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Photonic Sensors
Journal Prestige (SJR): 0.432

Citation Impact (citeScore): 2
Number of Followers: 8

This is an Open Access Journal

Open Access journal
ISSN (Print) 1674-9251 - ISSN (Online) 2190-7439
Published by SpringerOpen

[229 journals]

Micromachined Infrared Thermopile Detector Based on a Suspended Film
Structure
- Abstract: Abstract The micro-electromechanical system (MEMS) infrared thermopile is the core working device of modern information detection systems such as spectrometers, gas sensors, and remote temperature sensors. We presented two different structures of MEMS infrared thermopiles based on suspended film structures. They both deposited silicon nitride over the entire surface as a passivated absorber layer in place of a separate absorber zone, and the thermocouple strip was oriented in the same direction as the temperature gradient. The same MEMS preparation process was used and finally two different structures of the thermopile were characterized separately for testing to verify the impact of our design on the detector. The test results show that the circular and double-ended symmetrical thermopile detectors have responsivities of 27.932 V/W and 23.205 V/W, specific detectivities of 12.1×107 cm·Hz1/2·W−1 and 10.1×107 cm·Hz1/2·W−1, and response time of 26.2 ms and 27.06 ms, respectively. In addition, rectangular double-ended symmetric thermopile has a larger field of view than a circular thermopile detector, but is not as mechanically stable as a circular thermopile.
  PubDate: 2023-03-21
Feasibility of Integrating Bimetallic Au-Ag Non-Alloys Nanoparticles
Embedded in Reduced Graphene Oxide Photodetector
- Abstract: Abstract To coordinate the resonant wavelength of the plasmonic nanoparticles (NPs), the emission band of the reduced graphene oxide (rGO) photodetector at the NIR-region is crucial for the optimal plasmon-enhanced luminescence in the device. In contrast to monometallic NPs, where limits the dimensions and extended resonant wavelength, we integrated an Au-Ag bimetallic NPs (BMNPs) to enable resonance tuning at the longer wavelength at the excitation source of 785 nm. These features showed an increase in radiative recombination rates as well as the quantum yield efficiency of the device. The BMNPs were produced from the dewetting process of 600 °C and 500 °C, both at 1 min after the deposition thickness layer of Au (8 nm) and Ag (10 nm) on the Si substrate using the electron-beam evaporation process. Our BMNPs-rGO photodetector exhibited the responsivity of 2.25 · A W−1, Jones of specific detectivity of 2.45×1011Jones, and external quantum efficiency (EQE) of 356%. The rise time and fall time for the photodetector were 32 ns and 186 ns, respectively. This work provided an essential information to enable the versatile plasmon-enhanced application in 2-dimensional (2D) material optoelectronic devices.
  PubDate: 2023-03-06
Accounting for Polychromatic Light in Virtual Shack-Hartmann Wavefront
Sensing
- Abstract: Abstract Virtual Shack-Hartmann wavefront sensing (vSHWS) has some significant advantages and is promising for aberration measurement in the field of biomedical optical imaging. The illumination sources used in vSHWS are almost broadband, but are treated as monochromatic sources (only using center wavelength) in current data processing, which may cause errors. This work proposed a data processing method to take into account the multiple wavelengths of the broadband spectrum, named multiple-wavelength centroid-weighting method. Its feasibility was demonstrated through a series of simulations. A wavefront generated with a set of statistical human ocular aberrations was used as the target wavefront to evaluate the performance of the proposed and current methods. The results showed that their performance was very close when used for the symmetrical, but the wavefront error of the proposed method was much smaller than that of the current method when used for the asymmetrical spectrum, especially for the broader spectrum. These results were also validated by using 20 sets of clinical human ocular aberrations including normal and diseased eyes. The proposed method and the obtained conclusions have important implications for the application of vSHWS.
