Optical gain and photo-bleaching of organic dyes, quantum dots, perovskite nanoplatelets and nanodiamonds

Optical gain and resistance against photo-bleaching are key material parameters for practical applications in microlasers and microphotonics. Here we present studies of optical amplification and photo-bleaching in a wide range of optical gain materials, including fluorescent dyes, quantum dots and rods, organic and inorganic room temperature polaritons, and nanodiamonds with emission range from 430 - 680 nm. We used amplified spontaneous emission (ASE) for each material to measure the optical gain. Robustness against photo-bleaching was determined by measuring the intensity of spontaneous emission of the material as a function of the number of excitation femtosecond pulses (10⁶-10¹⁰) at various excitation energy densities.  We show that pyrromethene laser dyes are the best organic emitters in terms of low excitation energy and good optical gain, whereas solid-state polariton materials are better in terms of high optical gain and stability. We find that all organic and inorganic optical gain materials bleach completely after 10⁶ to 10⁹ illumination pulses with typical 0.1 to 0.6 GW/cm² peak power density, with a clear exception of nanodiamonds. We show that nanodiamonds are the only optical gain material that shows no photo-bleaching beyond the 10¹⁰ excitation pulses of 300 fs pulse duration and with 0.16 GW/cm² peak power density.