Improved evanescent-wave quartz-enhanced photoacoustic CO sensor using an optical fiber taper

Zhili Li, Zhen Wang, Yun Qi, Wei Jin, Wei Ren

Research output: Journal article publicationJournal articleAcademic researchpeer-review

36 Citations (Scopus)


An evanescent-wave quartz-enhanced photoacoustic spectroscopy (EW-QEPAS) CO sensor was developed using a tapered fiber integrated with the quartz tuning fork (QTF) and micro-resonator (mR) tubes. The fiber taper was inserted through the two mR tubes with the taper waist located between the QTF prongs. A fiber-coupled continuous-wave distributed feedback (DFB) laser at 2.3 μm was connected with the fiber taper fabricated by the flame-brushing method. The fiber taper has negligible influence on the resonant frequency and Q-factor of the QTF, but significantly reduces the background noise compared with the recently developed fiber tip-based EW-QEPAS sensor. In the EW-QEPAS detection with wavelength modulation spectroscopy, we investigated the optimal modulation depth and gas pressure, which are different from that of the conventional free-space QEPAS detection. The current CO sensor achieved a minimum detection limit of ∼20 ppm at the 210-s averaging time, corresponding to a normalized noise equivalent absorption (NNEA) coefficient of 1.44 × 10−8 cm−1 W/√Hz.
Original languageEnglish
Pages (from-to)1023-1028
Number of pages6
JournalSensors and Actuators, B: Chemical
Publication statusPublished - 1 Jan 2017


  • CO detection
  • Evanescent-wave absorption
  • Fiber taper
  • Quartz-enhanced photoacoustic spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry


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