  PubDate: 2023-03-01
Sensitivity-Enhanced Hot-Wire Anemometer by Using Cladding-Etched Fiber
Bragg Grating
- Abstract: Abstract A sensitivity-enhanced hot-wire anemometer based on a cladding-etched optical fiber Bragg grating (FBG) coated with a layer of silver film and optically heated by using a 1480 nm laser diode is demonstrated. The silver film absorbs the laser power to heat the FBG to a certain high temperature and the airflow cools down the FBG hot-wire with the cooling effect and hence the Bragg wavelength of the FBG is determined by the airflow velocity. Experimental measurement results show that the heating efficiency of the FBG hot wire is improved by 3.8 times in magnitude by etching the fiber cladding from 125 µm down to 73.4 µm, and the achieved airflow velocity sensitivities, under a laser power of 200 mW, are −3 180 pm/(m/s), −889 pm/(m/s), −268 pm/(m/s), and −8.7 pm/(m/s) at different airflow velocities of 0.1 m/s, 0.5 m/s, 1.5 m/s, and 17 m/s, respectively. In comparison, the sensitivities are only −2193 pm/(m/s), −567 pm/(m/s), −161 pm/(m/s), and −4.9 pm/(m/s) for the reference anemometer without cladding etching even at a much higher heating laser power of 530 mW. These results prove that the method by using a cladding-etched FBG to improve sensitivity of FBG-based hot-wire anemometers works and the sensitivity is improved significantly.
  PubDate: 2023-02-22
High Sensitivity Temperature Sensor Based on Harmonic Vernier Effect
- Abstract: Abstract A high-sensitivity temperature sensor based on the harmonic Vernier effect is proposed and verified by experiments. The main component of the sensor is a Sagnac interferometer consisting of two sections of polarization maintaining fibers (PMFs) spliced with an intersection angle of 45° between their fast axes. The harmonic Vernier effect is achieved by setting the length of one of the PMFs an integral multiple (i-times) of the length of the other plus a detuning factor. Compared with the Sagnac interferometer based on the fundamental Vernier effect, the temperature sensitivity of the harmonic Vernier effect is higher, reaching i+1 times of that of the fundamental Vernier effect (i is the order of the harmonic).
  PubDate: 2023-02-10
Bias-Independent Inter-Modulation Method for Simultaneously Measuring
Low-Frequency Modulation and Bias Half-Wave Voltages of Mach-Zehnder
Modulators
- Abstract: Abstract A bias-independent inter-modulation method is proposed and demonstrated for measuring low-frequency modulation and bias half-wave voltages of Mach-Zehnder modulators (MZMs). The method consists of simultaneous sinusoidal modulation on the modulation and bias ports of the MZM under test. Sinusoidal-modulated sidebands heterodyne with each other and generate the desired inter-modulation products after photodetection, which allows extracting both the modulation depth and half-wave voltage for the modulation and bias ports of the MZM. Our method is independent of bias voltages of the MZM, which can be canceled out by carefully choosing the sinusoidal-modulation frequencies. Moreover, the proposed method enables the low swing voltage for measuring both the modulation depth and half-wave voltage of MZMs. Experiments indicate that the proposed method features the simple setup and high accuracy for low-frequency response measurement ranging from 1 Hz to 1 MHz.
  PubDate: 2023-01-16
High-Sensitivity Early Detection Biomedical Sensor for Tuberculosis With
Low Losses in the Terahertz Regime Based on Photonic Crystal Fiber
Technology
- Abstract: Abstract Tuberculosis is one of the most contagious and lethal illnesses in the world, according to the World Health Organization. Tuberculosis had the leading mortality rate as a result of a single infection, ranking above HIV/AIDS. Early detection is an essential factor in patient treatment and can improve the survival rate. Detection methods should have high mobility, high accuracy, fast detection, and low losses. This work presents a novel biomedical photonic crystal fiber sensor, which can accurately detect and distinguish between the different types of tuberculosis bacteria. The designed sensor detects these types with high relative sensitivity and negligible losses compared to other photonic crystal fiber-based biomedical sensors. The proposed sensor exhibits a relative sensitivity of 90.6%, an effective area of 4.342×10−8m2, with a negligible confinement loss of 3.13×10−9cm−1, a remarkably low effective material loss of 0.0132cm−1, and a numerical aperture of 0.3462. The proposed sensor is capable of operating in the terahertz regimes over a wide range (1 THz–2.4THz). An abbreviated review of non-optical detection techniques is also presented. An in-depth comparison between this work and recent related photonic crystal fiber-based literature is drawn to validate the efficacy and authenticity of the proposed design.
