Microstructured Optical Fiber Sensor Research Articles

Novel Microstructured Optical Fiber Sensor Based on Multi-Beam Interference

Recent progress in designing optimized microstructured optical fiber spreads an application scenario of optical fiber sensing. In this letter, we demonstrate a novel three-core microstructured optical fiber (TMOF) spliced with single mode fibers (SMFs). Due to low crosstalk and different effective refractive index between three cores in TMOF, multi-beam interference is achieved and verified based on both of experiments and theoretical analysis. In addition, the bending response could also be recorded by the transmission spectrum of TMOF because of the asymmetry of three core effective refractive index. Owing to the consistency of cores responding to temperature changes, the TMOF can effectively suppress the influence of temperature. Theses excellent sensing characteristics indicate the TMOF splicing with SMFs is promising in the field of bending, integrated Mach Zehnder devices and multi-parameter sensing measurement under different temperature.

Micro-structured optical fiber sensor for simultaneous measurement of temperature and refractive index

Abstract Through using micro-machining method for optical fiber sensor, a kind of miniature, compact and composite structural all-fiber sensor is presented. Based on manufacturing two micro-holes with certain distance in ordinary single-mode fiber Bragg grating (FBG) by excimer laser processing technique, we fabricate a dual Fabry–Perot-FBG (FP-FBG) composite fiber interferometric sensor, which can be used in simultaneous measurement for liquid’s refractive index (RI) and temperature change. Due to every micro-hole and the dual micro-holes in fiber acting as different Fabry–Perot (FP) cavities, this kind of sensor has not only different RI sensitivities but also different temperature sensitivities, which are corresponding to the wavelength shifts of the fine interference fringes and spectral envelope, respectively. The experimental results show that the spectral wavelength shift keep better linear response for temperature and RI change, so that we can select the higher temperature and RI sensitivities as well as the analyzed sensitivities of FBG to utilize them for constituting a sensitivity coefficients matrix. Finally, the variations of liquid’s temperature and RI are detected effectively, and the resolutions can reach to 0.1 °C and 1.0 × 10 - 5 RIU. These characteristics are what other single-type sensors don’t have, so that this kind of all-fiber dual FP-FBG composite fiber interferometric sensor can be used in extremely tiny liquid environment for measuring different physical quantities simultaneously.

Microstructured Optical Fiber Sensors

In this paper, a review of microstructured optical fiber (MOF) sensors is given. Various kinds of MOFs are described and their sensing applications are summarized. Two main types of MOF sensors in terms of grating based and interferometry based are reviewed. In particular, several types of microstructured optical fibers designed for sensing applications in our works are demonstrated, including the measurement of physical parameters, e.g., pressure, strain, torsion, temperature, and the detection of biomedical parameters such as refractive index and microfluidic flow rate. The basic design principles of MOF sensors based on fiber Bragg grating and interferometers are given. Comparisons of the performances of the fibers and sensors are also conducted according to the relevant topics.

Suspended-core microstructured fiber for refractometric detection of liquids.

A silica suspended-core microstructured optical fiber sensor for detection of liquids, operating at 1550nm, is analyzed. The sensing principle is based on the evanescent wave overlap into a tested analyte, which is filled via capillary forces into the cladding holes. Validations for analytes in the refractive index range of 1.35-1.43 are carried out with liquid-analyte-filling-length limits being studied both theoretically and experimentally. We prove, for the first time to our knowledge, that an extreme sensitivity of 342.86dB/RIU and resolution of 4.4×10-5 can be achieved. This sensor represents a high-quality alternative for applications requiring a facile, low-cost solution.

A Surface Plasmon Biosensor Based on a D-Shaped Microstructured Optical Fiber With Rectangular Lattice

A numerical investigation of a surface plasmon biosensor based on D-shaped microstructured optical fiber (MOF) with rectangular lattice is presented. A full-vector finite-element method is applied to analyze the resonance coupling properties. By adjusting the diameters of two large air holes, the proposed biosensor shows excellent performance. High sensitivity and narrow full-width at half-maximum (FWHM) can be achieved. In particular, the figure of merit can reach to 478.3RIU-1, which is to our knowledge the highest among the reported MOF sensors. In the last part, the influence of coating thickness on the sensing performance has been considered.

