Side Polishing Research Articles

Temperature and RI sensing based on micro-structured optical fiber surface plasmon resonance

In this paper, we propose a surface plasmon resonance sensor based on micro-structured optical fiber capable of simultaneous sensing of a liquid refractive index and temperature. The fiber structure comprises four large air holes, with side polishing and rectangular groove processing on one side without air holes. Ag film and α-Fe2O3 film are coated inside the rectangular groove for refractive index sensing. Au film is coated on the inner walls of the two side air holes and filled with polydimethylsiloxane (PDMS) for temperature sensing. The results show that the sensor can achieve sensing of two parameters in two polarization directions. With a refractive index ranging from 1.35 to 1.42 and temperature ranging from 10°C to 100°C, the maximum refractive index sensitivity reaches 28225.7 nm/RIU and the maximum temperature sensitivity reaches −3.64nm/∘C. The sensor features simple structure, easy implementation, and high sensitivity, making it applicable in fields such as biosensing, chemical sensing, and environmental monitoring.

Tunable band-stop fiber filter based on laser-induced graphene metamaterial in THz frequency.

As an important device in the application of terahertz (THz) technology, a THz filter has broad application prospects in the fields of THz communication, imaging, and sensing. In this paper, a THz filter based on grating structure laser-induced graphene (LIG)/ side polishing terahertz fiber composite structure is proposed. In the experiment, we achieved the maximum Q factor of 23.83 at the central resonant frequency of 0.715 THz. By modifying the grating structure, a tunable operational span of 269 GHz was achieved, along with a tunable range of 21 GHz through laser stimulation. In testing, we found that LIG materials prepared with circular filling are more sensitive to relatively high-power pump lasers, while LIG samples prepared with line filling exhibit better linear response to laser power. Furthermore, the compact and highly integrated nature of the device suggests its broad potential utility in the realm of THz frequency selection.

Silver-TiO2 coated D-shaped photonic crystal fiber based SPR sensor for ultrasensitive refractive index detection: design and FEM analysis

Photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensors are emerging as a promising technology for ultrasensitive detection of various biological and chemical analytes. This paper presents a novel D-shaped PCF based SPR sensor, which has shown great potential for highly sensitive detection of refractive index (RI) changes. The D-shaped configuration is achieved through the polishing of the upper side of the PCF fiber. To enhance sensitivity, a 0.1 μm silver layer is strategically placed between the fiber and analyte, intensifying light–matter interactions. Additionally, a 0.05 μm titanium dioxide (TiO2) layer is employed not only to further boost sensitivity but also to shield the metal from oxidation, ensuring the longevity and stability of the sensor. The finite element method (FEM) is employed to optimize the structural parameters of the sensor design. The findings demonstrate that the proposed SPR sensor is sensitive to RI changes in the 1.31–1.35 range, achieving a peak wavelength sensitivity of 30000 nm RIU−1 and an amplitude sensitivity of −185.33 RIU−1. The sensor holds promise for diverse applications, including chemical and biological sensing, making it a versatile tool with promising implications for advancing sensing technologies in various domains.

Experimental research on the welding strength of PCBN and cemented carbide materials for cutting tools application

The PCBN tools has extensive applications in machining of various ferrous materials. The welding process is the necessary step to connect the PCBN tool nose and cemented carbide tool body. This paper conducted a series of welding experiments between PCBN and cemented carbide, the effect of filler alloy, surface treatment and heating parameters on the shearing strength has been tested and analyzed. The results showed that the addition of active element In in filler alloy can increase the shearing strength by 19.9%, and the side and bottom surface polishing treatment can increase the shearing strength by 124.1% and 96.8%. The adequate heating temperature and time to ensure full chemical metallurgical reaction is significant to obtain the higher shearing strength. At finally, the optimal welding parameters were used in PCBN tool application to improve the welding strength.

D-shaped microstructure fiber temperature sensor based on surface plasmon resonance

In order to solve the problems of oxidation of the metal film coated on the outer surface of the photonic crystal fiber and the low sensitivity of the sensor, a side polishing temperature sensor based on surface plasmon resonance is proposed. First, the sensor is modelled with a metal coating on the side of the optical fiber of the sensor, using a temperature sensitive liquid as the temperature sensing substance. Then, simulations were carried out to calculate the structural parameters of the optical fiber and the effect of the metal material on the resonant wavelength of the loss spectrum. By comparing the sensitive sensing of different metal films, gold was chosen as the surface plasma sensing material. Finally, the sensing characteristics of the sensor are simulated using the finite element method. The results show that when gold is used as the surface plasmon material, the wavelength range is 675–1117 nm, and the high sensitivity sensing in the temperature range of 0 °C–60 °C can be realized. When the temperature is 0 °C, the maximum spectral sensitivity is 24.6 nm °C−1. The designed sensors have excellent performance and can be widely used for temperature sensing.

