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The anisotropic magnetoresistance film is an important core material for developing the magnetic sensors. Here, Ta(5)/MgO(3)/NiFe(10)/MgO(3)/Ta(3) multilayers (in nanometer) were prepared by magnetron sputtering and further applied to construct a sensor element by combining with the Wheatstone bridge. The 1/f noise of the sensor element was greatly reduced by three orders of magnitude after annealing at 400 °C for 7200 s, which was mainly due to the significant microstructural changes during the annealing. However, when the sensor element was applied to detect the magnetic signal of a magnetic code disk with 512 N–S magnetic poles, the output voltage signal of the sensor displayed a large fluctuation of ± 0.05 V. In order to reduce the voltage fluctuation, a magnetic sensor chip by using a parallelly arranged multi-path Wheatstone bridges and auto-gain compensation structure was designed, and magnetic sensor elements and the high-performance computing drive module were prepared. The output voltage fluctuation of the magnetic sensor was reduced by about 90% and approached to ± 0.005 V. These findings provide an important basis for the practical application of NiFe-based magnetic sensing film materials.

In order to set up a reliable prediction system for the tumor grade and prognosis in glioma patients, we clarify the complicated crosstalk of Annexin A2 (ANXA2) with Glypican 1 (GPC1) and demonstrate whether combined indexes of ANXA2 and GPC1 could improve the prognostic evaluation for glioma patients. We found that ANXA2-induced glioma cell proliferation in a c-Myc-dependent manner. ANXA2 increased the expression of GPC1 via c-Myc and the upregulated GPC1 further promoted the c-Myc level, forming a positive feedback loop, which eventually led to enhanced proliferation of glioma cells. Both mRNA and protein levels of ANXA2 were upregulated in glioma tissues and coincided with the overexpression of GPC1. Besides, we utilized tissue microarrays (TMAs) and immunohistochemistry to demonstrate that glioma patients with both high expression of ANXA2 and GPC1 tended to have higher rate of tumor recurrence and shorter overall survival (OS). In conclusion, the overexpression of ANXA2 promotes proliferation of glioma cells by forming a GPC1/c-Myc positive feedback loop, and ANXA2 together with its downstream target GPC1 could be a potential “combination biomarker” for predicting prognosis of glioma patients.

Background Programmed cell death protein 1 (PD-1) blockade is a major advance in the treatment of malignancies, but there remain many problems in efficacy evaluation. The aim of this study was to determine whether dynamic monitoring of serum specific tumor markers (SSTMs) could predict the response to PD-1 blockade and prognosis in patients with malignancies. Methods The dynamic changes in SSTMs in 27 patients between January 1, 2018 and July 31, 2019 were analyzed retrospectively. The association between the SSTM response and the radiological response was evaluated using the χ2 test and Spearman’s correlation analysis. Kaplan-Meier estimates and the log rank test were used to explore the correlation of SSTM dynamics with progression-free survival (PFS) and overall survival (OS). Results In this study, 85.3% of patients with malignant tumors had detectable SSTM. According to the changes of SSTM within the first 12 weeks of treatment, the patients were divided into a tumor marker increased group and a tumor marker decreased group. The change in SSTM was strongly associated with the change in target lesions (χ2=15.326, P≤0.001), and there was a positive correlation between them (Pearson Correlation r=0.727, P

Hypertensive cardiac remodeling is a constellation of abnormalities that includes cardiomyocyte hypertrophy and death and tissue fibrosis. Adenosine is a long-known vasodilator, through interacting with its four cell surface receptor subtypes in cardiovascular system. However, it is unclear that whether adenosine A2A receptor (A2AR) activation is involved in the cardiac remodeling in hypertension. WT mice were utilized to induce DOCA-salt sensitive hypertension and received A2AR agonist CGS21680 or antagonist KW6002 treatment. Cardiac functional phenotyping measurement by echocardiography showed that CGS21680 improved cardiac dysfunction in DOCA-salt mice. Moreover, CGS21680 reduced cardiomyocyte hypertrophy, cardiac inflammation and fibrosis. However, iBAT depletion surgery induces dramatic cardiac remodeling in DOCA-salt mice, and the protective function of CGS21680 was blocked without intact iBAT. Mechanistically, A2AR agonist CGS21680 increased iBAT-derived fibroblast growth factor 21 (FGF21). Our data suggest that activation of A2AR could be a potential therapeutic strategy in preventing heart damage in hypertension.

