Experimental Difficulties With LPG Sensors Operating Close to the Phase Turning Points

Carter, Richard M.; Maier, Robert R. J.; Biswas, Palas; Basumallick, Nandini; Bandyopadhyay, Somnath; Jones, Benjamin; McCulloch, Scott; Barton, James S.

doi:10.1109/jlt.2016.2593028

Cited by 9 publications

(2 citation statements)

References 25 publications

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“…Due to this, the sensitivity and the center wavelength of the DTP-LPG can be fine-tuned. However, since DTP-LPGs are highly sensitive not only to RI, but also to strain, temperature twists and bends, experimental difficulties with noise reduction arises in measurements with these gratings, which can be overcome by isolating the sensing grating from unwanted stimuli [28].…”

Section: Fine-tuning Approachesmentioning

confidence: 99%

Long-Period Gratings and Microcavity In-Line Mach Zehnder Interferometers as Highly Sensitive Optical Fiber Platforms for Bacteria Sensing

Eftimov

Janik

Koba

et al. 2020

Sensors

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Selected optical fiber sensors offer extraordinary sensitivity to changes in external refractive (RI), which make them promising for label-free biosensing. In this work the most sensitive ones, namely long-period gratings working at (DTP-LPG) and micro-cavity in-line Mach-Zehnder interferometers (µIMZI) are discussed for application in bacteria sensing. We describe their working principles and RI sensitivity when operating in water environments, which is as high as 20,000 nm/RIU (Refractive index unit) for DTP-LPGs and 27,000 nm/RIU for µIMZIs. Special attention is paid to the methods to enhance the sensitivity by etching and nano-coatings. While the DTP-LPGs offer a greater interaction length and sensitivity to changes taking place at their surface, the µIMZIs are best suited for investigations of sub-nanoliter and picoliter volumes. The capabilities of both the platforms for bacteria sensing are presented and compared for strains of Escherichia coli, lipopolysaccharide E. coli, outer membrane proteins of E. coli, and Staphylococcus aureus. While DTP-LPGs have been more explored for bacteria detection in 102–106 Colony Forming Unit (CFU)/mL for S. aureus and 103–109 CFU/mL for E. coli, the µIMZIs reached 102–108 CFU/mL for E. coli and have a potential for becoming picoliter bacteria sensors.

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Section: Fine-tuning Approachesmentioning

confidence: 99%

Long-Period Gratings and Microcavity In-Line Mach Zehnder Interferometers as Highly Sensitive Optical Fiber Platforms for Bacteria Sensing

Eftimov

Janik

Koba

et al. 2020

Sensors

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“…Based on this result, Monika Gambhir et al designed a high sensitivity SRI sensor with a detecting range from 1.3 to 1.4 [11]. Richard M Carter et al coated the LPFG with a thin Pd layer [12], which exhibited a near eight-fold increase in response to 1% hydrogen when operated near the PMTP. However, if the grating operates near the PMTP, the 3 dB bandwidth of attenuation band will reach hundreds of nanometers [13], which cause a gentle attenuation band edge and the transmittance changes slowly with the variation of SRI.…”

Section: Introductionmentioning

confidence: 99%

Simulation of novel intensity modulated cascaded coated LPFG sensor based on PMTP

Feng

Lin

et al. 2017

J. Opt.

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This paper presents a novel intensity modulated cascaded long-period fiber grating (CLPFG) sensor which is cascaded by two same coated long-period fiber gratings (LPFGs) operating at the phase-matching turning point (PMTP). The sensor combines the high sensitivity of LPFG operating at PMTP and the narrow bandwidth of interference attenuation band of CLPFG, so a higher response to small change of the surrounding refractive index (SRI) can be obtained by intensity modulation. Based on the coupled-mode theory, the grating parameters of the PMTP of a middle odd order cladding mode of a single LPFG are calculated. Then this two same LPFGs are cascaded into a CLPFG, and the optical transmission spectrum of the CLPFG is calculated by transfer matrix method. A resonant wavelength of a special interference attenuation band whose intensity has the highest response to SRI, is selected form CLPFG’s spectrum, and setting the resonant wavelength as the operating wavelength of the sensor. Furthermore, the simulation results show that the resolution of SRI of this CLPFG is available to 1.97 × 10−9 by optimizing the film optical parameters, which is about three orders of magnitude higher than coated dual-peak LPFG and cascaded LPFG sensors. It is noteworthy that the sensor is also sensitive to the refractive index of coat, so that the sensor is expected to be applied to detections of gas, PH value, humidity and so on, in the future.

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A novel dual resonance long period waveguide grating based highly sensitive refractive index sensor with reduced temperature sensitivity

Saha

Kumar

2020

Optics Communications

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Experimental Difficulties With LPG Sensors Operating Close to the Phase Turning Points

Cited by 9 publications

References 25 publications

Long-Period Gratings and Microcavity In-Line Mach Zehnder Interferometers as Highly Sensitive Optical Fiber Platforms for Bacteria Sensing

Long-Period Gratings and Microcavity In-Line Mach Zehnder Interferometers as Highly Sensitive Optical Fiber Platforms for Bacteria Sensing

Simulation of novel intensity modulated cascaded coated LPFG sensor based on PMTP

A novel dual resonance long period waveguide grating based highly sensitive refractive index sensor with reduced temperature sensitivity

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