Faculty of Physics - University of Bucharest

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FACULTY OF PHYSICS

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2024-11-22 1:49

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Conference: Bucharest University Faculty of Physics 2018 Meeting

Section: Optics, Spectroscopy, Plasma and Lasers

Title:

Lasing of optically pumped large droplets

Authors:

Mihai BONI(1,2), Ionut-Relu ANDREI(1), Angela STAICU(1), Mihail-Lucian PASCU(1,2)

^*
Affiliation:

1)National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor 409, Magurele 077125, Ilfov, Romania

2)Faculty of Physics, University of Bucharest, Str. Atomistilor 405, Magurele 077125, Ilfov, Romania

E-mail

mihai.boni@inflpr.ro

Keywords:

pendant droplets, lasing, blue shifted, fluorescence

Abstract:

Development of laser sources able to emit on more directions at milli-, micro- and nano-meter scale, as is the case of droplet laser, is required for broader and diversified applications which range from technology to biomedicine [1]. In this paper are reported results about the interaction of 532 nm pulsed laser beam with individual pendant Rhodamine 6G dye droplets of large size parameter, x ≈ 7300 [2]. By varying dye concentration and pumping energy, are obtained typical fluorescence bands detected in such cases and a narrow, instantly or gradually blue shifted band assigned to lasing effect at droplet surface. The maximum blue shift value of the lasing peak wavelength is associated with the maximum of dye fluorescence gain curve when self-absorption effects are not present. Lasing peak position is not further influenced by pumping energy or droplet diameter decrease, after lasing reaches the wavelength of gain curve peak. A narrowed, 33 nm blue shifted band assigned to lasing emission is obtained in a gradual or instant manner, function of the irradiance intensity; it shows -up besides the fluorescence band. At low pumping energies, not larger than 10 mJ, lasing emission appears with a delay with respect to fluorescence and is gradually blue shifted up to 33 nm. Above 10 mJ, starting with the first pulse, lasing band is distinctly observed in droplet emission spectra showing 33 nm blue shift. The maximum blue shift value of lasing peak wavelength is associated with the maximum of dye fluorescence gain curve previously reported in experiments where self-absorption effects are not present [3].

References:

1. D. McGloin, "Droplet lasers: a review of current progress," Rep. Prog. Phys. 80, 054402 (2017).

2. H. Azzouz, L. Alkhafadiji, S. Balslev, J. Johansson, N. A. Mortensen, S. Nilsson, and A. Kristensen, "Levitated droplet dye laser," Opt. Express 14, 4374 (2006).

3. R. F. Kubin and A. N. Fletcher, "Fluorescence quantum yields of some rhodamine dyes," J. Lumin. 27, 455–462 (1982).

Acknowledgement:

The research was funded by Ministry of Research and Innovation (CNCS/CCCDI-UEFISCDI PN-III-P2-2.1-PED-2016-0420, PN-III-P2-2.1-PED-2016-0446), NUCLEU Program (PN 1647/2016).