed superfluorescence PL band (which we termed the FM band) clearly exhibited pulse-shaped temporal profiles and the excitation density dependence of the peak intensity was consistent with superfluorescence.…”

“…Figure 1 shows the excitation density dependence of the time-integrated PL spectra. The M band at 3.158 eV has been reported as a biexciton band [14][15][16][17][18][19]. In addition, a new PL band (denoted by FM) appeared on the higher energy side of the M band.…”