Reflective tilted fiber Bragg grating refractometer based on strong cladding to core recoupling


  • Guo, Tuan
  • Tam, Hwa-Yaw
  • Krug, Peter A.
  • Albert, Jacques




A novel in-fiber structure for power-referenced refractometry with the capability to measure surrounding refractive index (SRI) as low as 1.33 is proposed and demonstrated. A short optical fiber stub containing a weakly tilted Bragg grating is spliced to another fiber with a large lateral offset. The reflection from this structure occurs in two well-defined wavelength bands, the Bragg reflected core mode and the cladding modes. The cladding modes reflect different amounts of power as the SRI changes, while the core-mode reflection from the same weakly tilted FBG remains unaffected by the SRI. The power reflected in the core mode band can be used as a reliable reference to cancel out any possible power fluctuations. The proposed refractometer with improved sensitivity for low SRI measurement together with the tip-reflection sensing feature, is a good candidate for sensing in chemical and biological applications.


OSA Publishing

Peer Review: 

Published in Peer Reviewed Journal

Faculty Name: 

Faculty of Engineering and Design

Department Name: 

Department of Electronics

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