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Whispering gallery modes excitation in borosilicate glass microspheres by K+ ion-exchanged channel waveguide coupler

Whispering gallery modes excitation in borosilicate glass microspheres by K+ ion-exchanged channel waveguide coupler
Whispering gallery modes excitation in borosilicate glass microspheres by K+ ion-exchanged channel waveguide coupler
Optical microsphere resonators, with their exceptionally low optical losses and high Q-factors, are attracting a lot of interest in integrated optics and related fields. Not being accessible by free-space beams, whispering gallery modes (WGM) of a microsphere resonator require near-field coupler devices. Efficient evanescent coupling has been demonstrated previously by using thin tapered fibres, fibre half-block couplers, angle-polished fibres and bulk prisms. In this work, we demonstrate WGM excitation in microspheres, from 8 to 15 µm in diameter, by using an integrated optics channel waveguide. Light from a tunable laser was coupled into a single mode K+ ion-exchanged channel waveguide formed in BK7 glass substrate. Dry borosilicate glass microspheres were dispersed on the substrate surface. Polystyrene microspheres were suspended in electrolyte water solution and confined in a closed cell on top of the waveguide. The light was coupled to the particles sitting on the waveguide surface. The scattered light was observed through the microscope. As the laser wavelength was tuned, the observed images were recorded with a CCD camera. WGM excitation was observed through the increased scattered light intensity at certain wavelengths. In the case of glass microspheres and a Ti:Sapphire tunable laser, the obtained resonance quality (Q-) factors were about 400. The resonances observed in polystyrene microspheres using a tunable diode laser had lower Q-factors and were deteriorating with decreasing particle size.
9780819461438
Grujic, Katarina
c9936e03-f933-4a9a-99b4-d8a10175b1c3
Hole, J.Patrick
2f40307b-c893-4e55-9885-1c08b8119d0b
Hellesø, Olav Gaute
7c341b6b-c11d-475d-aedd-558f02210e53
Wilkinson, James S.
73483cf3-d9f2-4688-9b09-1c84257884ca
Grujic, Katarina
c9936e03-f933-4a9a-99b4-d8a10175b1c3
Hole, J.Patrick
2f40307b-c893-4e55-9885-1c08b8119d0b
Hellesø, Olav Gaute
7c341b6b-c11d-475d-aedd-558f02210e53
Wilkinson, James S.
73483cf3-d9f2-4688-9b09-1c84257884ca

Grujic, Katarina, Hole, J.Patrick, Hellesø, Olav Gaute and Wilkinson, James S. (2006) Whispering gallery modes excitation in borosilicate glass microspheres by K+ ion-exchanged channel waveguide coupler. SPIE : Photonics West: 8th International Conference on Laser Beam Control and Applications, San José, Costa Rica. 22 - 26 Jan 2006. (doi:10.1117/12.669565).

Record type: Conference or Workshop Item (Paper)

Abstract

Optical microsphere resonators, with their exceptionally low optical losses and high Q-factors, are attracting a lot of interest in integrated optics and related fields. Not being accessible by free-space beams, whispering gallery modes (WGM) of a microsphere resonator require near-field coupler devices. Efficient evanescent coupling has been demonstrated previously by using thin tapered fibres, fibre half-block couplers, angle-polished fibres and bulk prisms. In this work, we demonstrate WGM excitation in microspheres, from 8 to 15 µm in diameter, by using an integrated optics channel waveguide. Light from a tunable laser was coupled into a single mode K+ ion-exchanged channel waveguide formed in BK7 glass substrate. Dry borosilicate glass microspheres were dispersed on the substrate surface. Polystyrene microspheres were suspended in electrolyte water solution and confined in a closed cell on top of the waveguide. The light was coupled to the particles sitting on the waveguide surface. The scattered light was observed through the microscope. As the laser wavelength was tuned, the observed images were recorded with a CCD camera. WGM excitation was observed through the increased scattered light intensity at certain wavelengths. In the case of glass microspheres and a Ti:Sapphire tunable laser, the obtained resonance quality (Q-) factors were about 400. The resonances observed in polystyrene microspheres using a tunable diode laser had lower Q-factors and were deteriorating with decreasing particle size.

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More information

e-pub ahead of print date: 2006
Venue - Dates: SPIE : Photonics West: 8th International Conference on Laser Beam Control and Applications, San José, Costa Rica, 2006-01-22 - 2006-01-26

Identifiers

Local EPrints ID: 70931
URI: http://eprints.soton.ac.uk/id/eprint/70931
ISBN: 9780819461438
PURE UUID: 2b92815d-42d5-4452-a616-61b920e07b53
ORCID for James S. Wilkinson: ORCID iD orcid.org/0000-0003-4712-1697

Catalogue record

Date deposited: 11 Dec 2009
Last modified: 02 Jul 2021 01:33

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Contributors

Author: Katarina Grujic
Author: J.Patrick Hole
Author: Olav Gaute Hellesø

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