Diode-pumped, stimulated random emission using a powder of Nd:YVO4
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2010
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INTERNATIONAL LASER PHYSICS WORKSHO, 19th
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In random lasers, which refer to lasing in disordered media, strong multiple scattering plays a constructive
role instead of being only a loss factor [1]. Random lasers have received considerable attention for several years
due to its unique properties and its potential applications. Being demonstrated in a wide variety of media,
including powders of rare-earth crystals, pulsed and continuous-wave lasing emission has been reported [2].
In this work, emission intensity and linewidth narrowing is experimentally analyzed in an optical pumped
random media, observing a sharp threshold and pulsed emission on only one transition, namely, the 4
F3/2→4
I11/2.
The powder was obtained by grinding a 1.4mol% Nd3+:YVO4 laser crystal using an agate mortar and a
pestle. The mean diameter of the particles was 390 nm (determined by laser diffraction technique). A sample
with flat surfaces and dimension of Ф5x1 mm3 was obtained by compressing ~33.7 mg of powder with a manual
punch tablet.
For the experiment, a QCW laser diode bar was used as the pump source, tuned to the maximum of the Nd3+
absorption for this sample (809 nm) with 100 µs pulse width and 3 Hz of repetition rate. The excitation beam
was focused to a square shape with area of 5.33 mm2
. The samples’ backscattered luminescence, caused by the
normal incidence beam from the diode bar, was separated from the pump excitation by a beam splitter, then
collected and analyzed using a fast oscilloscope and a spectrometer.
At low pump intensity (0.81 mW/mm2
), several fluorescent emissions from 4G7/2→4
I9/2,
4G5/2→4
I9/2,
4
F3/2→4
I9/2, and 4
F3/2→4
I11/2 Nd3+ transitions were visible, as seen in Figure a. However, by increasing the pump
intensity gradually, a threshold value is observed, accompanied by a sharp emission line at the 4
F3/2→4
I11/2
transition (1064.12 nm). Figure b shows the exponential growth for this transition, demonstrating that
stimulated random emission for this sample has been obtained. Other fluorescent emissions suffered a spectral
quenching. The spectral width of this transition decreased as a function of pump power, from 1.30 nm to 0.48
nm (Figure c).
At higher duty cycles or longer pulses (400 µs pulse width and 30 Hz of repetition rate), a spectral
broadening of the 4
F3/2→4
I11/2 transition with increased pump power is observed. This broadening is related to
thermal effects that are more significant in a powder than in bulk crystal, on account of the poor thermal
conductivity of the inhomogeneous structure. This temperature dependence is relatively strong for samples with
a narrow gain spectrum, like the Nd3+:YVO4 and much smaller in systems with broad gain spectra, such as ZnO
powder [3].
Como referenciar
VIEIRA, R.J.R.; WETTER, N.U. Diode-pumped, stimulated random emission using a powder of Nd:YVO4. In: INTERNATIONAL LASER PHYSICS WORKSHO, 19th, July 5-9, 2010, Foz do Iguacu, PR. Abstract... Disponível em: http://repositorio.ipen.br/handle/123456789/19198. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.