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Investigation of an in-line fiber Mach–Zehnder interferometer based on peanut-shape structure for refractive index sensing
摘要： An in-line fiber Mach–Zehnder interferometer (MZI) for refractive index (RI) sensing was proposed, and the interferometer was fabricated by cascading two peanut-shape structures in the single mode fiber using the commercial fusion splicer. A model of the peanut-shape profile was used to calculate the power distribution of the modes in the device. The RI sensing performances of the peanut-shape structure in-line fiber MZIs with two different arm length (30 and 100 mm) were investigated. As the sensor with a short arm length of 30 mm, the RI sensitivity of ?67.355 nm/RIU was achieved for the RI range of 1.33–1.37. As the sensor with a long arm length of 100 mm, the simultaneous RI and temperature measurement was realized to eliminate the temperature and RI cross sensitivity, and the highest RI and temperature sensitivities of ?67.953 nm/RIU and 0.073 nm/?C were obtained, respectively.
关键词： Simultaneous refractive index and temperature measurement,Optical fiber sensor,Refractive index measurement,Mach–Zehnder interferometer,Peanut-shape structure
更新于2025-09-23 15:23:52
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Study of a large lateral core-offset in-line fiber modal interferometer for refractive index sensing
摘要： A large lateral core-offset in-line fiber modal interferometer was proposed in order to avoid the relative direction of the two core-offset joints affecting the interference performance. The RI sensing performances of the interferometers with different arm lengths were evaluated and compared with the small core-offset ones. The simulation and experimental results showed that the power remaining in the core mode decreased from 25 to 0.002% after the input light passing through the first core-offset joint as the core-offset displacement increased from 6 to 40 μm. Thus, the interference between the core mode and cladding mode within the enlarged core-offset interferometer was suppressed, and meanwhile the interference within the cladding modes was dominated. As the core-offset displacement was simply enlarged from 6 to 40 μm, the RI sensitivity was greatly improved from 43.97 to 123.40 nm/RIU. The proposed sensor is a cost-effective solution for RI sensing purpose, and exhibits the advantages of high sensitivity, simple structure and easy fabrication with only a fusion splicer.
关键词： Fiber modal interferometer,Core-offset,Optical fiber sensor,Refractive index measurement
更新于2025-09-23 15:22:29
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Cascaded tilted fiber Bragg grating for enhanced refractive index sensing
摘要： We proposed and experimentally demonstrated a cascaded tilted fiber Bragg grating (TFBG) for enhanced refractive index sensing. The TFBG is UV-inscribed in series in ordinary single-mode fiber (SMF) and reduced-diameter SMF with the same tilt angle, and then excites two sets of superposed spectral combs of cladding modes. The cascaded TFBG with total length of 18 mm has a much wider wavelength range over 100 nm and narrower wavelength separation than that of a TFBG only in the SMF, enabling an enlarged range and a higher accuracy of refractive index measurement. The fabricated TFBG with the merits of enhanced sensing capability and temperature self-calibration presents great potentials in the biochemical sensing applications.
关键词： refractive index measurement,tilted fiber Bragg grating,fiber optics sensors
更新于2025-09-19 17:15:36
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High-Speed and High-Resolution Microwave Photonic Interrogation of a Fiber-Optic Refractometer With Plasmonic Spectral Comb
摘要： Microwave photonic interrogation of a high-speed and high-resolution refractive index (RI) sensor based on a tilted fiber Bragg grating with surface plasmon resonance (TFBG-SPR) is proposed and experimentally demonstrated. Instead of demodulating the wavelength shift or intensity change of a TFBG-SPR spectrum in the optical domain, we convert the TFBG-SPR spectrum to the time domain based on spectral shaping (SS) and wavelength-to-time (WTT) mapping and use a digital signal processor (DSP) to extract the RI information at a high speed and high resolution. In the experiment, when an Au-coated TFBG is immersed in a solution, the TFBG-SPR spectrum will produce a dip. When the RI changes, the location of the dip in the TFBG-SPR spectrum will shift, which is a function of the RI. By passing a broadband frequency-chirped optical pulse generated by a frequency swept laser source to the TFBG-SPR and detecting the optical pulse at the output of the TFBG-SPR at a photodetector (PD), due to SS-WTT mapping, a temporal waveform with its shape identical to the optical spectrum is produced. A DSP is then used to extract the SPR envelope information from the temporal waveform. By monitoring the changes of the SPR envelope, the RI information is interrogated with a high resolution of 1.123×10-6 RIU at a high speed over 20 kHz.
关键词： Surface plasmon resonance,Tilted fiber Bragg grating,Microwave photonics,Refractive index measurement
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - High-Sensitive All-Fiber Fabry-Perot Interferometer Gas Refractive Index Sensor Based on Lateral offset Splicing and Vernier Effect
摘要： Abstract—A high-sensitivity all-fiber Fabry-Perot interferometer (FPI) gas refractive index (RI) sensor based on lateral offset splicing and Vernier Effect is proposed. The sensing head consist of a reference FPI and a sensing FPI. A reference FPI and the sensing FPI is connected by two circulators. The sensing FPI is an open cavity made by lateral offset splicing of single mode fibers (SMFs), and the reference FPI is spliced by SMF and fiber tube. The Cascaded double-cavity produces a Vernier Effect and improves the sensitivity of gas RI. Experimental results show that the sensor has a high gas RI sensitivity of 16335.96 nm/RIU. The sensor has broad application prospects in gas composition detection, environmental monitoring, biosensors and other fields.
关键词： Fabry-Perot Interferometer,Fiber Optics Sensors,Vernier Effect,Gas Refractive Index Measurement
更新于2025-09-16 10:30:52
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A Green Slab Waveguide for Plasmonic Sensors Based on Bacterial Cellulose
摘要： We use as optical waveguide a green composite, based on bacterial cellulose (BC). More specifically, we have sputtered a thin gold film on this innovative slab waveguide for obtaining a Localized Surface Plasmon Resonance (LSPR) sensor. Experimental results confirm the possibility of using the BC based composite as an environmental friendly optical sensor platform with plasmonic capabilities, which could be exploited for realizing disposable biosensors. The new optical sensor has been used by combining it with optical fibers. The fibers connect the green disposable optical sensor with a light source and with a spectrometer. The device has been tested by measuring the refractive index of different water-glycerin solutions.
关键词： refractive index measurement,sustainable development,localized surface plasmon resonance,bacterial cellulose,optical sensors
更新于2025-09-12 10:27:22
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Measurement of In-fiber Refractive Index Change Using a Mach-Zehnder Interferometer
摘要： We report, for the first time, the use of a fiber optic Mach-Zehnder interferometer to measure core refractive index changes written by an ultrafast laser irradiation. The core-offset interferometer was constructed by splicing a slightly misaligned stub of standard single mode fiber between lead-in and lead-out optical fibers. When the core refractive index of an in-fiber interferometer is altered, it changes the phase of the core light. Since the phase of light propagating in the cladding (reference arm) remains unchanged, the transmission fringe pattern of the interferometer observes a spectral shift. The spectral shift was used to quantify the effective core refractive index change in a standard single mode fiber. Measurement of effective refractive index changes as high as 0.01356 and as low as 0.000475 are reported in this work.
关键词： effective refractive index change,fiber-optic sensor,ultrafast laser,Mach-Zehnder interferometer,in-fiber refractive index measurement
更新于2025-09-04 15:30:14