1
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Zhu C, Alsalman O, Huang J. Fs-Laser Fabricated Miniature Fabry-Perot Interferometer in a No-Core Fiber for High-Temperature Applications. SENSORS (BASEL, SWITZERLAND) 2023; 23:7754. [PMID: 37765811 PMCID: PMC10534877 DOI: 10.3390/s23187754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/29/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023]
Abstract
This paper reports a fiber in-line Fabry-Perot interferometer (FPI) fabricated in a no-core fiber using the direct femtosecond laser writing technique for high-temperature sensing applications. Two in-line reflectors are directly inscribed in a no-core fiber to construct a low-finesse FPI. Fringe visibility greater than 10 dB is obtained from the reflection spectra of the fabricated no-core fiber FPIs. Temperature responses of a prototype no-core fiber FPI are characterized up to 1000 °C. The proposed configuration is compact and easy to fabricate, making it attractive for sensing applications in high-temperature harsh environments.
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Affiliation(s)
- Chen Zhu
- Research Center for Optical Fiber Sensing, Zhejiang Laboratory, Hangzhou 311100, China
| | - Osamah Alsalman
- Department of Electrical Engineering, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia
| | - Jie Huang
- Department of Electrical and Computer Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA
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2
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Jin W, Zhang X, Liu XQ. Highly birefringent one-air-hole panda fiber. OPTICS LETTERS 2023; 48:1004-1007. [PMID: 36790990 DOI: 10.1364/ol.482214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 01/10/2023] [Indexed: 06/18/2023]
Abstract
This Letter proposes a highly birefringent one-air-hole panda fiber, which is fabricated by corroding a single stress zone of the traditional panda-type polarization-maintaining fiber (PMF). An additional geometric asymmetry is induced in the fiber to increase the birefringence effect and enhance the light-matter interaction, which improves the performance of the sensor and the device applications of the special fiber. A theoretical and experimental analysis of the one-air-hole panda fiber demonstrates that the birefringence of the fiber can be of the order of 10-3, which is one order of magnitude higher than that of the traditional panda-type fiber. The corroded region provides a microchannel to be filled with a functional material to compose optical fiber sensors; a sample of a salt solution was filled into the microchannel to measure the refractive index with a sensitivity of 3760 nm/RIU (refractive index units).
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3
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Lu C, Nikbakht H, Yusuf Erdolu M, van Someren B, Akca BI. Tapered tip optical fibers for measuring ultra-small refractive index changes with record high sensitivity. OPTICS LETTERS 2022; 47:6281-6284. [PMID: 37219227 DOI: 10.1364/ol.477288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 11/09/2022] [Indexed: 05/24/2023]
Abstract
Here we demonstrate an inexpensive, simple, and ultra-sensitive refractive index sensor based on a tapered tip optical fiber combined with a straightforward image analysis method. The output profile of this fiber exhibits circular fringe patterns whose intensity distribution dramatically changes even with ultra-small refractive index variations in the surrounding medium. The sensitivity of the fiber sensor is measured using different concentrations of saline solutions with a transmission setup consisting of a single wavelength light source, a cuvette, an objective lens, and a camera. By analyzing the areal changes in the center of the fringe patterns for each saline solution, we obtain an unprecedented sensitivity value of 24,160 dB/RIU (refractive index unit), which is the highest value reported so far among intensity-modulated fiber refractometers. The resolution of the sensor is calculated to be 6.9 ×10-9. Moreover, we measure the sensitivity of the fiber tip in the backreflection mode using salt-water solutions and obtained a sensitivity value of 620 dB/RIU. This sensor is ultra-sensitive, simple, easy to fabricate, and low-cost, which makes it a promising tool for on-site measurements and point-of-care applications.
