Ionic solvent assisted MAPbBr3 perovskite film for two-photon pumped single mode laser

The morphology images of the samples were collected on a ZEISS Auriga SEM. The crystal phases data were acquired on a power X-ray diffractometer (PXRD, Rigaku D/MAX2500PC) with Cu Kα radiation. The absorption was adopted by a Scan UV-vis spectrophotometer (UV-vis: UV-2100, Shimadzu, Japan) at room temperature ranging from 200 to 800 nm. The PL spectra were measured by a fluorescence spectrophotometer (PL: Agilent Cary Eclipse, Australia). For temperature dependent PL experiment, the samples were placed into an optical cryostat with an adjustable temperature range from 4 to 300 K (OptistatDry TLEX, Oxford). The 405 nm continuous wave laser was applied as excitation source and the PL signals were collected by a fiber spectrometer (Ocean optics) with a spectral resolution of 1 nm. A commercial Ti: sapphire regenerative amplifier (800 nm, 35 fs, 1 kHz) was employed as the pumping source during the ASE and lasing experiments. For the ASE experiments, the excitation beam was focused onto samples through a cylindrical lens, and the stripe length of the spot size was controlled by an adjustable slit with a length of 3 mm and a width of 120 μm. The emission signals were acquired by a fiber spectrometer (Ocean Optics) with a spectral resolution of 1 nm. For modal gain measurements, the stripe length was variable from 0 to 0.3 mm. For lasing experiments, the excitation beam was introduced to a confocal system (WITec alpha300 R) and focused onto the samples through an objective (10×). The PL signals were collected by the same objective into a spectrograph with 600 mm−1 grating and a silicon-charged coupled of resolution of 0.08 nm. The TRPL of the samples was detected via a streak camera system (5200, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences). The ultrafast TA of the samples were measured through a Helios pump-probe system (Ultrafast system LLC).