Selectively Liquid-Infiltrated Microstructured Optical Fiber for Simultaneous Temperature and Force Measurement

A dual-parameter sensor based on a liquid-infiltrated microstructured optical fiber (MOF) is constructed by selective liquid infiltration of one particular cladding air hole in the MOF. The fundamental core mode could be simultaneously coupled to several higher order modes of the adjacent liquid rod waveguide when the phase-matching condition is satisfied, resulting in the emergence of multiple resonance peaks with different sensing characteristics. Our proposed liquid-infiltrated MOF sensor has several advantages, such as high sensitivity and a large measurement range. Moreover, it is able to resolve the temperature-force cross-sensitivity issue that is commonly encountered in most practically deployed sensing components.

Analyte-filled core self-calibration microstructured optical fiber based plasmonic sensor for detecting high refractive index aqueous analyte

This paper presents a theoretical investigation on an analyte-filled core self-calibration microstructured optical fiber plasmonic refractive index sensor. The proposed microstructured optical fiber sensor introduces the concept of simultaneous detection in different ranges of wavelength because the sensing performance of the sensor in different wavelength ranges is relatively high, which will be useful for high accuracy measurement. The resonant peak 1 and peak 2 are stronger and more sensitive to the variation of analyte refractive index than any other peaks in this kind of microstructured optical fiber. An average refractive index sensitivity of −4354.3nm/RIU (refractive index unit) and 2280nm/RIU in the dynamic index range from 1.46 to 1.485 as well as −2660nm/RIU and −4240nm/RIU from 1.50 to 1.52 corresponding to the peak 1 and peak 2 can be obtained, respectively. The self-calibration sensor demonstrates high linearity and accuracy. The influence of the structural parameters on the plasmonic excitations is also studied, with a view of turning and optimizing the resonant spectrum.

Shear stress sensing with Bragg grating-based sensors in microstructured optical fibers

We demonstrate shear stress sensing with a Bragg grating-based microstructured optical fiber sensor embedded in a single lap adhesive joint. We achieved an unprecedented shear stress sensitivity of 59.8 pm/MPa when the joint is loaded in tension. This corresponds to a shear strain sensitivity of 0.01 pm/µε. We verified these results with 2D and 3D finite element modeling. A comparative FEM study with conventional highly birefringent side-hole and bow-tie fibers shows that our dedicated fiber design yields a fourfold sensitivity improvement.

基于银纳米线的类熊猫型微结构光纤传感器

基于银纳米线的类熊猫型微结构光纤传感器

Microfluidic refractive-index sensors based on small-hole microstructured optical fiber Bragg gratings

A microstructured optical fiber (MOF) Bragg grating is presented for microfluidic sensing applications. The MOF is specially designed to be with a large amount of microholes for developing ultrasensitive sensors based on inner coating and surface effects. With the fabrication of fiber Bragg grating (FBG), such an MOF sensor has been demonstrated for monitoring the fluid flowing through microholes. Experimental results reveal that the sensitivity of the sensor depends on both the refractive-index range of measurement and the order of fiber modes. The temperature dependency of the sensor has also been measured and compared with that of conventional FBGs.

Towards biochips using microstructured optical fiber sensors

In this paper we present the first incorporation of a microstructured optical fiber (MOF) into biochip applications. A 16-mm-long piece of MOF is incorporated into an optic-fluidic coupler chip, which is fabricated in PMMA polymer using a CO(2) laser. The developed chip configuration allows the continuous control of liquid flow through the MOF and simultaneous optical characterization. While integrated in the chip, the MOF is functionalized towards the capture of a specific single-stranded DNA string by immobilizing a sensing layer on the microstructured internal surfaces of the fiber. The sensing layer contains the DNA string complementary to the target DNA sequence and thus operates through the highly selective DNA hybridization process. Optical detection of the captured DNA was carried out using the evanescent-wave-sensing principle. Owing to the small size of the chip, the presented technique allows for analysis of sample volumes down to 300 nL and the fabrication of miniaturized portable devices.