Fig. 4: Burnham-Chiao ringing of UC-SF in 100Nd@Y UCNPs.
From: Ultrafast upconversion superfluorescence with a sub-2.5 ns lifetime at room temperature
UC-SF decay curves (λem = 588 nm) of 100Nd@Y UCNPs upon fs-pulsed laser excitation at 800 nm with a power of 1.4 mW and an excitation spot diameter of (a) 56.3, (b) 105.7, and (c) 163.0 μm. The insets show the microscopic UC-SF images of the UCNP assemblies at the spot. UC-SF decay curves (λem = 588 nm) of 100Nd@Y UCNPs at the condition of large emitting sample length upon 800-nm fs-pulsed laser excitation with a power density of (d) 0.44, (e) 0.52, (f) 0.63, and (g) 0.79 kW cm−2. h UC-SF decay curve (λem = 588 nm) of 100Nd@Y UCNPs upon 800-nm fs-pulsed laser excitation with a power density of 0.98 kW cm−2 and an excitation spot diameter of 247.5 μm. The enlarged curve in the inset shows two periodical oscillatory peaks with a time interval of ~40 ns.
