Mid-infrared fiber-optic photothermal interferometry

Zhili Li, Zhen Wang, Fan Yang, Wei Jin, Wei Ren

Research output: Journal article publicationJournal articleAcademic researchpeer-review

30 Citations (Scopus)


We demonstrate mid-infrared photothermal interferometry (PTI) in a hollow-core fiber (HCF) for trace gas detection. Compared with free-space PTI, the optical intensity could be increased by orders of magnitude by confining the pump and probe lights in the hollow core. We coupled the pump light at 4.46 μm from a quantum cascade laser and the 1555.14 nm probe light into the HCF with a bore size of 200 μm. The HCF was filled with nitrous oxide (N2O) which has strong absorption at the pump wavelength. The probe light detects the N2O absorption-induced phase change in the HCF via a fiber-optic Mach–Zehnder interferometer. With a 25 cm fiber length and 6 mW of pump power, we have achieved a minimum detection limit of 0.8 ppm for N2O, corresponding to a normalized noise equivalent absorption coefficient of 4.9 × 10−7cm−1WHz−1∕2.
Original languageEnglish
Pages (from-to)3718-3721
Number of pages4
JournalOptics Letters
Issue number18
Publication statusPublished - 15 Sep 2017

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


Dive into the research topics of 'Mid-infrared fiber-optic photothermal interferometry'. Together they form a unique fingerprint.

Cite this