Fig. 5: Deep-UV lasing in microresonator incorporated DU nanoparticles.
From: Ultralarge anti-Stokes lasing through tandem upconversion
a Schematic setup of the microtoroidal resonator platform for upconversion lasing. b Simulation of the excited WGMs (given in 2D cross-sectional geometry) on the surface of the microcavity with a diameter of 4 µm and ring width of 0.2 µm, respectively. c SEM image of a typical UCNPs-doped microresonator. d The transmission spectrum of a UCNPs-doped microresonator, revealing a Q-factor of around 2 × 105. Inset: schematic of the measurement setup (left) and top-view photograph of the system under measurement (right). e Emission spectra of a microresonator with Dm = 17 μm at different excitation powers. f Logarithmic plot of output intensity versus excitation power for the microresonator. g Lasing spectra of microresonators with different Dm. h Plots of measured mode spacing (Δλ) and threshold pump power (Pth) of the microresonator as a function of Dm. Data points for threshold pump powers represent mean ± standard deviation (SD, n = 3). Error bars indicate SD.
