Photonic crystal fiber modal interferometer for explosives detection

Chuanyi Tao, Heming Wei, Sridhar Krishnaswamy

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The detection of explosives and their residues is of great importance in public health, antiterrorism and homeland security applications. The vapor pressures of most explosive compounds are extremely low and attenuation of the available vapor is often great due to diffusion in the environment, making direct vapor detection difficult. In this paper, a photonic-microfluidic integrated sensor for highly sensitive 2,4,6-Trinitrotoluene (TNT) detection is described based on an in-fiber Mach-Zehnder interferometer (MZI) in a photonic crystal fiber (PCF). A segment of PCF is inserted between standard single-mode fibers (SMF) via butt coupling to form a modal interferometer, in which the cladding modes are excited and interfere with the fundamental core mode. Due to butt coupling, the small air gap between SMF and PCF forms a coupling region and also serves as an inlet/outlet for the gas. The sensor is fabricated by immobilizing a chemo-recognition coating on the inner surface of the holey region of the PCF, which selectively and reversibly binds TNT molecules on the sensitized surface. The sensing mechanism is based on the determination of the TNT-induced wavelength shift of interference peaks due to the refractive index change of the holey-layer. The sensor device therefore is capable of field operation.

Original languageEnglish (US)
Title of host publicationNanosensors, Biosensors, and Info-Tech Sensors and Systems 2016
EditorsVijay K. Varadan
ISBN (Electronic)9781510600430
StatePublished - 2016
EventNanosensors, Biosensors, and Info-Tech Sensors and Systems 2016 - Las Vegas, United States
Duration: Mar 21 2016Mar 24 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherNanosensors, Biosensors, and Info-Tech Sensors and Systems 2016
Country/TerritoryUnited States
CityLas Vegas


  • Explosives Detection
  • Interferometer
  • Photonic crystal fiber
  • Sensor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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