Pump-Guided Directional Amplification of Spontaneous Emission in Single-Crystal MAPbBr3

We report directional amplified spontaneous emission (ASE) in a MAPbBr3 single crystal, which is produced by a single-pass excitation of femtosecond pulses at 560 nm and propagates coaxially with the pump beam during amplification interactions. The chirp in the pump pulses induces a delayed interaction between the photoluminescence (PL) produced by the shorter wavelength components and the excitation by the longer wavelength components, forming a “chasing–overlapping–leaving” process. The group velocity dispersion performance on the falling edge of the absorption spectrum of the MAPbBr3 crystal favors a large extension of the interaction length, facilitating such an ASE process along the pumping channel. The ASE interactions produce a yellow beam with a peak wavelength of 575 nm and a pulse energy of 0.47 nJ for a pump pulse energy of 1.2 μJ. The output ASE beam has the same quality as the pump in the small divergence and high-quality transverse mode.