Obesity-induced secretory disorder of adipose tissue–derived factors is important for cardiac damage. However, whether platelet-derived growth factor-D (PDGF-D), a newly identified adipokine, regulates cardiac remodeling in angiotensin II (AngII)–infused obese mice is unclear. Here, we found obesity induced PDGF-D expression in adipose tissue as well as more severe cardiac remodeling compared with control lean mice after AngII infusion. Adipocyte-specific PDGF-D knockout attenuated hypertensive cardiac remodeling in obese mice. Consistently, adipocyte-specific PDGF-D overexpression transgenic mice (PA-Tg) showed exacerbated cardiac remodeling after AngII infusion without high-fat diet treatment. Mechanistic studies indicated that AngII-stimulated macrophages produce urokinase plasminogen activator (uPA) that activates PDGF-D by splicing full-length PDGF-D into the active PDGF-DD. Moreover, bone marrow–specific uPA knockdown decreased active PDGF-DD levels in the heart and improved cardiac remodeling in HFD hypertensive mice. Together, our data provide for the first time a new interaction pattern between macrophage and adipocyte: that macrophage-derived uPA activates adipocyte-secreted PDGF-D, which finally accelerates AngII-induced cardiac remodeling in obese mice.

Colorectal cancer has one of the highest mortality rates among malignant tumors, and most patients with non-microsatellite instability-high (MSI-H) colorectal cancer do not benefit from targeted therapy or immune checkpoint inhibitors. Identification of immunogenic neoantigens is a promising strategy for inducing specific antitumor T cells for cancer immunotherapy. Here, we screened potential high-frequency neoepitopes from non-MSI-H colorectal cancer and tested their abilities to induce tumor-specific cytotoxic T cell responses. Three HLA-A2-restricted neoepitopes (P31, P50, and P52) were immunogenic and could induce cytotoxic T lymphocytes in peripheral blood mononuclear cells from healthy donors and colorectal cancer patients. Cytotoxic T lymphocytes induced in HLA-A2.1/Kb transgenic mice could recognize and lyse mutant neoepitope-transfected HLA-A2+ cancer cells. Adoptive transfer of cytotoxic T lymphocytes induced by the peptide pool of these three neoepitopes effectively inhibited tumor growth and increased the therapeutic effects of anti-PD-1 antibody. These results revealed the potential of high-frequency mutation-specific peptide-based immunotherapy as a personalized treatment approach for patients with non-MSI-H colorectal cancer. The combination of adoptive T cell therapy based on these neoepitopes with immune checkpoint inhibitors, such as anti-PD-1, could provide a promising treatment strategy for non-MSI-H colorectal cancer.

Obesity increases the risk of vascular diseases, including aortic aneurysm (AA). Perivascular adipose tissue (PVAT) surrounding arteries are altered during obesity. However, the underlying mechanism of adipose tissue, especially PVAT, in the pathogenesis of AA is still unclear. Here we showed that angiotensin II (AngII) infusion increases the incidence of AA in leptin-deficient obese mice (ob/ob) and high-fat diet–induced obese mice with adventitial inflammation. Furthermore, transcriptome analysis revealed that platelet-derived growth factor-D (PDGF-D) was highly expressed in the PVAT of ob/ob mice. Therefore, we hypothesized that PDGF-D mediates adventitial inflammation, which provides a direct link between PVAT dysfunction and AA formation in AngII-infused obese mice. We found that PDGF-D promotes the proliferation, migration, and inflammatory factors expression in cultured adventitial fibroblasts. In addition, the inhibition of PDGF-D function significantly reduced the incidence of AA in AngII-infused obese mice. More importantly, adipocyte-specific PDGF-D transgenic mice are more susceptible to AA formation after AngII infusion accompanied by exaggerated adventitial inflammatory and fibrotic responses. Collectively, our findings reveal a notable role of PDGF-D in the AA formation during obesity, and modulation of this cytokine might be an exploitable treatment strategy for the condition.