  PubDate: 2023-01-05
Surface Plasmon Resonance Based Sensor for Amaranth Detection With
Molecularly Imprinted Nanoparticles
- Abstract: Abstract Amaranth imprinted nanoparticles were prepared by two-phase mini emulsion polymerization of hydroxyethyl methacrylate and ethylene glycol dimethacrylate using acrylamide and methacrylic acid as functional monomers. The amaranth non-imprinted nanoparticle was prepared with the same procedure without using amaranth. Amaranth imprinted and non-imprinted nanoparticles were attached on the chip surface modified with allyl mercaptan. The surfaces of the surface plasmon resonance (SPR) sensor were characterized by the ellipsometry, contact angle, and atomic force microscopy. Amaranth solutions with different concentrations (0.1mg/mL–150mg/mL) were prepared with the pH 7.4 phosphate buffer. The limit of detection and limit of quantification were 0.0180mg/mL and 0.06mg/mL, respectively. When the selectivity of the amaranth imprinted SPR sensor was compared with the competing molecules tartrazine and allura red, it was observed that the target molecule amaranth was 5.64 times and 5.18 times more selective than allura red and tartrazine, respectively. The liquid chromatography-mass spectrometry technique (LC-MS) was used for validation studies. According to the results obtained from both SPR sensor and LC-MS analyses, the amaranth recovery (%) from fruit juices was observed between 96% and 99%.
  PubDate: 2023-01-05
High-Performance Quality Factor Based Sensor With Diagonal Cylinder
Metasurface of the Bound State in the Continuum
- Abstract: Abstract High-quality-factor (high-Q-factor) electromagnetic resonance plays an important role in sensor applications. Previously proposed gas refractive index sensors are often limited by the large cavity length or microscale fabrication process in practical applications. Recently, ultra-high Q factor resonance based on the bound state in the continuum (BIC) has provided a feasible approach to solve these problems. In this paper, we propose a metasurface structure consisting of a single size tetramer cylinder. It supports dual band toroidal dipole (TD) resonances driven by BIC. The physical mechanism of double TD resonances is clarified by the multipole decomposition of the metasurface band structure and far-field scattering power. The sensor structure based on this achieves a sensitivity of 518.3 MHz/RIU, and the maximum line width does not exceed 680 kHz. The high-Q-factor electromagnetic resonance has the advantages of polarization independence and simplicity to manufacture. These findings will open up an avenue to develop the ultrasensitive sensor in the gigahertz regime.
  PubDate: 2022-11-17
Coupling of Epsilon-Near-Zero Mode to Mushroom-Type Metamaterial for
Optimizing Infrared Suppression and Radiative Cooling
- Abstract: Abstract We report a complementary metal oxide semiconductor (CMOS) compatible metamaterial-based spectrally selective absorber/emitter (MBSSAE) for infrared (IR) stealth, which has the low absorption/emissivity in the IR atmospheric transmission window (3 µm–5 µm, 8 µm–14 µm) and ultra-high and broadband absorption/emissivity in the IR non-atmospheric window (5 µm–8 µm). We propose a novel method for the broadband absorption/emissivity in 5 µm–8 µm with incorporation of an epsilon-near-zero (ENZ) material between the top patterned aluminum (Al) disks layer and the silicon oxide (SiO2) spacer layer. With an appropriate design, the peaks in the IR atmospheric transmission window can be suppressed while the peak intensity in the non-atmospheric window remains high. The optimized MBSSAE has an average absorption/emissivity less than 10% in 8 µm–14 µm and less than 6% in 3 µm–5 µm. And the average absorption/emissivity in 5 µm–8 µm is approximately over 64%. This proposed scheme may introduce the opportunities for the large-area and low-cost infrared stealth coating, as well as for the radiative cooling, spectral selective thermal detector, optical sensor, and thermophotovoltaic applications.
