2022-07-01 16:36


Conference: Bucharest University Faculty of Physics 2019 Meeting

Section: Optics, Spectroscopy, Plasma and Lasers

Lasing and fluorescence emission by laser pumped droplets levitating in acoustic field

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

National Institute for Laser, Plasma and Radiation Physics, P.O.Box MG-6, RO-077125 Bucharest-Magurele, Romania


fluorescence, lasing, acoustic levitation

The fluorescence emission of a single, water-based droplet that is levitating in acoustic field, is reported. The bead is seeded with a high quantum yield laser dye, Rhodamine 6G, at several concentrations and is irradiated with a laser pulsed beam, emitted on green at 532 nm. Fluorescence amplification is obtained due to internal reflections in the droplet, which behaves as a quasispherical closed optical resonator [1,2]. Two peaks are lased that depend on solution concentration, pumping energy and resonator’s shape. The novelty of these measurements is that the size and form of the resonator can be modified, so that the lasing emission can be tuned. The droplets are levitating in a single-axis levitator which uses an array of small ultrasonic emitters, that operate at 40 Khz [3]. At this frequency, the air-borne acoustic waves have the wavelength of 8.65 mm, which allows the levitation of samples of up to ≈4 mm diameter. The analyzed droplets have volumes between 1 - 3 µl, (diameters around 1.5 mm), and they can be acoustically levitated.


1. Andrei, IR; Boni, M; Staicu, A; Pascu, ML; JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 35 (8) 1950-1955 (2018).

2. Boni, M; Staicu, A; Andrei, IR; Smarandache, A; Nastasa, V; Saponjic, Z; Pascu, ML; ROMANIAN REPORTS IN PHYSICS 70 (4) 513 (2018).

3. Asier Marzo, Adrian Barnes, and Bruce W. Drinkwater, REVIEW OF SCIENTIFIC INSTRUMENTS 88, 085105 (2017)

This work was supported by grants of the Romanian National Authority for Scientific Research and Innovation, CNCS/CCCDI-UEFISCDI, projects number PN-III-P1-1.1-PCCDI-2017-0728, within PNCDI III and the Nucleu project 16N/08.02.2019.