The abnormally hyperphosphorylated tau is thought to be implicated in diabetes-associated cognitive deficits. The role of mammalian target of rapamycin (mTOR) / S6 kinase (S6K) signalling in the formation of tau hyperphosphorylation has been previously studied. Caveolin-1 (Cav-1), the essential structure protein of caveolae, promotes neuronal survival and growth, and inhibits glucose metabolism. In this study, we aimed to investigate the role of Cav-1 in the formation of tau hyperphosphorylation under chronic hyperglycemic condition (HGC). Diabetic rats were induced by streptozotocin (STZ). Primary hippocampal neurons with or without molecular intervention such as the transient over-expression or knock-down were subjected to HGC. The obtained experimental samples were analyzed by real time quantitative RT-PCR, Western blot, immunofluorescence or immunohistochemisty. We found: 1) that a chronic HGC directly decreases Cav-1 expression, increases tau phosphorylation and activates mTOR/S6K signalling in the brain neurons of diabetic rats, 2) that overexpression of Cav-1 attenuates tau hyperphosphorylation induced by chronic HGC in primary hippocampal neurons, whereas down-regulation of Cav-1 using Cav-1 siRNA dramatically worsens tau hyperphosphorylation via mTOR/S6K signalling pathway, and 3) that the down-regulation of Cav-1 induced by HGC is independent of mTOR signalling. Our results suggest that tau hyperphosphorylation and the sustained over-activated mTOR signalling under hyperglycemia may be due to the suppression of Cav-1. Therefore, Cav-1 is a potential therapeutic target for diabetes-induced cognitive dysfunction.

To investigate the osteoinductive mechanism triggered by hydroxyapatite/&beta, tricalcium phosphate (HA/&beta, TCP) biomaterials in mice which keep exercising. Methods: The HA/&beta, TCP biomaterials were implanted in the muscle of bilateral thighs (non-osseous sites) of eighty Balb/C mice. All animals were then randomly divided into 4 groups (n = 20). In group 1 (negative control group), the mice were fed routinely. In group 2 (running group), all mice were put on a treadmill which was set to a 60-degree incline. The mice ran 20 min thrice each day. A 5-minute break was included in the routine from day three onwards. In group 3 (weight-bearing group), all mice underwent weight-bearing running. The mice in this group performed the same routine as group 2 while carrying 5 g rubber weights. In group 4 (positive control group), dexamethasone was injected in the implanted sites of the biomaterials from the day of the operation. All mice were injected once per week and received a total of 8 injections. One and eight weeks after surgery, the blood serum was collected to detect inflammatory and immunological factors by ELISA. In addition to this, biomaterial specimens were obtained to observe inflammatory and osteogenic levels via histological staining and to facilitate analysis of the osteogenic mechanism by Western Blot. Results: The inflammation indexes caused by surgery were alleviated through running or weight-bearing running: The tumor necrosis factor-&alpha, (TNF-&alpha, ) and interleukin-6 (IL-6) levels were significantly reduced in groups 2 and 3 at week 8. Exercise also enhanced the secretion of interferon-&gamma, (IFN-&gamma, ) in mice, this can strengthen their immunity. The new bone tissues were observed in all groups, however, the area percentage of new bone tissues and the number of osteoblasts were highest in the weight-bearing group. Furthermore, the key proteins of wingless/integrated (Wnt) signaling pathway, Wnt1, Wnt3a, and &beta, catenin, were up-regulated during osteoinduction. This up-regulation activated runt-related transcription factor-2 (Runx2), increased the expression of osteopontin (OPN) and osteocalcin (OCN). Conclusion: Weight-bearing exercise can promote the bone and bone marrow formation through the Wnt signaling pathway: Observations documented here suggest that the proper exercise is beneficial to the recovery of bone damage.