  PubDate: 2022-11-08
A Depth Sensor Based on Transient Property of Liquid Crystal Lens
- Abstract: Abstract The property of maintaining the lens state of the liquid crystal (LC) lens during the switching between positive and negative lens states is made use of in the fast acquirement of multi-focus images without magnification change. A depth from focus (DFF) pipeline that can generate a low-error depth map and an all-in-focus image is proposed. The depth of the scene is then obtained via DFF pipeline from the captured images. The depth sensor proposed in this paper has the advantages of simple structure, low cost, and long service life.
  PubDate: 2022-11-04
Fiber Fabry-Perot Demodulation System Based on Dual Fizeau Interferometers
- Abstract: Abstract In this study, we present a dual-Fizeau-interferometer-based high-speed and wide-range fiber-optic Fabry-Perot (F-P) demodulation system. We employ two Fizeau interferometers with air cavity thickness satisfying the quadrature requirement to increase the demodulation speed and broaden the demodulation range in order to address the issues of the existing fiber F-P demodulation system’s sluggish demodulation rate and limited range. In order to investigate the demodulation properties of the dual-Fizeau-interferometer-based demodulation system, we derive and create a theoretical model of the system. The theoretical model, which primarily consists of the structural design of the interferometer and the study of the center wavelength of the light sources and their bandwidth selection, is used to construct the optical structure of the demodulation system. According to the calculation results, the demodulated signal exhibits the best contrast ratio when the two light sources’ respective center wavelengths are 780 nm and 850 nm, and their bandwidths are 28 nm and 30 nm. Finally, we finish evaluating the demodulation system’s demodulation performance, parameter calibration, and assembly debugging. The test results demonstrate the constant operation of the demodulation system, an update rate of 100 kHz, a demodulation range of 4.74 µm, and a cavity length resolution of approximately 5 nm. Additionally, the system can perform high speed demodulation thanks to the light emitting diode’s (LED’s) nanosecond level switching speed and the usage of a single point detector.
  PubDate: 2022-10-11
Design and Investigation of a High-Sensitivity Tilt Sensor Based on FBG
- Abstract: Abstract In this paper, a high-sensitivity fiber Bragg grating (FBG) tilt sensor using a cantilever-based structure is introduced. Two FBGs are fixed on a specially designed elastomer. One end of the elastomer is connected to the mass block, and the other end is connected to the shell. The principle of the tilt sensor is introduced in detail, and the mathematical model is established. The performance of the sensor is studied. The results show that there is a good linear relationship between the central wavelength difference of the two FBGs and the tilt angle in the range of −5° to 5°. The repeatability of the sensor is good, and the tilt sensitivity can reach 231.7pm/°. The influence of the silicone oil on the damping capacity of the sensor is studied. The results show that the damping capacity of the sensor has been improved by sealing the silicone oil inside the shell of the sensor. The field test is carried out on a pier of an elevated bridge, and the result is good, which verifies the practicability of the sensor.
  PubDate: 2022-10-02
Investigation of Strain-Temperature Cross-Sensitivity of FBG Strain
Sensors Embedded Onto Different Substrates
- Abstract: Abstract The strain-temperature cross-sensitivity problem easily occurs in the engineering strain monitoring of the self-sensing embedded with fiber Bragg grating (FBG) sensors. In this work, a theoretical investigation of the strain-temperature cross-sensitivity has been performed using the temperature reference grating method. To experimentally observe and theoretically verify the problem, the substrate materials, the preloading technique, and the FBG initial central wavelength were taken as main parameters. And a series of sensitivity coefficients calibration tests and temperature compensation tests have been designed and carried out. It was found that when the FBG sensors were embedded on different substrates, their coefficients of the temperature sensitivity were significantly changed. Besides, the larger the coefficients of thermal expansion (CTE) of substrates were, the higher the temperature sensitivity coefficients would be. On the other hand, the effect of the preloading technique and FBG initial wavelength was negligible on both the strain monitoring and temperature compensation. In the case of similar substrates, we did not observe any difference between temperature sensitivity coefficients of the temperature compensation FBG with one free end or two free ends. The curves of the force along with temperature were almost overlapped with minor differences (less than 1%) gained by FBG sensors and pressure sensors, which verified the accuracy of the temperature compensation method. We suggest that this work can provide efficient solutions to the strain-temperature cross-sensitivity for engineering strain monitoring with the self-sensing element embedded with FBG sensors.
