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Polydispersed Powders (Nd 3+ :YVO 4 ) for Ultra Efficient Random Lasers
Author(s) -
Wetter Niklaus U.,
Giehl Julia M.,
Butzbach Felix,
Anacleto Danilo,
JiménezVillar Ernesto
Publication year - 2018
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.201700335
Subject(s) - random laser , laser , materials science , absorption (acoustics) , neodymium , optics , scattering , diffusion , mean free path , yttrium , slope efficiency , particle size , particle (ecology) , particle size distribution , fiber laser , physics , chemistry , oxide , oceanography , metallurgy , thermodynamics , geology , lasing threshold
Random lasers hold the potential for cheap, coherent light sources that can be miniaturized and molded into any shape with several other added benefits such as speckle‐free imaging; however, they require improvements specifically in terms of efficiency. This paper details for the first time a strategy for increasing the efficiency of a random laser that consists in using smaller particles, trapped between large particles to serve as absorption and gain centers whereas the large particles control mainly the light diffusion into the sample. Measurements of backscattering cone, sample absorption, reflection, and laser emission are used to determine the samples' transport mean free path, fill fractions, laser efficiency, and the average photon path lengths inside the scattering medium for backscattered pump photons. A record slope efficiency of 50% is reached by optimizing pump photon diffusion and absorption in a powder pellet composed by a polydispersed particle size distribution (smaller particles between bigger ones) from a grinded and sieved 1.33 mol% yttrium vanadate doped with neodymium crystal with mean particle size of 54 µ m.