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Title: Bichromatic random laser from a powder of rhodamine-doped sub-micrometer silica particles

We studied the random laser (RL) bichromatic emission (BCE) from a powder consisting of silica particles infiltrated with Rhodamine 640 (Rh640) molecules. The BCE is attributed to Rh640 monomers and dimers. Because of the efficient monomer-dimer energy transfer, we observed RL wavelength switching from ≈ 620 nm to ≈650 nm and the control of the emitted wavelength was made by changing only the excitation laser intensity. None of external parameters such as excitation laser spot size or radiation detector position was changed as in previous experiments. Two laser thresholds associated either to monomers or dimers were clearly observed. Moreover, an effect analog to frequency-pulling among two coupled oscillators was identified measuring the RL spectra as a function of the excitation laser intensity. A wavelength shift, Δλ, was measured between the monomer and dimer resonance wavelengths, changing only the excitation laser intensity. The maximum value of Δλ ≈ 16 cm{sup −1} was obtained for laser pulses of 7 ns with 30 μJ.
Authors:
;  [1] ;  [2] ;  [3]
  1. Programa de Pós-Graduação em Ciências de Materiais, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil)
  2. Department of Chemistry, University of Victoria, V8P 5C2 Victoria (Canada)
  3. Departamento de Física, Universidade Federal de Pernambuco, Recife 50670-901 (Brazil)
Publication Date:
OSTI Identifier:
22275624
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DIMERS; DOPED MATERIALS; EMISSION SPECTRA; ENERGY TRANSFER; EXCITATION; MOLECULES; MONOMERS; OSCILLATORS; PARTICLE SIZE; PARTICLES; PHOTON EMISSION; POWDERS; RANDOMNESS; RESONANCE; SILICA; SOLID STATE LASERS