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Sanchez-Gonzalez A, Perez-Herrera RA, Roldan-Varona P, Duran-Escudero M, Rodriguez-Cobo L, Lopez-Higuera JM, Lopez-Amo M. A Dual-Wavelength Fiber Laser Sensor with Temperature and Strain Discrimination. SENSORS (BASEL, SWITZERLAND) 2022; 22:6888. [PMID: 36146237 PMCID: PMC9504534 DOI: 10.3390/s22186888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/04/2022] [Accepted: 09/11/2022] [Indexed: 06/16/2023]
Abstract
This work presents a dual-wavelength C-band erbium-doped fiber laser assisted by an artificial backscatter reflector. This fiber-based reflector, inscribed by femtosecond laser direct writing, was fabricated into a single mode fiber with a length of 32 mm. The dual-wavelength laser obtained, centered at 1527.7 nm and 1530.81 nm, showed an optical signal-to-noise ratio over 46 dB when pumped at 150 mW. Another feature of this laser was that the power difference between the two channels was just 0.02 dB, regardless of the pump power, resulting in a dual emission laser with high equalization. On the other hand, an output power level and a central wavelength instability as low as 0.3 dB and 0.01 nm were measured, in this order for both channels. Moreover, the threshold pump power was 40 mW. Finally, the performance of this dual-wavelength fiber laser enhanced with a random reflector for sensing applications was studied, achieving the simultaneous measurement of strain and temperature with sensitivities around 1 pm/με and 9.29 pm/°C, respectively.
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Affiliation(s)
- Arturo Sanchez-Gonzalez
- Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain
- Institute of Smart Cities (ISC), Public University of Navarra, 31006 Pamplona, Spain
| | - Rosa Ana Perez-Herrera
- Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain
- Institute of Smart Cities (ISC), Public University of Navarra, 31006 Pamplona, Spain
| | - Pablo Roldan-Varona
- Photonics Engineering Group, University of Cantabria, 39005 Santander, Spain
- CIBER-BBN, Instituto de Salud Carlos III, 28029 Madrid, Spain
- Instituto de Investigacion Sanitaria Valdecilla (IDIVAL), 39005 Cantabria, Spain
| | - Miguel Duran-Escudero
- Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain
| | | | - Jose Miguel Lopez-Higuera
- Photonics Engineering Group, University of Cantabria, 39005 Santander, Spain
- CIBER-BBN, Instituto de Salud Carlos III, 28029 Madrid, Spain
- Instituto de Investigacion Sanitaria Valdecilla (IDIVAL), 39005 Cantabria, Spain
| | - Manuel Lopez-Amo
- Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain
- Institute of Smart Cities (ISC), Public University of Navarra, 31006 Pamplona, Spain
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Hou Y, Jing J, Luo Y, Xu F, Xie W, Ma L, Xia X, Wei Q, Lin Y, Li KH, Chu Z. A Versatile, Incubator-Compatible, Monolithic GaN Photonic Chipscope for Label-Free Monitoring of Live Cell Activities. ADVANCED SCIENCE 2022; 9:e2200910. [PMID: 35404518 PMCID: PMC9189681 DOI: 10.1002/advs.202200910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/16/2022] [Indexed: 02/05/2023]
Abstract
The ability to quantitatively monitor various cellular activities is critical for understanding their biological functions and the therapeutic response of cells to drugs. Unfortunately, existing approaches such as fluorescent staining and impedance-based methods are often hindered by their multiple time-consuming preparation steps, sophisticated labeling procedures, and complicated apparatus. The cost-effective, monolithic gallium nitride (GaN) photonic chip has been demonstrated as an ultrasensitive and ultracompact optical refractometer in a previous work, but it has never been applied to cell studies. Here, for the first time, the so-called GaN chipscope is proposed to quantitatively monitor the progression of different intracellular processes in a label-free manner. Specifically, the GaN-based monolithic chip enables not only a photoelectric readout of cellular/subcellular refractive index changes but also the direct imaging of cellular/subcellular ultrastructural features using a customized differential interference contrast (DIC) microscope. The miniaturized chipscope adopts an ultracompact design, which can be readily mounted with conventional cell culture dishes and placed inside standard cell incubators for real-time observation of cell activities. As a proof-of-concept demonstration, its applications are explored in 1) cell adhesion dynamics monitoring, 2) drug screening, and 3) cell differentiation studies, highlighting its potential in broad fundamental cell biology studies as well as in clinical applications.
