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Optics Letters

Optics Letters


  • Vol. 27, Iss. 9 — May. 1, 2002
  • pp: 689–691

Prism-coupled multimode waveguide refractometer

Zhi-Mei Qi, Naoki Matsuda, Jose H. Santos, Akiko Takatsu, and Kenji Kato  »View Author Affiliations

Optics Letters, Vol. 27, Issue 9, pp. 689-691 (2002)

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A new refractometer has been developed based on changes in the effective refractive index (RI) of the highest-order TE (or TM) mode in a prism-coupled multimode planar waveguide induced by interaction between an evanescent field and a liquid sample. The waveguide was a 100-mu;m -thick quartz plate fixed on a poly(methyl methacrylate) support containing a flow cell. A pair of prism couplers contacted the quartz plate in the flow-cell region. Such an optical sensor can detect the RI of liquid in a wide range by monitoring the resonant angle of the highest-order mode that changes order number with changes in the sample's RI. When a highest-order mode corresponding to a given RI range is used as the sensor probe, a slight RI change in this range can be detected by measurement of the output light intensity. With this method the sensor was demonstrated to have a resolution of 3×10-5 for the RI of an aqueous solution. Combining this result with theoretical calculation indicates that the sensor can detect a 0.5-nm-thick monolayer adsorbed from an aqueous solution. Therefore, the sensor is suitable for real-time detection of biomolecular interactions.

© 2002 Optical Society of America

OCIS Codes
(130.6010) Integrated optics : Sensors
(160.2750) Materials : Glass and other amorphous materials
(220.4830) Optical design and fabrication : Systems design
(230.7400) Optical devices : Waveguides, slab
(240.6700) Optics at surfaces : Surfaces
(290.3030) Scattering : Index measurements

Zhi-Mei Qi, Naoki Matsuda, Jose H. Santos, Akiko Takatsu, and Kenji Kato, "Prism-coupled multimode waveguide refractometer," Opt. Lett. 27, 689-691 (2002)

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  4. A. Klotz, C. Barzen, A. Brecht, R. D. Harris, G. R. Quigley, J. S. Wilkinson, and G. Gauglitz, Proc. SPIE 3620, 345 (1999).

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