An intrinsic fiber-optic single loop micro-displacement sensor

Sensors (Basel). 2012;12(1):415-28. doi: 10.3390/s120100415. Epub 2012 Jan 4.


A micro-displacement sensor consisting of a fiber-loop made with a tapered fiber is reported. The sensor operation is based on the interaction between the fundamental cladding mode propagating through the taper waist and higher order cladding modes excited when the taper is deformed to form a loop. As a result, a transmission spectrum with several notches is observed, where the notch wavelength resonances shift as a function of the loop diameter. The loop diameter is varied by the spatial displacement of one end of the fiber-loop attached to a linear translation stage. In a displacement range of 3.125 mm the maximum wavelength shift is 360.93 nm, with 0.116 nm/μm sensitivity. By using a 1,280 nm broadband low-power LED source and a single Ge-photodetector in a power transmission sensor setup, a sensitivity in the order of 2.7 nW/μm is obtained in ≈ 1 mm range. The proposed sensor is easy to implement and has a plenty of room to improve its performance.

Keywords: displacement sensor; fiber loop; fiber sensors; tapered fiber.

MeSH terms

  • Fiber Optic Technology / instrumentation*
  • Microtechnology / instrumentation*
  • Refractometry
  • Signal Processing, Computer-Assisted
  • Spectrum Analysis
  • Time Factors