Ultra-short bilayer graphene optical fiber intensity modulator based on silver-semicircular hybrid plasmonic waveguide

The intensity modulator is a key component in optical fiber communication. In this paper, an ultra-short graphene light intensity modulator based on hybrid plasmonic waveguide (HPW) array is proposed. Al2O3 embedded with double-layer graphene at a certain interval is placed on the side polishing surface of the microfiber Mach–Zehnder modulator (MZM), and the silver-semicircular array is placed on the surface of the transition material as hybrid plasmonic waveguide for the first time in all-fiber modulator. Analyzing by building a 3D model in finite difference time domain software, the hybrid surface plasmon polariton (HSPP) between silver-semicircles significantly enhances the subwavelength confinement and the light–graphene interaction. The modulation range of the real part of effective refractive index (Neff) can reach to 0.01984 by adjusting the Fermi level of graphene. Therefore, π phase change can be achieved only in a modulation length of 45 μm, and the insert loss can be controlled below 0.0159 dB/μm through the analysis of the imaginary part of the Neff, which also leads to a low total loss of 0.7155 dB. Owing to the excellent phase modulation efficiency, high extinction ratios of 39.39 dB and 47.77 dB can be reached for port 1 and port 2, respectively. Double-layer graphene forms the flat capacitor, which brings high modulation efficiency while achieving a high modulation bandwidth of 59.945 GHz. The application of HPW in graphene optical fiber modulator greatly improves the working efficiency, reduces the difficulty of integration, overcomes high insert loss, improves the extinction ratio, this modulator can be widely used in the future optical fiber communication system.

Infrared D-type photonic crystal fiber sensor for special drug detection and wide-range refractive index detection

In the field of drug inspection, the refractive indices (RIs) of many halogenated ethers and drugs are in the lower range; for example, the RI of anesthetic sevoflurane is approximately 1.27. Infrared spectral detection technology has significant advantages in the field of drug detection; to realize the RI sensing of such drugs in the infrared region, a D-shaped photonic crystal fiber sensor based surface plasmon resonance was investigated in this study. The side polishing adopted here can significantly shorten the distance between the core and metal layer, making the energy of the core easier to detect, reducing the difficulty of coating the metal layer, and improving the performance of the sensor. The structure is provided with two large-sized air holes on both sides of the fiber core, so that the sensor is suitable for sensing in the low RI range and has high wavelength sensitivity in the low RI range. The sensor works mainly in the infrared band, with a detection range of 1.20–1.34, maximum wavelength sensitivity of 24,000 nm/RIU, and resolution of 4.1667 × 10 − 6 R I U . The sensor has excellent performance and is easy to manufacture due to the simple structure; it has broad application prospects in low RI range detection fields such as biomedicine, drug detection, environmental monitoring, and water quality monitoring.

Design of photonic crystal fiber to excite surface plasmon resonance for highly sensitive magnetic field sensing.

To improve the sensing performance of optical fiber magnetic field sensor based on magneto-refractive effect, a D-shaped photonic crystal fiber-surface plasmon resonance (PCF-SPR) sensor based on magneto-refractive effect is proposed and its magnetic field sensing characteristics are investigated. The designed D-shaped PCF has a core-analyte-gold structure. Within the D-shaped PCF, the side polishing surface is coated with the gold film and the special hole is sandwiched between the core and the gold film. To realize the high magnetic field sensitivity for the fiber SPR magnetic field sensor, the special hole is filled with magnetic fluid (MF). In this paper, we analyze the mode transmission characteristics and magnetic field sensing characteristics of this fiber sensor by finite element method. We also obtain a general rule for the optimization of PCF-SPR sensors by analyzing the dispersion curves, the energy of the surface plasmon polariton mode and the core mode on the sensing performance of the designed fiber sensor. The maximum refractive index sensitivity and magnetic field sensitivity of the optimized fiber are 59714.3 nm/RIU and 21750 pm/mT (50-130 Oe), respectively. Compared with optical fiber magnetic field sensors based on magneto-refractive effect reported previously, the magnetic field sensitivity in this paper is nearly two orders of magnitude higher and it can initially achieve nT magnitude magnetic field resolution and testing capability. The proposed fiber sensor has the advantages of simple structure, easy production, high sensitivity, and strong environmental adaptability. It not only improves the sensing performance of optical fiber magnetic field sensors, but also provides an ideal alternative platform for biosensors like microfluidics because of its high refractive index sensitivity and the special structure.

