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Two-photon-pumped amplified spontaneous emission (ASE) of CH3NH3PbBr3 microdisks (MDs) were investigated by using femtosecond laser system. Low threshold at 2.2 mJ cm(-2) was obtained. Also, emission spectral tunability from 500 to 570 nm was demonstrated by synthesis the mixed halide perovskite MDs. The spatial effect of photoluminescence (PL) properties under one-photon and two-photon excitation were also studied by means of two-photon laser scanning microscope (TPLSM) and time-resolved PL spectroscopy. It was found that the band to band emission of near-surface regions and photocarriers' diffusion from near-surface regions to interior regions is significant for one-photon excitation. By contrast, reabsorption of emission under two-photon excitation plays a major role in the emission properties of the MDs. These results will give a more comprehensive understanding of the nonlinear effect of CH3NH3PbBr3 single crystals.
Yang et al. (Fri,) studied this question.