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Proceedings Paper

Whispering-gallery mode lasers for biosensing: a rationale for reducing the lasing threshold
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Paper Abstract

Whispering-gallery modes have been studied extensively for biosensing applications. Whilst the vast majority of work undertaken has focused on high Q factor resonators, with the main improvement being a reduction of the resonator size to improve sensitivity, we have chosen a different pathway by starting with resonators that exhibit extremely high refractive index sensitivity but low Q factor. A way forward to overcome this limitation is to introduce a gain medium and operate the resonator above its lasing threshold. This has been shown to result on average in a 5 fold increase in the Q factor. With the lasing threshold itself being dependent on the Q factor, amongst other parameters, the Q factor enhancement can be exploited to either reduce the lasing threshold or alternatively enable smaller resonators to be operated above their lasing threshold. As a demonstration we present a 10 μm diameter polystyrene microsphere lasing in aqueous solution for refractive index sensing applications, which to the best of our knowledge is the smallest polystyrene microsphere laser ever demonstrated in these conditions.

Paper Details

Date Published: 3 March 2015
PDF: 7 pages
Proc. SPIE 9343, Laser Resonators, Microresonators, and Beam Control XVII, 93431U (3 March 2015); doi: 10.1117/12.2076889
Show Author Affiliations
Alexandre François, Univ. of Adelaide (Australia)
Nicolas Riesen, The Univ. of Adelaide (Australia)
Hong Ji, Univ. of Adelaide (Australia)
Shahraam Afshar Vahid, Univ. of Adelaide (Australia)
Univ. of South Australia (Australia)
Tanya M. Monro, Univ. of Adelaide (Australia)
Univ. of South Australia (Australia)


Published in SPIE Proceedings Vol. 9343:
Laser Resonators, Microresonators, and Beam Control XVII
Alexis V. Kudryashov; Alan H. Paxton; Vladimir S. Ilchenko; Lutz Aschke; Kunihiko Washio, Editor(s)

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