Simplified process flow for the fabrication of PERC solar cells with ion implanted emitter

Ion implanted PERC cells have already achieved power conversion efficiencies of about 20.0%. The process flows reported in the literature for the ion implanted PERC cells with commonly utilized Al2O3/SiNx rear passivation stack, which has the benefit of being less sensitive to surface roughness than SiO2/SiNx stack passivation, notably suffer from the additional process steps such as single side polishing and single side protection. Here, we present a simplified process flow for the fabrication of ion implanted PERC cells having Al2O3/SiNx stack passivation at the textured rear surface without any rear side processing, leading to a power conversion efficiency of 20% at large area. In this context, we show the sensitivity of solar cell efficiency to firing peak temperature, implantation dose, and Al2O3 thickness. The results of the present research will provide a basis for high efficiency implanted PERC cells with significantly reduced workload and cost.

A High‐Sensitivity Refractive Index Sensor Based on an External Gold Coating of a Square‐Lattice Photonic Crystal Fiber

A high‐sensitivity square‐lattice photonic crystal fiber (PCF) refractive index (RI) sensor based on an external gold coating is proposed. This design eliminates the limitations of selective coating and liquid penetration in the micrometer holes, and avoids the side polishing of D‐type fibers. The effects of air hole diameter and gold film thickness on the sensing performance are studied in detail using the full vector finite element method (FV‐FEM). In addition, the sensing performance of the gold‐coated PCF under the optimized parameters is compared with that of PCF with the same air hole diameter and a gold grating. The results show that the proposed PCF has a higher structural tolerance to the air hole diameter, which improves the manufacturing feasibility. Moreover, the gold‐coated PCF has a maximum sensitivity of 31 000 nm RIU−1 and a resolution of 3.23 × 10−6 RIU in the RI measurement range of 1.34–1.49. The maximum sensitivity of the gold‐grating PCF with lower loss is 30 000 nm RIU−1 in the RI detection range of 1.38–1.46, and the resolution is 3.33 × 10−6 RIU. Low loss is beneficial for extending the length of the fiber, which is convenient for practical implementation. Thus, it has potential applications in biomolecular and biochemical analysis.

Refractive index sensing and filtering characteristics of side-polished and gold-coated photonic crystal fiber with a offset core

The transmission characteristics of a side-polished eccentric photonic crystal fiber (PCF) is studied by using the full-vector finite element method (FV-FEM). The proposed structure is composed of air holes similar to a U-shaped arrangement, and there is a small air hole between the side polishing plane and the core region to enhance the leakage of the evanescent field in the y polarization direction. It integrates refractive index (RI) sensing and polarization filtering. The RI sensing mainly works in the visible light band, while polarization filtering is suitable for the near-infrared band. The maximum sensitivity of the sensor is 12,500 nm/RIU, and the resolution is 8.0 × 10−6 RIU in the detection RI range of 1.35–1.39. By changing the external RI or the thickness of the gold-coated film, the bandwidth-tunable PCF polarization filter with excellent performance can be obtained. Therefore, the design of side-polished PCF will be of great significance to the development of integration and miniaturization of optical devices.

Evaluation of Tensile Shear Strength under Salt Spray Test on Dissimilar Metal Spot Welding of Aluminum Alloy and Galvannealed Steel Sheet

In order to reduce the weight of parts in the automobile and electronic industries, various research on dissimilar welding techniques of aluminum and steel is being carried out. Since dissimilar materials have different physical and electrochemical characteristics, joining through conventional fusion welding is challenging, and there is a high probability of a decrease in strength of the welded joints. To solve this problem, a mechanical fastening method is mainly applied to join dissimilar parts with different material properties, but this process has disadvantages in terms of productivity improvement and cost reduction because additional consumables, such as rivets, are required. In this research, we investigated the optimization of the weld bonding conditions of joints using epoxy-based adhesive bonding and DeltaSpot welding for Al/Fe dissimilar materials. For each experimental condition, the corrosion resistance and tensile shear strength of the welded joints were evaluated according to salt spray test times of 0 h, 640 h, 1280 h, and 1920 h. As a whole, as the salt spray test time increased, the tensile shear strength of the welded joints decreased. It was confirmed that weld bonding, after manual polishing of the aluminum side, resulted in the highest average tensile shear strength of 5.88 kN at 1920 h, which was an increase compared with other conditions.

Evolution of PERC from Al-BSF: optimization based on root cause analysis

Passivated emitter rear contact (PERC) solar cell involves upgraded adaptation of technology over the existing silicon wafer-based aluminium back surface field (Al-BSF) solar cell. The lower efficiency of Al-BSF is caused by a few drawbacks e.g. higher rear surface recombination and weaker electric field at the rear surface. These technical shortcomings can be mitigated by incorporating field-effect passivation (FEP) layer viz. aluminium oxide (Al2O3) at the rear surface with a capping layer of SiNX on it. Conventionally two new processing steps utilizing two expensive equipments, green laser (532 nm) for laser ablation of the FEP and SiNX capping layer stack at the rear surface and single side etcher for rear side polishing of wafer are used for manufacturing of PERC cells. In this paper, we have shown that instead of these two new expensive processing equipments we can use the IR laser (1024 nm) and RIE etcher, which are commonly available for Al-BSF manufacturing line, for the fabrication of PERC solar cells. Using p-type wafers of rather modest quality (minority carrier lifetime of ≥10 µs) we have demonstrated improvement of the efficiency from 18.71 to 19.62% and enhancements in VOC and JSC from 628 to 646 mV and 38.59 mA/cm2 to 39.82 mA/cm2, respectively. A thorough root-cause analysis has been carried out to optimize the two new approaches within the existing Al-BSF line for the fabrication of PERC solar cell.

Sodium nitrate sensor based on D-shaped fiber structure

Abstract This paper demonstrates a low-cost robust refractive index (RI) sensor based on a sensing structure realized with graphene-coated D-shaped fiber structure. The proposed sensing structure is of 5-dB insertion loss single mode fibers fabricated by means of side polishing; drop casting is used for the graphene coating that would act as a sensing layer to enhance the sensitivity of the sensing probe. Observations showed that the output power decreased from 7.17 dBm to 5.85 dBm with sensitivity of 0.223 %/dBm and linearity of 99 % as six different concentrations of sodium nitrate that varies from 1 to 7 % were tested on the sensor probe. These results came from the interaction of propagating light in the evanescent wave with the external changing environment. The resonant peak shifted to longer wavelength with increasing refractive index. The sensing structure was embedded onto a fiber ring laser as this combination offers high measurement resolution and increase their remote sensing capability.

Fabrication of diamond diffractive optics for powerful CO2 lasers via replication of laser microstructures on silicon template

New approach to fabricate diamond diffractive optical elements (DOEs) with continuous relief for powerful CO2 lasers is proposed and tested. It involves short-pulse laser microstructuring of a silicon wafer, which further is used as a substrate for polycrystalline diamond growth in a microwave plasma-assisted CVD process. After fine mechanical polishing of the growth side of the diamond film, the silicon substrate is removed via chemical etching. Two different DOEs providing close to 100% diffraction efficiency were fabricated with this technique: cylindrical Fresnel lens with kinoform surface profile and three-beam splitter with continuous microrelief. Optimization of the laser processing conditions has made possible to reduce the final roughness of the structured diamond surface to 200–400 nm depending on the local relief depth (0–7 μm). Both DOEs tested with a CO2 laser have demonstrated high transparency and diffraction efficiency, as well as low radiation scattering of the IR radiation at the surface irregularities.

Refractive Index Sensing Based on a Side-Polished Macrobend Plastic Optical Fiber Combining Surface Plasmon Resonance and Macrobending Loss

In this paper, we introduce a refractive index (RI) sensor based on the surface plasmon resonance (SPR) effect. A commercial plastic optical fiber (POF) is fabricated with a D-shaped macrobend structure by heat setting and side polishing techniques to expose the core and enhance the RI sensitivity. Gold is sputtered onto the polished surface of the POF, generating a film with a thickness of approximately 10 nm. When the RI of the environment changes, the propagation attenuation in the macrobend section and the SPR spectrum change simultaneously. Therefore, the RI can be determined by the dual mechanism of bending loss and spectral shift. The experimental results show that as the RI of the immersion liquid varies from 1.33 to 1.40, the sensing probe exhibits a bending loss change and a spectral shift. This result indicates that the sensitivities of the probe in regard to bending loss and SPR are 43 dB/RIU and 1570 nm/RIU, respectively.

