Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy

Li Li, Graham Thursby, George Stewart, Norhana Arsad, Deepak Uttamchandani, Brian Culshaw, Yiding Wang

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

3 Citations (Scopus)

Abstract

A novel and direct absorption line recovery technique based on tunable diode laser spectroscopy with intensity modulation is presented. Photoacoustic spectroscopy is applied for high sensitivity, zero background and efficient acoustic enhancement at a low modulation frequency. A micro-electromechanical systems (MEMS) mirror driven by an electrothermal actuator is used for generating laser intensity modulation (without wavelength modulation) through the external reflection. The MEMS mirror with 10μm thick structure material layer and 100nm thick gold coating is formed as a circular mirror of 2mm diameter attached to an electrothermal actuator and is fabricated on a chip that is wire-bonded and placed on a PCB holder. Low modulation frequency is adopted (since the resonant frequencies of the photoacoustic gas cell and the electrothermal actuator are different) and intrinsic high signal amplitude characteristics in low frequency region achieved from measured frequency responses for the MEMS mirror and the gas cell. Based on the property of photoacoustic spectroscopy and Beer's law that detectable sensitivity is a function of input laser intensity in the case of constant gas concentration and laser path length, a Keopsys erbium doped fibre amplifier (EDFA) with opto-communication C band and high output power up to 1W is chosen to increase the laser power. High modulation depth is achieved through adjusting the MEMS mirror's reflection position and driving voltage. In order to scan through the target gas absorption line, the temperature swept method is adopted for the tunable distributed feed-back (DFB) diode laser working at 1535nm that accesses the near-infrared vibration-rotation spectrum of acetylene. The profile of acetylene P17 absorption line at 1535.39nm is recovered ideally for ∼100 parts-per-million (ppm) acetylene balanced by nitrogen. The experimental signal to noise ratio (SNR) of absorption line recovery for 500mW laser power was ∼80 and hence the detectable sensitivity is of the order of 1ppm.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Volume7726
DOIs
Publication statusPublished - 2010
Externally publishedYes
EventOptical Sensing and Detection - Brussels
Duration: 12 Apr 201015 Apr 2010

Other

OtherOptical Sensing and Detection
CityBrussels
Period12/4/1015/4/10

Fingerprint

Photoacoustic spectroscopy
Laser Spectroscopy
Acetylene
Tunable Laser
photoacoustic spectroscopy
Laser spectroscopy
Diode Laser
laser spectroscopy
acetylene
Semiconductor lasers
Spectroscopy
Mirror
Mirrors
Modulation
Micro-electro-mechanical Systems
Absorption
Recovery
recovery
diodes
microelectromechanical systems

Keywords

  • Absorption line profile recovery
  • intensity modulation
  • MEMS mirror
  • photoacoustic spectroscopy
  • tunable diode laser spectroscopy

ASJC Scopus subject areas

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

Cite this

Li, L., Thursby, G., Stewart, G., Arsad, N., Uttamchandani, D., Culshaw, B., & Wang, Y. (2010). Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 7726). [77261O] https://doi.org/10.1117/12.854075

Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy. / Li, Li; Thursby, Graham; Stewart, George; Arsad, Norhana; Uttamchandani, Deepak; Culshaw, Brian; Wang, Yiding.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 7726 2010. 77261O.

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

Li, L, Thursby, G, Stewart, G, Arsad, N, Uttamchandani, D, Culshaw, B & Wang, Y 2010, Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 7726, 77261O, Optical Sensing and Detection, Brussels, 12/4/10. https://doi.org/10.1117/12.854075
Li L, Thursby G, Stewart G, Arsad N, Uttamchandani D, Culshaw B et al. Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 7726. 2010. 77261O https://doi.org/10.1117/12.854075
Li, Li ; Thursby, Graham ; Stewart, George ; Arsad, Norhana ; Uttamchandani, Deepak ; Culshaw, Brian ; Wang, Yiding. / Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 7726 2010.
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