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Affiliation(s)
- Yong Hou
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong China
| | - Jixiang Jing
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong China
| | - Yumeng Luo
- School of Microelectronics Southern University of Science and Technology Shenzhen 518055 China
| | - Feng Xu
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong China
| | - Wenyan Xie
- Department of Biotherapy State Key Laboratory of Biotherapy and Cancer Center West China Hospital Sichuan University Chengdu Sichuan 610065 China
| | - Linjie Ma
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong China
| | - Xingyu Xia
- Department of Mechanical Engineering The University of Hong Kong Hong Kong China
| | - Qiang Wei
- College of Polymer Science and Engineering State Key Laboratory of Polymer Materials and Engineering Sichuan University Chengdu 610065 China
| | - Yuan Lin
- Department of Mechanical Engineering The University of Hong Kong Hong Kong China
- Advanced Biomedical Instrumentation Centre Hong Kong Science Park Shatin New Territories Hong Kong
| | - Kwai Hei Li
- School of Microelectronics Southern University of Science and Technology Shenzhen 518055 China
| | - Zhiqin Chu
- Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong China
- School of Biomedical Sciences The University of Hong Kong Hong Kong China
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6
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Zhu C, Huang J. Microwave-photonic optical fiber interferometers for refractive index sensing with high sensitivity and a tunable dynamic range. OPTICS LETTERS 2021; 46:2180-2183. [PMID: 33929449 DOI: 10.1364/ol.420618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
We propose and demonstrate an extremely simple yet novel sensing strategy for measurements of a refractive index (RI) based on microwave-photonic optical fiber interferometry. A hybrid interferometric system based on an incoherent optical interferometer (i.e., a Michelson interferometer [MI]) and a coherent optical interferometer (i.e., a Fabry-Perot interferometer [FPI]) is constructed simply by using a low-cost off-the-shelf fiber coupler. The sensing arm of the MI is highly sensitive to a surrounding RI based on Fresnel reflection, where variations of the ambient RI cause changes in both the reflection magnitudes of the resonance frequencies and fringe visibility of the reflection spectra in the microwave domain. The coherent FPI is employed to tune the dynamic range of the MI by adjusting the effective reflectance of the reference arm of the MI. Essentially, other approaches that can vary the reflectance of the reference arm of the MI can also be used to tune the dynamic range of the system based on the proposed strategy. The experimental results are in good agreement with theoretical predictions. The prominent advantages of the sensor, including low cost, ease of fabrication, robustness, compactness, high sensitivity, and tunable dynamic range, make it a strong candidate in various chemical, biological, and environmental applications.
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Chen L, An X, Jing J, Jin H, Chu Z, Li KH. Ultracompact Chip-Scale Refractometer Based on an InGaN-Based Monolithic Photonic Chip. ACS APPLIED MATERIALS & INTERFACES 2020; 12:49748-49754. [PMID: 33094997 DOI: 10.1021/acsami.0c13144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Optical refractometer constitutes the core element for many applications, from determining the purity and concentration of pharmaceutical ingredients to measuring the sugar content in food and beverages, and the analysis of petroleum. Here, we demonstrated the monolithic integration of light-emitting diodes (LEDs) and photodetectors (PDs) to fabricate ultracompact refractometers with a chip size of 475 × 320 μm2. The light emission and photodetection properties of the devices containing the same InGaN/GaN multi-quantum wells have been characterized, confirming that the PD can respond to the emission of the LED. The flip-chip assembly of the chip enables the exposed sapphire substrate to be in direct contact with the solution, and the refractive index sensing capability governed by the change of critical angle and Fresnel reflection at the sapphire/solution interface has been investigated. The processing of the optically smooth surface of sapphire and the integration of high-reflectance distributed Bragg reflector beneath the devices facilitate the amount of light received by the PD. The monolithic chip is capable of detecting solutions with a refractive index ranging from 1.3325 to 1.5148 RIU and exhibits a sensitivity of 7.77 μA/RIU and a resolution of 6.4 × 10-6 RIU at the LED current of 10 mA. Rapid real-time responses of 33.9 ms for rise time and 34.7 ms for fall time are obtained in the detected photocurrent, thereby verifying the feasibility of the chip-scale refractometer.