Aims Aging is a risk factor for cardiovascular diseases and adaptive immunity has been implicated in angiotensin (Ang) II-induced target organ dysfunction. Herein, we sought to determine the role of T-cell senescence in Ang II-induced target organ impairment and to explore the underlying mechanisms. Methods and results Flow cytometric analysis revealed that T cell derived from aged mice exhibited immunosenescence. Adoptive transfer of aged T cells to immunodeficient RAG1 KO mice accelerates Ang II-induced cardiovascular and renal fibrosis compared with young T-cell transfer. Aged T cells also promote inflammatory factor expression and superoxide production in these target organs. In vivo and in vitro studies revealed that Ang II promotes interferon-gamma (IFN-γ) production in the aged T cells comparing to young T cells. Importantly, transfer of senescent T cell that IFN-γ KO mitigates the impairment. Aged T-cell-conditioned medium stimulates inflammatory factor expression and oxidative stress in Ang II-treated renal epithelial cells compared with young T cells, and these effects of aged T-cell-conditioned medium are blunted after IFN-γ-neutralizing antibody pre-treatment. Conclusion These results provide a significant insight into the contribution of senescent T cells to Ang II-induced cardiovascular dysfunction and provide an attractive possibility that targeting T cell specifically might be a potential strategy to treat elderly hypertensive patients with end-organ dysfunction.

To investigate the diagnostic value of multimodal ultrasound imaging composed of conventional ultrasonography (US), contrast-enhanced ultrasonography (CEUS), and shear wave elastography (SWE) for liver tumors. Between October 2017 and October 2019, US, CEUS, and SWE examinations of a total of 158 liver tumors in 136 patients at The First Affiliated Hospital of Nanchang University were performed. The histopathological or imaging diagnostic results were used as controls to evaluate the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of US, CEUS, SWE, and multimodal ultrasound imaging, which combines these 3 modes, in the differential diagnosis of benign and malignant liver tumors. Among the 158 tumors, there were 64 benign tumors, including 55 cases of hepatic hemangioma, 3 cases of focal nodular hyperplasia of the liver, 4 cases of hepatic cyst, and 2 cases of focal nonuniform distribution of fat in the liver. There were 94 malignant tumors, including 32 cases of hepatocellular carcinoma, 22 cases of intrahepatic cholangiocellular carcinoma, 29 cases of metastatic liver cancer, and 11 cases of dysplastic nodules in cirrhotic liver. In the diagnosis of benign and malignant liver tumors, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 82.56%, 68.06%, 75.96%, 75.53%, and 76.56% for US; 92.39%, 86.36%, 89.87%, 90.43%, and 89.06% for CEUS; 87.14%, 76.81%, 82.91%, 82.98%, and 82.81% for SWE; and 97.85%, 95.38%, 96.83%, 96.81%, and 96.88% for multimodal ultrasound imaging, respectively. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were all significantly higher for multimodal ultrasound imaging than those values for US, CEUS, and SWE (all P

The authors deliver a complete overview of fiber-optic Fabry-Perot (FFP) sensing technology, integrating the knowledge and tools of multiple fields including optics, sensing, micromachining, instrumentation, physics, and materials science. The main chapters discuss operating principles, microstructures, fabrication methods, signal demodulation, and instrumentation. This treatment spans the full range of structures (intrinsic/extrinsic, multimode fiber vs single-mode fibers), as well as advanced micromachining technologies and major interrogating and multiplexing methods for the formation of multi-point, quasi-distributed sensing networks. Readers will also gain a summary of state-of-the-art applications in oil, gas, and electricity industries, aerospace technology, and biomedicine. Yun-Jiang Rao is Dean of the School of Communication & Information Engineering, and Director of the Key Lab of Optical Fiber Sensing & Communications at the University of Electronic Science and Technology of China. Zeng-Ling Ran and Yuan Gong are both associate professors at the Optical Fiber Technology Research Laboratory of the University of Electronic Science and Technology of China.

With development of network and communication technology, cable network on university campus brings much convenience for teaching and research work. But for mobility and flexibility, it has obvious shortcoming. Wireless network can overcome these drawbacks and has been applied in university campus. In this paper, we present the advantages of wireless network and propose the design standards, construction and security measures for wireless network on university campus.

Recent progress in using excimer and femtosecond lasers to fabricate functional fiber-optic sensing devices is reviewed extensively in this paper. The application of femtosecond lasers is to fabricate fiber gratings and in-line fiber-optic interferometers for measurements of strain, temperature and refractive index. The application of 157 nm excimer lasers is to create fiber gratings and in-line fiber interferometers for measurements of strain, acceleration, pressure, temperature and refractive index. Compared with conventional optical fiber sensors, these novel micro optical fiber sensors fabricated by laser-micromachining have outstanding advantages, such as fast and direct formation, easy mass-production with ultralow-cost, good reproducibility, excellent optical performance, low temperature cross-sensitivity, etc., which pave a way to form a new generation of miniature fiber-optic sensors for many applications.

Perivascular adipose tissue (PVAT)-derived adiponectin (APN) is a secreted adipokine that protects against hypertension-related cardiovascular injury. However, the regulation of APN expression in hypertension remains to be explored. In this study, we demonstrated that down-regulation of APN was associated with complement activation in the PVAT of desoxycorticosterone acetate (DOCA)-salt hypertensive mice. Complement 3-deficient hypertensive mice were protected from ANP decrease in the PVAT. APN deficiency blockaded the protective effects of complement inhibition against hypertensive vascular injury. Mechanistically, complement 5a (C5a)-induced TNF-α secretion from macrophages is required for inhibiting APN expression in adipocytes. Macrophage depletion reversed C5a agonist peptide-induced TNF-α up-regulation and APN down-regulation in the PVAT of DOCA mice. Moreover, we detected increased macrophage infiltration and C5a expression associated with decreased APN expression in adipose tissue from patients with aldosterone-producing adenoma. These results identify a novel interaction between macrophages and adipocytes in the PVAT, where complement-mediated inhibition of APN acts as a potential risk factor for hypertensive vascular inflammation.-Ruan, C.-C., Ma, Y., Ge, Q., Li, Y., Zhu, L.-M., Zhang, Y., Kong, L.-R., Wu, Q-H., Li, F., Cheng, L., Zhao, A. Z., Zhu, D.-L., Gao, P.-J. Complement-mediated inhibition of adiponectin regulates perivascular inflammation and vascular injury in hypertension.

A back analysis procedure synthetically using parameters sensitivity analysis based on orthogonal design variance analysis, support vector regression modeling of nonlinear relation between mechanical parameters and displacement, and a hybrid optimization algorithm of particle swarm optimizer (PSO) and differential evolution (DE), was proposed. Optimum values of elasto-plastic mechanic parameters of rock mass were identified using the back analysis procedure and the measured displacement data. Assigning to the numerical model the optimum values of parameters, numerical simulation of powerhouse construction process was carried out to investigate the reliability of result of back analysis and the stability of powerhouse cavern. The result shows that calculated displacements are in good agreement with the measured, the powerhouse cavern is stable and has a considerable safety margin, and the existing support system can satisfy the need of local stability of powerhouse.

An inline fiber-optic micro-Fabry-Perot (MFP) cavity and a short fiber Bragg grating (SFBG) is overlapped to form an integrated MFP/SFBG sensor for simultaneous measurement of temperature and strain under high temperature (300 °C). The FP cavity is fabricated on a GeO 2 -doped photon sensitive fiber using the 157-nm laser micromachining technique and the SFBG is written at the same position of the MFP cavity using the standard 248-nm laser method. As the MFP cavity and SFBG have different sensitivity coefficients to temperature and strain, they can be utilized for realization of simultaneous measurement of dual parameters.

The Raman amplification can be employed to obtain the enhanced sensing performance in long-distance Brillouin optical time-domain analyzer (BOTDA) with higher temperature measurement accuracy over the whole sensing fiber. Theoretical investigation on the detected probe waveshape has been performed by using the probe-pump coupled equations combined with Raman amplification. The experimental characterization has been demonstrated to validate the theoretical prediction. The results show that, the 75 Km sensing distance can be achieved by utilizing the bi-directional Raman amplification with measurement accuracy of ±0.6°C over the whole sensing fiber. The larger Raman power and Brillouin pump power are helpful to improve the sensing signal-noise ratio (SNR). There exists an optimum range for the input probe power and the extinction ratio (ER) of input Brillouin pump pulse. The BOTDA with Raman amplification has considerable potentials to realize long- distance strain and temperature measurement for structural health monitoring and fire alarming, etc.

A Mach-Zehnder (M-Z) interferometer formed by two cascaded long-period fiber gratings (LPFGs) serving as ‘many’ multi-channel edge filters is used to detect the wavelength shift, induced by measurand of fiber Bragg grating (FBG) sensors with high optical SNR of >60 dB due to the use of a fiber ring laser, for the first time to our knowledge. Advantages of such a demodulation device are low-cost, compact, easy fabrication and implementation, good immunity of vibration and temperature, etc. In addition, in order to improve the resolution for dynamic strain measurement, a spectral analyzing algorithm called Music modern spectrum estimation is adapted. The experimental results show that a dynamic strain resolution of 0.1 μɛ/Hz 1/2 at 700 Hz is obtained, which is 10 times improvement in strain resolution when compared with conventional FFT method.

A novel bend-insensitive long-period fiber grating (LPFG) sensor written using focused CO 2 laser pulses is demonstrated, for the first time, to our knowledge. It is found that the central wavelength shift of such a LPFG is only −0.018 nm even for a curvature of 1.1 m −1 at the most bend-insensitive position of the LPFG. Experimental results show that the bend sensitivity of the central wavelength of the LPFG has a periodic distribution along its circular directions. Such a bend-insensitive sensor could be used to solve the problem of cross-sensitivity between bend and other measurands, such as temperature, strain or refractive index, which is an unsolved problem for LPFG sensors in practice. In addition, the bend sensitivity of the LPFG can be adjusted by selecting its circular positions.

In this paper, we report novel long-period fiber gratings (LPFGs) fabricated by using a new writing technique that is mainly based on the thermal shock effect of focused high-frequency CO2 laser pulses at several kHz. Several unique characteristics of these LPFGs, such as bend and transverse-load, etc., are observed by experiments, for the first time, to our knowledge. These unique features of the LPFGs are mainly due to the asymmetrical distribution of the refractive index on the cross-section of the LPFG induced by high-frequency CO2 laser pulses. Based on these novel LPFGs, an amplified spontaneous emission noise filter and a gain equalizer have been demonstrated for the noise figure reduction and the gain spectrum flattening of Er-doped fiber amplifiers (EDFAs), respectively. By means of the unique bending and loading features of the LPFG, two tunable gain equalizers have been demonstrated for dynamic gain flattening of EDFAs.

In this paper, we report a novel long-period fiber grating (LPFG) fabricated by using a new writing technique that is mainly based on the thermal shock effect of focused high-frequency CO/sub 2/ laser pulses at several kilohertz. A number of unique characteristics of such a LPFG, such as bend, torsion, and transverse load, are observed by experiments, for the first time, to our knowledge. Based on these unique features, a novel bend-insensitive LPFG sensor that could solve the problem of cross-sensitivity between bend and other measurands, a novel torsion sensor that can realize absolute measurement of twist rate, and a load sensor that can achieve simultaneous measurement of transverse load and temperature using a single LPFG element are proposed and demonstrated. These unique features of the LPFGs are mainly due to the asymmetrical distribution of the refractive index on the cross section of the LPFG induced by high-frequency CO/sub 2/ laser pulses.

The combination of Raman amplification and optical pulse coding (OPC) is proposed to reduce the frequency uncertainty in a long-distance Brillouin optical time-domain analyzer (BOTDA) under higher spatial resolution. The experimental characterization of temperature sensing with measurement accuracy ~ 1°C under ~ 2.5-m spatial resolution over a whole length of sensing fiber is demonstrated. The sensing fiber is composed of 49.6-km fiber at 10.8-GHz Brillouin frequency shift (BFS) and 25-km fiber at 11.005 GHz.

This paper proposes a novel method of multi-beam laser heterodyne measurement for Young modulus. Based on Doppler effect and heterodyne technology, loaded the information of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by mass variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain value of Young modulus of the sample by the calculation. This novel method is used to simulate measurement for Young modulus of wire under different mass by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.3%.

We investigate the formation of ripple and nanohole induced by femtosecond laser pulses on the surface of silicon. Periodic ripples aligned perpendicular to the direction of laser polarization has been observed. The period of the periodic ripples decreases with the increasing pulse number. Particularly aperiodic ripples with orientation parallel to the laser polarization are formed depend on the number of laser pulses and energy. The nanohole arrays are formed on the overlapped areas of periodic and aperiodic ripples. The interference between the surface scattered or excited wave and the laser itself is proposed to explain the decrease of ripple period.

