Fiber loop ring down spectroscopy for trace chemical detection

Cengiz, Betül
Fiber loop ring down (FLRD) spectroscopy is a sensitive spectroscopic technique that is based on absorption and it is convenient for trace chemical detection. Different FLRD systems are being improved in order to increase their sensitivity. In FLRD spectroscopy, detection of a sample is done by measuring of a leaking light at each trip within an optical cavity. Intensity of leaking light has an exponential decay where it is reduced by absorption of sample and scattering of light. In this project, two FLRD set-ups at 1535 nm and 808 nm were designed. In both set-ups, optical fiber and optical fiber couplers are used to form a cavity. At 1535 nm, a FLRD set-up is constructed by utilizing a pulsed laser and used for characterization of thin films, various pure liquids and fluorescein solutions. Two different sensor regions are designed with free space collimators and ferrules for the measurement of thin films and liquids, respectively. The future endeavor of the set-up is improvement for reliability and reproducibility of the system. For visible and NIR regions, a fiber coupled laser with four colors as 642 nm, 785 nm, 808 nm and 852 nm laser is used to design of a FLRD set-up. 808 nm laser is selected to build a prototype of the FLRD system. The construction of a closed loop FLRD set-up is completed and the system is characterized. Ultimate aim in our project is to be able to do trace detection at visible and NIR regions where the chemical sensitivity is higher.


Fiber loop ring down spectrometer optical based sensor for trace chemical detection
Yolalmaz, Alim; Esentürk, Okan; Danışman, Mehmet Fatih; Hanifehpour, Farhad (2016-04-11)
Fiber loop ring down (FLRD) is a time domain multi-functional sensing, characterization, detection technique. FLRD technique is used to sense temperature, pressure, strain, biological cells, refractive index, and chemical species. FLRD has high accuracy, high selectivity, ability of remote control and rapid response. In this project, two FLRD spectrometers working at 800 nm (figure 1) and 1535 nm (figure 2) were set up for sensing different chemical analytes like C2H2, CO2, Ar, N2, DMSO, DMF, H2O, C2H6O, C3...
Utilization of fiber loop ring down technique for sensing applications
Yolalmaz, Alim; Danışman, Mehmet Fatih; Bek, Alpan; Department of Micro and Nanotechnology (2017)
Fiber loop ring down (FLRD) spectroscopy is based on multiple interaction of laser light with sample/analyte. It is evolved from cavity ring down spectrometer with addition of optical fiber. Measurement accuracy rises with multiple interactions and this enhances the minimum detection limit compared to other spectrometers using single pass interaction such as FTIR, UV-VIS spectrometer. The other advantages of this technique are its insensitivity to laser fluctuation and detector performance. In this study, t...
Gas-Screen Slotted Quartz Tube Atomic Absorption Spectrometry: A Remedy for Reducing Interference Effects of Calcium and Chromium
Gholami, M.; Yosefi, M. H.; Behkami, S.; Olyai, M. R. Talei Bavil; ARSLAN, YASİN; BAKIRDERE, Sezgin; Ataman, Osman Yavuz (2013-04-13)
A simple device for the reduction of nonspectral interferences in flame atomic absorption spectrometry is proposed. It has been reported that the use of a gas screen (GS) system together with a slotted quartz tube (SQT) enhances the residence time of analyte atoms in measurement zone even more than the SQT alone. This combination causes enhancement of sensitivity and improves the reproducibility of absorbance measurements. In addition, it protects the optical windows of the atomic absorption spectrometer. T...
Intracavity gas detection with fiber loop ring down spectroscopy
Yolalmaz, Alim; Hanifehpour Sadroud, Farhad; Danışman, Mehmet Fatih; Esentürk, Okan (Elsevier BV, 2017-8)
In this study, an easy to construct and sensitive intracavity fiber loop ring down spectrometer was built by commercially available basic components and its application on chemical sensing is presented. System performance was investigated by using various acetylene/nitrogen gas mixtures as a function of total pressure (between 25 and 65 psia) in sensing region and a calibration curve is established. The instrument can achieve a limit of detection of 0.1% without a FBG and/or EDFA or a need for a complicated...
Use of gold nanoparticle containing poly (allylamine hydrochloride)/ poly (acrylic acid) multilayer films as sers substrates
Kölemen, Birsu; Ertaş, Gülay; Erel Göktepe, İrem; Department of Chemistry (2015)
Surface-enhanced Raman spectroscopy (SERS) is a surface sensitive vibrational spectroscopy technique that results in the enhancement of Raman scattering by molecules adsorbed on rough metal surfaces. It is a powerful, sensitive and non-destructive technique which is used in chemical, material and life sciences including biosensing, catalysis, spectroelectrochemistry, criminology, single molecule SERS applications and many others. Nanoparticle (NP) embedded multilayer films using Layer by Layer (LbL) techniq...
Citation Formats
B. Cengiz, “Fiber loop ring down spectroscopy for trace chemical detection,” M.S. - Master of Science, Middle East Technical University, 2013.