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Affiliation(s)
- Liang Chen
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xiaoshuai An
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jixiang Jing
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Electrical and Electronic Engineering (Joint Appointment with School of Biomedical Sciences), The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Haotian Jin
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhiqin Chu
- Department of Electrical and Electronic Engineering (Joint Appointment with School of Biomedical Sciences), The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Kwai Hei Li
- School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China
- Engineering Research Center of Integrated Circuits for Next-Generation Communications, Ministry of Education, Southern University of Science and Technology, Shenzhen 518055, China
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8
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Barrios CA. Pressure Sensitive Adhesive Tape: A Versatile Material Platform for Optical Sensors. SENSORS (BASEL, SWITZERLAND) 2020; 20:s20185303. [PMID: 32948000 PMCID: PMC7570651 DOI: 10.3390/s20185303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/08/2020] [Accepted: 09/13/2020] [Indexed: 06/11/2023]
Abstract
Pressure sensitive adhesive (PSA) tapes are a versatile, safe and easy-to-use solution for fastening, sealing, masking, or joining. They are widely employed in daily life, from domestic use to industrial applications in sectors such as construction and the automotive industry. In recent years, PSA tapes have found a place in the field of micro- and nanotechnology, particularly in contact transfer techniques where they can be used as either sacrificial layers or flexible substrates. As a consequence, various optical sensing configurations based on PSA tapes have been developed. In this paper, recent achievements related to the use of PSA tapes as functional and integral parts of optical sensors are reviewed. These include refractive index sensors, optomechanical sensors and vapor sensors.
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Affiliation(s)
- Carlos Angulo Barrios
- Institute for Optoelectronic Systems and Microtechnology (ISOM), ETSI Telecomunicación, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain;
- Department of Photonics and Bioengineering (TFB), ETSI Telecomunicación, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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9
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Ji P, Jiang S, Lee SS. Fiber Reshaping-Based Refractive Index Sensor Interrogated through Both Intensity and Wavelength Detection. SENSORS 2019; 19:s19112477. [PMID: 31151242 PMCID: PMC6603556 DOI: 10.3390/s19112477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 11/21/2022]
Abstract
A fiber reshaping-based refractive index (RI) sensor is proposed relying on both optical intensity variation and wavelength shift. The objective of this study is to completely reshape the core and to ultimately mimic a coreless fiber, thereby creating a highly efficient multimode interference (MMI) coupler. Thus, propagation modes are permitted to leak out into the cladding and eventually escape out of the fiber, depending on the surrounding environment. Two interrogation mechanisms based on both the intensity variation and wavelength shift are employed to investigate the performance of the RI sensor, with the assistance of leaky-mode and MMI theories. By monitoring the output intensity difference and the wavelength shift, the proposed RI sensor exhibits high average sensitivities of 185 dB/RIU and 3912 nm/RIU in a broad range from 1.339 to 1.443, respectively. The operating range and sensitivity can be adjusted by controlling the interaction length, which is appealing for a wide range of applications in industry and bioscience research.
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Affiliation(s)
- Peng Ji
- Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 01897, Korea.
| | - Shiru Jiang
- Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 01897, Korea.
| | - Sang-Shin Lee
- Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 01897, Korea.
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Pevec S, Donlagic D. Miniature fiber-optic Fabry-Perot refractive index sensor for gas sensing with a resolution of 5x10 -9 RIU. OPTICS EXPRESS 2018; 26:23868-23882. [PMID: 30184882 DOI: 10.1364/oe.26.023868] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/22/2018] [Indexed: 06/08/2023]
Abstract
This paper presents a micro-machined, high-resolution refractive index sensor suitable for monitoring of small changes in the composition of gases. Experimentally demonstrated measurement resolution, induced by gas composition variation, proved to be in the range of 5x10-9 of a Refractive Index Unit (RIU). The proposed all-silica, all-fiber sensor consists of an open-path Fabry-Perot micro-cavity that includes an in-fiber collimation and temperature-sensing segment. It is shown that a sensor's resolution depends strongly on the signal interrogator's properties and that, for a given interrogator, there is an optimum Fabry-Perot cavity length that yields the highest system resolution. Furthermore, high-resolution pressure and in situ temperature compositions of measurement results are required to obtain an unambiguous correlation between the gas composition and measured Refractive Index within the presented resolution range.
