Mechanical oscillations in lasing microspheres
Toncelli, Alessandra (Università di Pisa)
Capuj, Nestor Eduardo (Universidad de La Laguna)
Garrido Fernández, Blas (Universitat de Barcelona. Departament d'Electrònica)
Sledzinska, Marianna (Institut Català de Nanociència i Nanotecnologia)
Sotomayor Torres, Clivia M. (Institut Català de Nanociència i Nanotecnologia)
Tredicucci, Alessandro (Università di Pisa)
Navarro Urrios, Daniel (Institut Català de Nanociència i Nanotecnologia)

Date:	2017
Abstract:	We investigate the feasibility of activating coherent mechanical oscillations in lasing microspheres by modulating the laser emission at a mechanical eigenfrequency. To this aim, 1. 5%Nd3+:Barium- Titanium-Silicate microspheres with diameters around 50 lm were used as high quality factor (Q>106) whispering gallery mode lasing cavities. We have implemented a pump-and-probe technique in which the pump laser used to excite the Nd3+ ions is focused on a single microsphere with a microscope objective and a probe laser excites a specific optical mode with the evanescent field of a tapered fibre. The studied microspheres show monomode and multi-mode lasing action, which can be modulated in the best case up to 10 MHz. We have optically transduced thermally activated mechanical eigenmodes appearing in the 50-70MHz range, the frequency of which decreases with increasing the size of the microspheres. In a pump-and-probe configuration, we observed modulation of the probe signal up to the maximum pump modulation frequency of our experimental setup, i. e. , 20 MHz. This modulation decreases with frequency and is unrelated to lasing emission, pump scattering, or thermal effects. We associate this effect to free-carrier-dispersion induced by multiphoton pump light absorption. On the other hand, we conclude that, in our current experimental conditions, it was not possible to resonantly excite the mechanical modes. Finally, we discuss on how to overcome these limitations by increasing the modulation frequency of the lasing emission and decreasing the frequency of the mechanical eigenmodes displaying a strong degree of optomechanical coupling.
Grants:	Ministerio de Economía y Competitividad RYC-2014-15392 European Commission 713450 European Commission 321122 Ministerio de Economía y Competitividad FIS2015-70862-P
Rights:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Experimental conditions ; High quality factors ; Mechanical oscillations ; Microscope objective ; Modulation frequencies ; Pump-and-probe technique ; Thermally activated ; Whispering-gallery-mode lasing
Published in:	Journal of applied physics, Vol. 122, Núm. 5 (August 2017) , article 053101, ISSN 1089-7550

DOI: 10.1063/1.4997182

Post-print 18 p, 891.2 KB

Data content 1 p, 173.9 KB

zip File Data Files 22.8 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles