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The initial characteristics of the surface layer following the quenching and tempering treatment of ultra-high-strength steel play a significant role in determining the subsequent precision machining. This study focus on investigating the influence of machining processes on the quenching and tempering surface layer. The machining processes affect both the oxidation of the quenching and tempering treatment and the development of a distinct preferred grain orientation. Gradual diminishment of surface abrasions leads to the transformation of the needle-like oxidation pattern into a layered oxidation structure. The preferred orientation of the grains prevents the grains from shear sliding, thereby enhancing the Taylor effect. Formation mechanisms of the microhardness and residual stress of the quenching and tempering surface layer induced by machining processes were also discussed and completely revealed. The microhardness is mainly attributed to the dynamic Hall-Petch effect, while plastic strain, dislocation energy storage, and phase transformation contribute to the residual stress changes. • Formation mechanisms of the quenching and tempering surface layer induced by machining processes were revealed. • Machined surface morphology affects preferred grain orientation preference and austenitization characteristics. • Microhardness of the surface layer induced by machining processes is mainly attributed to the dynamic Hall-Petch effect. [ABSTRACT FROM AUTHOR]

A novel micro-flank milling force prediction model is developed in this study by considering the deflection of tool and workpiece, tool run-out, and material strengthening effects during the flank milling of thin-walled parts. The model of the cutting tool applied in this study is closer to the actual structure and its deflection model is established based on Euler Bernoulli cantilever beam theory under mesoscale. The values of the workpiece deflection are obtained with an online Keyence LK-H020 laser sensor. The Johnson-Cook constitutive model is adopted to estimate the flow stress sJC, which takes in consideration the effects that strain-hardening, strain-rate, and thermal softening have on the flow stress. The mechanistic model is validated by a series of micro-thin-wall experiments with a two-flute KENNA micro-milling cutter as tool and Ti-6Al-4V titanium alloy as workpiece material. Experimental results illustrate that the proposed model performs well for the micro-flank milling forces in the x-direction, with an average error of 4.153%, while the error in the ydirection is slightly larger at 4.458%. [ABSTRACT FROM AUTHOR]

This paper developed a novel, simple-to-use method for detecting tool failure in cutting. An EEMD filtering and restructuring method is launched according to entropy and correlation of cutting force signal in turning high-strength and high-hardness materials using carbide cutting tools. Then, friction coefficient and mean power theories are adopted to characterize tool failure status using restructured cutting force signal. Finally, an automatic detector is proposed using CUSUM control chart to monitor tool chipping and tool wear failure in real time based on previous analysis and can be verified by semi-finishing experiment. Without any need of other sensor equipment and long computing time, the method can be reliable and simple to operate in detecting tool failure in real time. [ABSTRACT FROM AUTHOR]

Chatter is undesirable self-excited vibrations, which always lead to adverse effects during milling process. Selecting a reasonable combination of cutting parameters is an effective way to avoid chatter. Based on the mathematical model of milling process and the Floquet theory, the stable cutting area can be determined. The stability lobe diagrams (SLD) could be obtained by different interpolationmethods. To study the effect of higher order interpolation methods on the accuracy and efficiency of milling stability prediction, the state item, the time-delayed item, and the periodic-coefficient item of the state-space equation are approximated by different higher order interpolation methods, respectively. The calculations show that when the state item is approximated by the third-order Hermite interpolation polynomial, third-order Newton interpolation of the time-delayed item can improve the accuracy of SLD, while higher order interpolation of periodic-coefficient item has negative effect on improving effectiveness and efficiency compared to high-order interpolation of the state item and the time-delayed item. In order to obtain the SLD of milling process more accurately, an updated full-discretization milling stability prediction method which based on the third-order Hermite-Newton interpolation polynomial approximation is proposed in this paper. By dividing the tooth passing period equally into a finite set of time intervals, the third-order Hermite interpolation polynomial and the third-order Newton interpolation polynomial are utilized in each time interval to estimate the state item and the time-delayed item, respectively. The comparison of convergence rate of the critical eigenvalues and the SLD of the proposed method between the existing methods is carried out. The results indicate that the proposed method show a faster convergence rate than that of other methods, and its SLD is more close to the ideal ones with small number of time intervals. [ABSTRACT FROM AUTHOR]

In microdrilling, because of lower feed, the microdrill cutting edge radius is comparable to the chip thickness. The cutting edges therefore should be regarded as rounded edges, which results in a more complex cutting mechanism. Because of this, the macrodrilling thrust modeling is not suitable for microdrilling. In this paper, a mathematical modeling to predict microdrilling thrust is developed, and the geometric characteristics of microdrill were considered in force models. The thrust is modeled in three parts: major cutting edges, secondary cutting edge, and indentation zone. Based on slip-line field theory, the major cutting edges and secondary cutting edge are divided into elements, and the elemental forces are determined by an oblique cutting model and an orthogonal model, respectively. The thrust modeling of the major cutting edges and second cutting edge includes two different kinds of processes: shearing and ploughing. The indentation zone is modeled as a rigid wedge. The force model is verified by comparing the predicted forces and the measured cutting forces. [ABSTRACT FROM AUTHOR]

Accurate forecast of the sales growth rate plays a decisive role in determining the amount of advertising investment. In this study, we present a preclassification and later regression based method optimized by improved particle swarm optimization (IPSO) for sales growth rate forecasting. We use support vector machine (SVM) as a classification model. The nonlinear relationship in sales growth rate forecasting is efficiently represented by SVM, while IPSO is optimizing the training parameters of SVM. IPSO addresses issues of traditional PSO, such as relapsing into local optimum, slow convergence speed, and low convergence precision in the later evolution. We performed two experiments; firstly, three classic benchmark functions are used to verify the validity of the IPSO algorithm against PSO. Having shown IPSO outperform PSO in convergence speed, precision, and escaping local optima, in our second experiment, we apply IPSO to the proposed model. The sales growth rate forecasting cases are used to testify the forecasting performance of proposed model. According to the requirements and industry knowledge, the sample data was first classified to obtain types of the test samples. Next, the values of the test samples were forecast using the SVM regression algorithm. The experimental results demonstrate that the proposed model has good forecasting performance. [ABSTRACT FROM AUTHOR]

To further understand the effects of LSP on large components of high strength steel and provide improved solutions, this paper conducts research on effects of surface integrity on fatigue life in the LSP process with absorbent coating (LSPC), without absorbent coating (LSPN), without absorbent coating but with axial polishing (LSPP) respectively. The research also put a baseline specimens (BSL) before LSP for a comparison. Results show that average fatigue life in the LSPN process is 47.8% shorter than that of baseline specimens, and crack site area presents an obvious splitting-like tearing step. In the LSPC process, fatigue life is 31.7% longer than that of baseline specimens, and crack initiation site develops from surface to subsurface. In the LSPP process, the specimens show the longest fatigue life of 2.53 × 105cycles, with multiple fine microcracks developing simultaneously. Axial polishing removes ablative layer and tensile residual stress in the LSPN process and reduces dislocation pile-ups and refines grains in the LSPC process, resulting in a surface roughness of R a 0.61 μm, surface residual stress of −531MPa and microhardness of 405HV 0.025.Thus, the fatigue performances were found to be significantly affected by multiple surface integrity indicators induced by different LSP processes. In this paper, the effect of LSP on surface integrity on the subface and its influence on crack initiation and propagation have also been discussed, the crack initiation mechanisms in different processes were explained by using Murakami's K max equation. [ABSTRACT FROM AUTHOR]

Aeroengine blades are the power components most relevant to the energy conversion process. Due to the harsh working environment, the blades are seriously damaged after service, which affects their dynamic performance. The regrinding of damaged blades can extend their service life. However, the machining flexibility of the traditional grinding machine tool is insufficient to meet the needs of damaged blade repair, and the regrinding track of the blade cannot be directly generated by its theoretical geometric model. In order to solve the above problems, a robot regrinding scheme and trajectory planning method for damaged blades has been put forward. Based on the morphology measurement results of damaged blades, the point cloud reconstruction and regrinding trajectory research were carried out. The precision regrinding of damaged blades was realized. The comparison results of damaged blade morphology before and after regrinding indicate that the surface quality of the blade was improved significantly after regrinding. There are no obvious scratches, deep grooves, and large area adhesion on the repaired surface. The fractal dimension of the surface after regrinding is increased in different directions, which indicates that the surface structure characteristics after grinding are more fine. The average surface roughness of blades after robot regrinding is reduced from 2.67 to 1.59 μm. The profile error after robot regrinding is reduced from 0.35 to 0.16 mm. The research results provide a reference for the repair and manufacturing of blades. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced silicon carbide matrix (C/SiC) composites are typical difficult-to-cut materials due to high hardness and brittleness. Aiming at the problem of the serious high cutting force and poor surface quality in conventional milling (CM) C/SiC composite process, ultrasonic vibration-assisted milling (UVAM) and conventional milling tests with a diamond-coated milling cutter were conducted. The results showed that reducing the feed per tooth, cutting depth, or increasing the cutting speed can reduce the average cutting force, and increasing the ultrasonic amplitude, the average cutting force decreases first and then increases. With the assistance of ultrasonic vibration, the maximum reduction rates of average cutting forces Fx, Fy, and Fz were 43.7%, 29.16%, and 68.09%.The ultrasonic vibration assisting effect does not significantly improve the damage of materials such as fiber breakage during processing. The ultrasonic vibration assisting effect improves the quality of processing edges. It is found that reducing feed per tooth, cutting depth, or increasing cutting speed can reduce surface roughness and increasing the ultrasonic amplitude reduces the surface roughness first and then increases. On the whole, the surface roughness of C/SiC ultrasonic vibration milling is slightly smaller than that of conventional machining. [ABSTRACT FROM AUTHOR]

A highly sensitive waveguide temperature sensor based on asymmetric Mach–Zehnder interferometer was designed and experimentally demonstrated. The interferometer is based on the polymer/silica hybrid waveguide structure, and Norland Optical Adhesive 73 (NOA 73) was employed as the waveguide core to enhance the temperature sensitivity. The influence of the different length differences between the two interferometer arms on the sensitivity of the sensor was systemically studied. It is shown that the maximum temperature sensitivity of −431 pm °C−1 can be obtained in the range of 25 °C−75 °C, while the length difference is 92 μm. Moreover, the temperature sensitivity contributions from different core materials were also investigated experimentally. It is shown that the waveguide material and microstructure of the device have significant influences on the sensitivity of the waveguide temperature sensor. [ABSTRACT FROM AUTHOR]

• This article introduced the stiffness characteristics of the joint surface between the mechanical connection structures of the spindle-tool holder, tool holder-spring clamp, and spring clamp-tool of the spindle system in the robot machining system into the prediction of machining stability. • This paper proposed a method for establishing a tool tip frequency response prediction model for robot milling systems, which improves the accuracy of theoretical prediction of the tool tip dynamic characteristics of robot milling systems under different postures, Compared to the method of obtaining tool tip frequency response of robot milling system through experiments to support milling stability prediction, the method proposed in this paper effectively improves the efficiency of robot milling stability prediction. • The prediction results of the proposed tool tip frequency response prediction model were imported, and a two-degree-of-freedom chatter prediction model considering the regenerative effect is established, and the robot milling chatter is predicted considering redundant degrees of freedom. The accuracy of prediction results is verified by milling experiment. The change of tool tip frequency response caused by the posture dependence of robot dynamic is one of the key problems that make it difficult to accurately predict the milling stability of robot. In this paper, a tool tip frequency response prediction method considering the interface stiffness characteristics of spindle-tool system is proposed for stability prediction of robotic milling under the condition of posture variation. Firstly, the interface stiffness models of spindle-toolholder, toolholder-spring clip and spring clip-tool are established based on Yoshimura's unit area method. Then, The dynamics model for the robot body and the interface stiffness models for spindle-tool system are imported into the finite element analysis model of the spindle system, so that the prediction of the tool tip frequency response is realized by harmonic response analysis. Compared with the experimental results, the maximum error of the natural frequency was not more than 2 %, and the maximum error of the amplitude was not more than 12 %. Finally, the 2 DOF robot milling stability prediction model is established. Then the robot milling chatter is predicted considering redundant degrees of freedom from the perspective of regenerative chatter prediction theory, and the accuracy of prediction results is verified by milling experiment. [ABSTRACT FROM AUTHOR]

A β-TCP scaffold with a branched channel system was designed to create a novel micro-device that allowed culture perfusion and direct time observation of the cells attached. The scaffold was made by indirect solid free form fabrication (SFF) technology. The flow channel structure was exposed so that the perfusion of the mesenchymal stem cell (MSC) culture could be viewed directly. The cell-seeded scaffolds were continuously perfused for 7 days in the micro device;during this time, it was possible to observe the dynamic culture processes with cells adhering to the scaffolds and real time cell growth directly. This concept has great potential for use in bone tissue engineering and for versatile fabricationof enhanced scaffolds. [ABSTRACT FROM AUTHOR]

n view of the influence of cutting heat and cutting force on the machining precision of micro-machining, this paper carries out micro-milling temperature measurements and deformation measurement tests based on the theoretical model of temperature field distribution of workpiece and the simulation model of workpiece deformation, providing technical basis for the high-precision machining of precision micro-parts. A theoretical model for the description of the increase in the cutting temperature of the workpiece is established prior to using an inverse evaluation method for solving the heat source intensity iteratively. During the finite element analysis of the distribution of the temperature field and heat distortion, the process of the heat transfer is simplified as a process of applying a series surface heat source to workpiece. Besides, this paper carried on a series of micromilling experiments, used a fast-response thermocouple which has a property of self-renewal for the measurement of the change of the workpiece temperature, the response time of the applied thermocouple is within the magnitude of microsecond, and then, a high-frequency amplifier and an electric potential acquisition equipment were used to gain the transient temperature in the cutting area; meanwhile, a dynamometer is applied to measure the three-directional forces, and finally, the workpiece deformation would be measured by the Keyence microscope. Through the comparison of the simulated temperature and deformation with the experimental results, the simulation model showed considerable reliability. [ABSTRACT FROM AUTHOR]

A new machining method for lens molds using tilt electrical discharge milling (ED milling) has been experimentally investigated. Compared with the conventional ED milling, the tilt ED milling enables efficient enlargement of discharge gap by adjusting the tilt angles of the workpiece which results in efficient chip removal and burnish surface quality. On account of this method, micro lens craters were fabricated on the tungsten carbide (WC) and silicon carbide particulate reinforced aluminum metal matrix composite (SiCp/Al) at the optimized machining parameters under various tilt angles of the workpiece. The surface morphology and material removal rate were determined with a laser scanning microscope VK-X100 (KEYENCE, Japan). Experimental results present a 60% rise in surface quality at 25° in tilt ED milling. On the basis of electromagnetic effect, the machining mechanism is analyzed in detail in tilt ED milling for lens molds. [ABSTRACT FROM AUTHOR]

Single-point diamond cutting is an efficient method to generate the V-shape microgrooves, but the burr forms easily at the microgroove edge when cutting ductile material, especially at small (micron level) cutting depth, and the burr increases with the reduction in the cutting depth. In this paper, the effects of plastic side flow in micro cutting are taken into account to explain the formation of burrs in ultraprecision machining process. The edge radius of diamond tool is measured by scanning probe microscope (SPM), and the mechanism of the burr formation is revealed with considering the edge radius of diamond tool and the cutting depth in machining nickel phosphide (Ni-P). In this way, an approach to restrain the burr formation is established so as to generate fine microgrooves. [ABSTRACT FROM AUTHOR]

In order to promote the integrated application of the Internet of Things and cloud platform computing technology in intelligent manufacturing system, a cloud platform of cutting database was established in this paper. With the help of multi-sensor and distributed storage technology, mathematics model and data mining algorithm, functions of fast accessing and storing cutting data, intelligent modeling and analysis, efficient mining and optimizing processing parameters can be realized in the system, solving the key problems of analyzing cutting force and controlling surface quality in turning difficult-to-cut materials. Data equipment and users in the system were connected as a whole through wireless network, which can provide intelligent service of data querying, modeling, and optimizing through the cloud server. The study made up for the drawbacks in current intelligent database system such as oversimplified platform architecture, low level of intelligence, and low utilization of historical data, providing an efficient method of managing and applying big data in cutting process for the production system. [ABSTRACT FROM AUTHOR]

Proteinase A (PrA), the major protease in Saccharomyces cerevisiae, plays an essential role in zymogen activation, sporulation, and other physiological processes in vivo. The extracellular secretion of PrA often occurs during alcoholic fermentation, especially in the later stages when the yeast cells are under stress conditions, and affects the quality and safety of fermented products. Thus, the mechanism underlying PrA excretion must be explored to improve the quality and safety of fermented products. This paper briefly introduces the structure and physiological function of PrA. Two transport routes of PrA, namely, the Golgi-to-vacuole pathway and the constitutive Golgi-toplasma membrane pathway, are also discussed. Moreover, the research history and developments on the mechanism of extracellular PrA secretion are described. In addition, it is briefly discussed that calcium homeostasis plays an important role in the secretory pathway of proteins, implying that the regulation of PrA delivery to the plasma membrane requires the involvement of calcium ion. Finally, this review focuses on the effects of PrA excretion on wine making (including Chinese rice wine, grape wine, and beer brewage) and presents strategies to control PrA excretion. [ABSTRACT FROM AUTHOR]

Ultrahigh strength steel was a structural material with extremely high tensile, shear and yield strength. While, it was difficult to machining due to the excellent mechanical properties. There was serious problem in high quality and high efficiency machining of ultrahigh strength steel in actual production. In this paper, the effect of different turning parameters on cutting force, surface roughness, chip form and tool wear during dry turning of a typical ultrahigh strength steel were experimentally investigated, and the cutting parameters were optimized, then the empirical formulas of the cutting force and surface roughness Ra were also obtained. Both the cutting forces and surface roughness Ra were decreased as the increase of cutting speed, and increased as the feed rate and cutting depth. Within the selected range of machining parameters in the experiments, all the chips were serrated. The normal wear stage of the tool was not obviously, and the tool life was about 2000 s, which fulfilled the needs of actual production. This study gave experimental support for the parameter optimization during dry machining of ultrahigh strength steel, comprehensive considering processing efficiency, tool wear and machined surface quality. [ABSTRACT FROM AUTHOR]

Dynamic optical power distribution has great importance to network optimization. A three-dimensional (3-D) polymer thermo-optic switch is designed and fabricated to work at 650 nm. Two rectangular poly(methyl-methacrylate-glycidly-methacrylate) waveguides in neighboring and parallel layers couple with each other in a vertical direction. The lightwave is routed in two layers through a metal heater control. Waveguide configuration and relative position are optimized theoretically through beam propagation method calculations. The fabricated switch demonstrates an extinction ratio of 27.5 dB at a driving power of 57.7 mW. Measured rise time and fall time are 639.8 and 758.2 μs, respectively. Reliability characterizations within 125 days prove good operation stability at different extinction ratios. This work has potential in 3-D optical connections and visible light communication. [ABSTRACT FROM AUTHOR]

The inductively coupled plasma etching parameters for fabricating sensing windows of integrated Mach-Zehnder interferometer sensor based on polymers are systematically investigated. Under the optimum etching condition, we fabricate an improved sensing waveguide with three sensing surfaces, whose sensitivity can be enhanced by a factor of 3.5 in theory. Through precisely controlling the etching time, low propagation loss and high hydrophilicity are both achieved in the etched sensing waveguide. This optimizing approach along with rapid response and stable operation has rendered the MZ1 wave-guide sensor more competent to practical requirements of R1 sensing and biochemical sensing. [ABSTRACT FROM AUTHOR]

new strategy to tackle the orientation-relaxation of the chromophores was developed and used to prepare a film which was consisted of polymethyl methacrylate (PMMA) and photo-cross-linkable polyurethane oligomer (PU). The PU contained spindle-type chromophore and terminated with methacrylolyl groups as cross-linkable group. The chemical reaction process was characterized by infrared spectroscopy and the structure of reaction products were characterized by NMR spectroscopy. The surface morphology of the films was investigated by atomic force microscopy (AFM) images. The electro-optic (EO) coefficient of the prepared film was measured by using Teng-Man technique. The cross-linked films containing 15 wt% of the chromophore units displayed a high EO coefficient up to 41 pm/V. The 5% weight loss temperature was 228 °C for the film after photo-cross-linking. Compared with the uncross-linked films, their thermal and temporal stability were greatly improved. [ABSTRACT FROM AUTHOR]

A large number of air-discharge pits, varying in size and shape, are developed on the Yellow River delta. Their planar cross-sections are circular, sub-circular, elongated and frequently irregular and their spatial configurations may be in form of a shallow dish to root like or other, extremely irregular, shapes. They range in diameter from less than 1 cm to over 60 cm and their depth varies from less than 1 mm to more than 20 cm. They most commonly occur individually or in groups on the point bar.Our investigation indicates that the occurrence of the air-discharge pits is closely associated with the unique hydrological, channel and hydrodynamic conditions caused by the intermittent flow interruptions of the Yellow River and the fine sediments typical of the river course. During a Yellow River flow interruption, an underground air-saturation zone in the dry layer of the riverbed may be formed due to the lowering of the ground water level. When flooding originates from the up-stream section of the Yellow River, the water quickly inundates the channel and rapidly submerges the extremely dry river bed and point bar. As a result, due to the blocking effect caused by the silty sand and mud, preferential percolation occurs along the outer edge of the point bar and levee, trapping air in the process.The resulting air pocket and pressure capsule are enclosed in the air saturation zone, providing the source material required for the subsequent formation of air-discharge pits. The trapped air may also form a high pressure capsule caused by the slow downward percolation of the river water. The differential, relatively lower pressure on the point bar permits the trapped air to escape. Provided the air is discharged in a shallow body of water (<10 cm deep), the force of the agitated water caused by the bubble explosion may liquify the surface of sedimentary deposits and thus facilitate the transportation of the sediment by the current flow which eventually results in the formation of an air-discharge pit. [Copyright &y& Elsevier]

Background: Bone morphogenetic proteins (BMPs) are pleiotropic differentiation factors that regulate cell fate determination by orchestrating the activities of downstream signal transducers. Although BMP ligands can elicit signal transduction from heterodimeric combinations of several type-I and type-II receptors, cytoplasmic transducers of the BMP signal include only three known BMP-specific regulatory Smad proteins: Smad1, 5, and 8. In order to determine the combination of signals that regulate chondrogenesis by BMPs, we analyzed the functions of BMP Smad subtypes. Methods: Multipotential mesenchymal C3H10T1/2 cells and monopotential chondroprogenitor MC615 cells were placed in micromass culture in the presence or absence of BMP4. Chondrogenic differentiation was assayed by measuring So×9 and type-II collagen gene expression and by alcian blue staining. Transactivation of type-II collagen by regulatory Smads singly, or in combination with Smad4, which partners with regulatory Smads, was assayed by luciferase activity. Results: In the absence of BMP4, mesenchymal cells did not exhibit chondrogenic differentiation, whereas chondro-progenitor cells showed increased cartilage marker expression. In the presence of BMP4, the rate and extent of chon-drogenesis increased in a dose-dependent manner for both cell types. We further determined that Smad1 or Smad5, but not Smad8, synergized with Smad4 in the transactivation of the type-II collagen promoter in chondroprogenitor cells. In contrast, Smad8 and Smad4 presented modest synergy in mesenchymal cells. Conclusions:Taken together, our data suggest that uncommitted mesenchymal cells do not have the cellular competence to respond to the rate-limiting chondroinductive factor BMP. However, in chondroprogenitor cells, BMP stimulates differentiation through mechanisms mediated by Smad1 or Smad5 in combination with Smad4. Clinical Relevance: Our functional studies of these mesenchymal and chondroprogenitor cells will... [ABSTRACT FROM AUTHOR]

We propose a novel and efficient multi-functional optical fiber sensor system based on a dense wavelength division multiplexer (DWDM). This system consists of an optical fiber temperature sensor, an optical fiber strain sensor, and a 48-channel DWDM. This system can monitor temperature and strain changes at the same time. The ranges of these two sensors are from −20 °C to 100 °C and from −1000 to 2000 , respectively. The sensitivities of the temperature sensor and strain sensor are 0.03572 nm/°C and 0.03808 nm/N, respectively. With the aid of a broadband source and spectrometer, different kinds and ranges of parameters in the environment can be monitored by using suitable sensors. [ABSTRACT FROM AUTHOR]

In precision glass molding (PGM) of glass materials with a high melting point, heat treatment of nickel phosphorus (Ni–P) should be made in advance to eliminate mold deformation during the high temperature molding. During the process, crystallization occurs on the plating and crystalline Ni–P with a particular micro-machinability is generated. Burrs of large sizes with a fibrous structure are observed on the microgroove ridge during the study of the fly cutting microgrooving. The Poisson burr accumulation in each material removal period is considered as the reason for the burr formation and a model of the burr accumulation in fly cutting is established based on the concept of maximum effective cutting thickness. According to the model, a high feed rate leads to the restriction of burr formation while fracture pits tend to be generated on the microgroove ridge. The fracture pits caused by the brittle removal of the material could be eliminated through the feed rate adjustment of fly cutting. The optimal processing parameter is proposed in consideration of the burr formation restriction and the elimination of fracture pits. The efficiency of microgroove mold machining is significantly improved. A high-quality microgroove mold is fabricated and the serviceability of the mold is tested through a PGM experiment. [ABSTRACT FROM AUTHOR]

A polymer mode multiplexer based on asymmetric couplers is theoretically designed and experimentally demonstrated. The proposed X-junction coupler is formed by waveguides overlapped with different crossing angles in the vertical direction. A beam propagation method is adopted to optimize the dimensional parameters of the mode multiplexer to convert LP01 mode of two lower waveguides to LP11a and LP21a mode of the upper waveguide. The ultraviolet lithography and wet chemical etching are used in the fabrication process. A conversion ratio over 98% for both LP11a and LP21a mode in the wavelength range from 1530 to 1570 nm are experimentally demonstrated. This mode multiplexer has potential in broadband mode-division multiplexing transmission systems. [ABSTRACT FROM AUTHOR]

An optical waveguide displacement sensor according to core-cladding modes interference is theoretically proposed and experimentally demonstrated. Ultraviolet sensitive SU-8 polymer on silica is used as the guiding layer. It is covered by a 12 nm thick planar gold grating. The air gap sensing head which consists of the waveguide end and the single-mode fiber facet can realize the displacement detection by monitoring the wavelength dip shifting in transmission spectra. Cladding modes propagating in the exposed SU-8 can be effectively excited by the end-fire coupling because of the mode field mismatch between the SU-8 waveguide and lead-in fiber. A sinusoidal pattern transmission spectrum in C-band with the depth of over 14 dB can be observed due to the interference between the core and cladding modes. Peaks in the transmission spectrum vary continuously with the position offset of input fiber facet from the center of waveguide end. Both the sensitivity and the stability of sensing are enhanced by the introduction of nanometric gold gratings. The fabricated displacement sensor exhibits a high sensitivity of 2.3 nm μm−1, promising potentials for micromechanical processing and integrated optics application. [ABSTRACT FROM AUTHOR]

Optical loss induced by the arbitrary structure discontinuity in the Au stripe that supports long-range surface plasmon-polaritons (LRSPPs) propagation is investigated in this paper. A broad range of arbitrary gap sizes, 4 to 20 μm, is reported for 25 nm thick Au stripe with different widths embedded in 5 μm thick optically symmetric polymer SU-8. The simulations and experimental data find a high tunneling efficiency of the long-range mode power transmission of larger than 50% over a 10 μm gap at a wavelength of 1550 nm. Accordingly, a thermally activated in-line Mach–Zehnder interferometer switch based on the guiding of LRSPPs along Au stripe with gaps is designed and fabricated. Switching characteristics are analyzed upon heating one arm of the interferometer through the passage of current therein. The fabricated switch exhibits an extinction ratio of 17 dB with a driving power of 13 mW. The results prove that LRSPPs are insensitive to technological imperfections and waveguide interruptions, which is of benefit to active plasmonic device applications. [ABSTRACT FROM AUTHOR]

A heat-induced multimode interference (MMI) variable optical attenuator at 1310 nm wavelength, based on novel organic–inorganic hybrid materials is successfully designed and fabricated. The thermal stability and optical properties of the sol–gel materials are analyzed. The thermo-optic (TO) coefficient of the organic–inorganic hybrid material is obtained as −1.85 × 10−4 °C−1. The characteristic parameters of the waveguides and heat-induced electrodes are carefully designed and simulated. The propagation loss of a 4 μm-wide straight waveguide is 0.56 dB cm−1. The attenuation of the device is about −25 dB, and the applied electric power is 36.2 mW. The new material system and low-cost fabrication technique could be suitable for realizing large-scale photonic integrated circuits. [ABSTRACT FROM AUTHOR]