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Gray AC, Jantzen A, Gow PC, Smith DH, Gawith CBE, Smith PGR, Holmes C. Leaky mode integrated optical fibre refractometer. OPTICS EXPRESS 2018; 26:9155-9164. [PMID: 29715871 DOI: 10.1364/oe.26.009155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/02/2018] [Indexed: 06/08/2023]
Abstract
A route to monitor external refractive indices greater than the core index of the waveguide is presented. Initial application utilizes an integrated optical fibre (IOF) platform due to its potential for use in harsh environment sensing. IOF is fabricated using a bespoke flame hydrolysis deposition process to fuse an optical fibre to a planar substrate achieving an optical quality, ruggedized glass layer between the fibre and substrate was fabricated. The presented refractometer is created by direct UV writing of multiple fibre Bragg gratings into an etched (22 μm diameter) optical fibre post fabrication. Linear regression analysis is applied to quantify propagation loss by monitoring each FBG's back reflected power. The device operates with a sensitivity of approximately 350 dB/cm/RIU at a refractive index of 1.451 at 1550 nm. Numerical simulations using a transfer matrix method are presented and potential routes for development are discussed.
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Chen Z, Xiong S, Gao S, Zhang H, Wan L, Huang X, Huang B, Feng Y, Liu W, Li Z. High-Temperature Sensor Based on Fabry-Perot Interferometer in Microfiber Tip. SENSORS 2018; 18:s18010202. [PMID: 29329221 PMCID: PMC5795513 DOI: 10.3390/s18010202] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/06/2018] [Accepted: 01/08/2018] [Indexed: 11/16/2022]
Abstract
A miniaturized tip Fabry-Perot interferometer (tip-FPI) is proposed for high-temperature sensing. It is simply fabricated for the first time by splicing a short length of microfiber (MF) to the cleaved end of a standard single mode fiber (SMF) with precise control of the relative cross section position. Such a MF acts as a Fabry-Perot (FP) cavity and serves as a tip sensor. A change in temperature modifies the length and refractive index of the FP cavity, and then a corresponding change in the reflected interference spectrum can be observed. High temperatures of up to 1000 °C are measured in the experiments, and a high sensitivity of 13.6 pm/°C is achieved. This compact sensor, with tip diameter and length both of tens of microns, is suitable for localized detection, especially in harsh environments.
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Affiliation(s)
- Zhenshi Chen
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou 510632, China.
| | - Songsong Xiong
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Shecheng Gao
- Department of Electronic Engineering, College of Information Science and Techonology, Jinan University, Guangzhou 510632, China.
| | - Hui Zhang
- School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China.
| | - Lei Wan
- Institute of Optoelectronic Material and Technology, South China Normal University, Guangzhou 510631, China.
| | - Xincheng Huang
- Department of Electronic Engineering, College of Information Science and Techonology, Jinan University, Guangzhou 510632, China.
| | - Bingsen Huang
- Department of Electronic Engineering, College of Information Science and Techonology, Jinan University, Guangzhou 510632, China.
| | - Yuanhua Feng
- Department of Electronic Engineering, College of Information Science and Techonology, Jinan University, Guangzhou 510632, China.
| | - Weiping Liu
- Department of Electronic Engineering, College of Information Science and Techonology, Jinan University, Guangzhou 510632, China.
| | - Zhaohui Li
- State Key Laboratory of Optoelectronic Materials and Technologies and School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
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Chen P, Shu X, Cao H, Sugden K. High-sensitivity and large-dynamic-range refractive index sensors employing weak composite Fabry-Perot cavities. OPTICS LETTERS 2017; 42:3145-3148. [PMID: 28809894 DOI: 10.1364/ol.42.003145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/17/2017] [Indexed: 06/07/2023]
Abstract
Most sensors face a common trade-off between high sensitivity and a large dynamic range. We demonstrate here an all-fiber refractometer based on a dual-cavity Fabry-Perot interferometer (FPI) that possesses the advantage of both high sensitivity and a large dynamic range. Since the two composite cavities have a large cavity length difference, one can observe both fine and coarse fringes, which correspond to the long cavity and the short cavity, respectively. The short-cavity FPI and the use of an intensity demodulation method mean that the individual fine fringe dips correspond to a series of quasi-continuous highly sensitive zones for refractive index measurement. By calculating the parameters of the composite FPI, we find that the range of the ultra-sensitive zones can be considerably adjusted to suit the end requirements. The experimental trends are in good agreement with the theoretical predictions. The co-existence of high sensitivity and a large dynamic range in a composite FPI is of great significance to practical RI measurements.
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