  PubDate: 2022-09-27
A New Ratio-Metric pH Probe, “ThiAKS Green” for Live-Cell pH
Measurements
- Abstract: Abstract Deviation of the H+ concentration from optimum values within the organelles is closely associated with irregular cellular functions that cause the onset of various diseases. Therefore, determining subcellular pH values in live cells and tissues is valuable for diagnostic purposes. In this study, we report a novel ratiometric fluorescence probe 1H-pyrazole-3-carboxylic acid, 4-(benzo[d]thiazol-2-yl)-3-(2,4-dihydroxy-3-methylphenyl)-1H-pyrazole-5-carboxylicacid4-(2-benz othiazolyl)-5-(2,4-dihydroxy-3-methylphenyl), to which we will refer as ThiAKS Green (Thiazole AKyol shifting green), that is pH sensitive. The results presented here show that the probe can penetrate the cell membrane in less than 30 minutes and does not show any detectable toxicity. The measured color shifts up on pH change are linear and most significant around physiological pH (pKa=7.45), thus making this probe suitable for live-cell imaging and intracellular pH measurements. During the long-incubation periods following the application of the probe and the fluorescent microscopy measurements, it shows stable properties and is easy to detect in live cells. In conclusion, the results suggest that ThiAKS Green can be used to obtain precise information on the H+ distribution at various compartments of the live cells.
  PubDate: 2022-09-03
A Broadband Achromatic Dielectric Planar Metalens in Mid-IR Range
- Abstract: Abstract Metalens are planar lenses composed of the subwavelength arrays, which have unconventional and versatile functionalities to manipulate the light fields compared with the traditional lens. It is noted that the most metalens are designed in a monochromatic mode in the visible or mid-infrared range (mid-IR), however, the broadband range is needed in many practical applications, such as spectroscopy, sensing, and imaging. Here, we design and demonstrate a broadband achromatic dielectric metalens in the mid-IR range of 4 µm–5 µm for near diffraction-limited (1.0λ) focusing. The broadband achromatic propagation and focusing of the metalens are designed and simulated by constructing and optimizing the phase profile. The Pancharatnam-Berry (P-B) phases of all the elements contribute to the main phase increment of the whole phase profile of the metalens. The additional phase is constructed and optimized by using the random search algorithm to obtain the optimized size of all the elements. The focusing efficiency of the achromatic metalens is also optimized and averaged as the result of phase optimization within a wide band for the building elements, while it is lowered comparing with the regular metalens without broadband achromatic designing. Using this combined designing approach, various flat achromatic devices with the broadband metalens can find a new way for full-color detection and imaging.
  PubDate: 2022-09-03
Demonstration of a ZnO-Nanowire-Based Nanograting Temperature Sensor
- Abstract: Abstract In this study, we experimentally demonstrate a miniature fiber thermometer based on tip-integrated ZnO-nanowire-nanograting. The sensor has a diameter less than 1 µm and the length of the Bragg grating is sub-10 µm. The ZnO-nanowire-nanograting is sensitive to the environmental temperature change. Thus, the intensity of the light whose wavelength is in the rising or falling region of the nanograting spectrum will vary with the shift in wavelength due to change in temperature. Taking one wavelength (655 nm) in the rise linear region of the nanograting spectrum, a sensitivity of 0.066 nW/°C in the air is achieved experimentally. The proposed temperature sensor has the superiorities of compactness, stableness, and easy fabrication compared to regular fiber grating sensors, offering great potential for detecting inside minimal volume environments.