Side-Polished DBR Fiber Laser with Enhanced Sensitivity for Axial Force and Refractive Index Measurement

A highly sensitive optical fiber sensor for the measurement of axial force and refractive index (RI) is presented. The optical sensor consists of a distributed Bragg reflector (DBR) based fiber laser, the laser cavity of the DBR is polished to D-shape by the wheel fiber polishing system. Birefringence has been introduced with side polishing of the fiber, and then, it is utilized for sensing applications. The working principle of the device is based on the principle of the change in beat frequency of the two orthogonal polarization modes of the DBR fiber laser with external perturbations. In this work, it has been shown that the dual polarization beat frequency can be used for RI-based measurement applications along with the measurement of the axial force. The sensitivity of the DBR fiber laser sensor with change in axial force is enhanced significantly with side polishing. Such a device is robust, simple in fabrication and most importantly low-cost interrogation techniques can be used for the detection purpose. A resolution of 5.6014 × 10–8 N has been achieved in case of recognition of axial force and 1.9259 × 10–5 RIU is the observable detection limit for the RI based measurement.

Beat frequency tuning in dual-polarization distributed feedback fiber laser using side polishing technique.

We propose and demonstrate a method for tuning the beat frequency of a dual-polarization distributed feedback (DFB) fiber laser via fiber side polishing. This process can significantly alter the birefringence in DFB fiber lasers. Beat frequency evolutions in DFB fiber lasers were investigated, and the experimental results showed that the beat frequency tuning was dependent on polished thickness, roughness, and direction. The abrasive paper with a grain size of 1.8 µm was adopted to fine-tune the beat frequency. It was found that the beat frequency of DFB fiber lasers shifted toward higher frequencies with increasing polished thickness. However, the beat frequency shifted toward lower frequencies using a secondary side polishing process in the direction orthogonal to the first polished surface. As a result, the beat frequency of the DFB fiber laser was tuned in a wide frequency range from 475.5 MHz to 2080.4 MHz, which corresponds to a birefringence change of 1.2 × 10-5. Side-polished DFB fiber lasers could provide a novel approach to frequency division multiplexing for a large number of fiber laser sensors.

Evanescent Wave Absorption Based Fiber Sensor for Measuring Glucose Solution Concentration

An optical fiber sensor based on evanescent wave absorption designed for measuring glucose solution consentration was proposed. The sensor was made to detect absorbance of various wavelength in the glucose solution. The sensing element was fabricated by side polishing of multimode polymer optical fiber to form a D-shape. The sensing element was immersed in different concentration of glucoce solution. As light propagated through the optical fiber, the evanescent wave interacted with the glucose solution. Light was absorbed by the glucose solution. The larger concentration the glucose solution has, the more the evanescent wave was absorbed in particular wavelenght. Here in this paper, light absorbtion as function of glucose concentration was measured as function of wavelength (the color of LED). We have shown that the proposed sensor can demonstrated an increase of light absorption as function of glucose concentration.

Determination of the profile of the worm-type tool

The cutting wedge of disk shaver at gear shaving has not fully satisfactory geometry: clearance The cutting wedge of the disk shaver when gear shaving is not fully geometrically satisfactory. The clearance on cutting edges are practically equal to zero. We would suggest this is the reason that the disk shavers machining of gear-wheels with large allowance is not possible. The construction of a worm-type tool is known also for clean machining of points of involute of gear-wheels made with continuous spiral cutting edges. The difference of this construction from the construction of N. Chemborisov is that a cutting wedge has the structurally made clearance α (Authors: N. Smorkalov, V. Skripin, V. Ptitcin, IU. Belugin). Polishing of side of coil is the most responsible and labor intensive operation when making a worm-type tool with the continuous spiral cutting edges of construction of N.Smorkalov and other.Dependences allowing to define the coordinates of key points of axial section of side of coil of the worm-type tool were obtained. These coordinates will allow to define the parameters of setting of abrasive disc in relation to the worm-type tool.