Temperature independent refractive index measurement using a fiber Bragg grating on abrupt tapered tip

• Type: Article in International Scientific Journal
• Date: 2018

Authors

Gomes, AD (Author) Other; Silveira, B (Author) Other; Warren Smith, SC (Author) Other; Becker, M (Author) Other; Rothhardt, M (Author) Other; Frazao, O (Author) FCUP

Journal

Title: Optics and Laser Technology

Vol. 101

Pages: 227-231

ISSN: 0030-3992

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 11 Citations

Scopus - 11 Citations

Other information

Authenticus ID: P-00N-8M0

DOI: 10.1016/j.optlastec.2017.11.031

Abstract (EN): A fiber Bragg grating was inscribed in an abrupt fiber taper using a femtosecond laser and phase-mask interferometer. The abrupt taper transition allows to excite a broad range of guided modes with different effective refractive indices that are reflected at different wavelengths according to Bragg's law. The multimode-Bragg reflection expands over 30 nm in the telecom-C-band. This corresponds to a mode field overlap of up to 30% outside of the fiber, making the device suitable for evanescent field sensing. Refractive index and temperature measurements are performed for different reflection peaks. Temperature independent refractive index measurements are achieved by considering the difference between the wavelength shifts of two measured reflection peaks. A minimum refractive index sensitivity of 16 +/- 1 nm/RlU was obtained in a low refractive index regime (1.3475-1.3720) with low influence of temperature (-0.32 0.06 pm/degrees C). The cross sensitivity for this structure is 2.0 x 10(-5) RlU/degrees C.. The potential for simultaneous measurement of refractive index and temperature is also studied.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5