  PubDate: 2022-07-19
Actual Sensing Sensitivity and SNR Measurement of Optical Tweezers Based
on Coulomb Force Input
- Abstract: Abstract Sensing sensitivity is the key performance of optical tweezers. By adjusting the frequency and magnitude of an applied Coulomb force as an input of optical tweezers, we directly measured the sensitivity and signal-to-noise ratio (SNR) of a system and indirectly calculated the actual noise magnitude. Combined with an output filter, the relationship between the SNR and bandwidths was studied. We established the simulation model of a system using Simulink and simulated the relationship between the SNR and magnitude of the input forces and filter bandwidths. In addition, we built an experimental system to determine the relationship between the SNR and the magnitude of the input forces and filter bandwidths. The actual minimum detectable force was measured as 1.8275×10−17 N at a 1 Hz bandwidth. The experimental results were correlated with the simulation and theoretical results, confirming the effectiveness of the proposed method and demonstrating the high sensitivity of vacuum optical tweezers as mechanical sensors. We proposed a novel method of calibration and measurement of system sensing parameters by applying an actual force that was more direct and precise than the theoretical calculation method that requires accurate fitting parameters, such as the particle radius and density. This method can be employed to analyze the system noise and phase characteristics to confirm and improve the real performance of the system.
  PubDate: 2022-07-15
Strain and Temperature Discrimination Based on a Mach-Zehnder
Interferometer With Cascaded Single Mode Fibers
- Abstract: Abstract An in-fiber Mach-Zehnder interferometer is proposed for the discrimination of strain and temperature. The sensor is based on two cascaded standard single mode fibers using three peanut tapers fabricated by simple splicing. The cascaded structure excites more frequency components, which induce four sets of interference dips in the transmission spectrum. One set of the spectrum dips have different sensitivities to temperature and strain from those of the other three. The sensor can discriminate strain and temperature by monitoring the wavelength shifts of two spectrum dips. Repeated experiments are taken both for strain and temperature increasing and decreasing scenarios. Experimental results show that Dip 1 has an average strain sensitivity of −0.911 pm/µε and an average temperature sensitivity of 49.98 pm/°C. The strain sensitivity for Dip 2 is negligible and its average temperature sensitivity is 60.52 pm/°C The strain and temperature resolutions are ±3.82 µε and ±0.33 °C.
  PubDate: 2022-07-14
D-Shaped Tellurite Photonic Crystal Fiber Hydrogen and Methane Sensor
Based on Four-Wave Mixing With SPR Effect
- Abstract: Abstract A new D-shaped tellurite photonic crystal fiber sensor based on the four-wave mixing (FWM) effect with the surface plasmon resonance (SPR) effect is designed and optimized. The substrate of the D-shaped photonic crystal fiber (D-PCF) is tellurite glass, and the polished surface is plated with the gold film and hydrogen gas-sensitive film. An air hole of the inner cladding, which is plated with the gold film and methane gas-sensitive film, is selected as the second sensing channel to simultaneously measure the concentration of hydrogen and methane. Based on the four-wave mixing, the wavelength shifts of the Stokes and anti-Stokes spectra resulting from the variation of the gas concentration can be used to accurately detect the concentrations of methane and hydrogen. Meanwhile, it is found that the SPR effect can increase the wavelength shifts, which means the sensitivity of methane and hydrogen augment. After parameter optimization, the maximum sensitivities of methane and hydrogen are 4.03 nm/% and −14.19 nm/%, respectively. Both the linearities are up to 99.9%. The resolution of methane is 1.25×10−2% and hydrogen is 7.14×10−3%. Moreover, the fiber length of this sensor is only 20 mm, which is conducive to the construction of a compact or ultra-compact embedded FWM fiber sensor.
  PubDate: 2022-07-11