A novel tunable gain equalizer based on the long-period fiber grating (LPFG) induced by high-frequency CO/sub 2/ laser pulses is demonstrated, for the first time, to our knowledge. Both the resonant wavelength and the resonant peak amplitude of the novel LPFG have a good linearity with temperature and transverse load, respectively. The wavelength and the peak amplitude of the gain equalizer can be tuned by the means of adjusting temperature and transverse load independently, showing that this tunable equalizer is a practical approach to realizing dynamic gain equalization in erbium-doped fiber amplifier systems.

The combination of Raman amplification and optical pulse coding (OPC) is proposed to reduce the frequency uncertainty in long-distance BOTDA under higher spatial resolution. The experimental characterization of 74.6Km temperature sensing with measurement accuracy ~1oC under ~2.5m spatial resolution over the whole length of sensing fiber is demonstrated. The performance comparisons of BOTDA with purely Raman amplification and combined Raman amplification with OPC are also displayed.

A novel fiber-optic phase-sensitive optical time-domain reflectometer (Φ-OTDR) distributed sensing system is proposed and demonstrated for long-distance intrusion monitoring. By using the bi-directional Raman optical amplification technology, even intrusion signal detection along the whole sensing distance of ~62km has been demonstrated, resulting in the longest and the most sensitive Φ -OTDR distributed sensing system reported so far, to the best of our knowledge. In addition, high-power single-mode fiber laser with ultra-narrow line-width and special optical fiber cable encapsulated by fiber reinforced plastic (FRP) are used to further enhance the intrusion detection sensitivity, respectively.

A novel tunable fiber ring laser configuration with combination of hybrid Raman amplification and erbium-doped fiber amplification (EDFA) is proposed for realizing ultra-long distance (300km) fiber Bragg grating (FBG) sensor system. The experimental results show that a 300 km transmission distance is achieved with an optical SNR of 4 dB, which is the longest FBG sensing distance, to the best of our knowledge.

An in-fiber Bragg grating (FBG) dynamic strain sensing system based on a fiber ring laser configuration and the Eigenvector spectrum analysis method, is proposed and demonstrated. An ultrahigh dynamic strain resolution of 5x10 -5 ne /Hz 1/2 is achieved due to both the use of the supper white-noise suppression ability of the advanced spectrum analysis method and the high optical signal-to-noise ratio (SNR) (~65dB) of the sensing signal generated by the fiber ring laser scheme. This is the highest dynamic strain resolution achieved so far for a single FBG sensor at frequency of

We demonstrate experimentally the light coupling effects between two parallel CO(2)-laser written long-period fiber gratings. For gratings written in standard single-mode fibers, the coupling efficiency depends strongly on the fiber orientation with the strongest coupling obtained when the exposed sides of the fibers face each other, while for gratings written in boron-doped fibers, the coupling efficiency is independent of the fiber orientation. We achieve a peak coupling efficiency of approximately 86% with gratings written in boron-doped fibers by using a suitable surrounding refractive index and offset distance between the two gratings. Our results suggest the possibility of realizing efficient broadband all-fiber couplers with CO(2)-laser written long-period fiber gratings.

A novel tunable fiber ring laser configuration with multi-stage hybrid Raman/EDF amplification is first proposed and demonstrated for realizing an ultra-long-distance (~100 km) fiber Bragg grating (FBG) sensing system with a high optical SNR of >50 dB.

A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

A novel tunable fiber ring laser configuration with hybrid Raman/EDFA configuration is first proposed and demonstrated for realizing high optical SNR of ~60dB, long-distance of ~50km, fiber Bragg grating (FBG) sensing systems.

In this paper, a hybrid Raman and Erbium-doped fiber amplifier (Raman/EDFA) is first proposed for enhancementof the performance of long-distance fiber Bragg grating (FBG) sensor systems. The Raman fiber amplifier is used for achieving low-noise amplification of FBG signals while the EDFA arranged remotely is used for both the compensation of the fiber loss due to long-distance transmission and the illumination of remotely-located FBGsensors as a broadband source by using the residual Raman pump power to generate ASE light and by amplifyingthe transmission light of the FBGs located before the EDFA. Such a sensor system adopts the advantages of thelow noise feature ofthe distributed Raman amplifier and the high small-signal gain ofthe EDFA. Experimentalresults show that the performance of the sensor system has been improved significantly. A signal-to-noise ratio (SNR) of l3dB has been achieved for a 50km transmission distance, which is l0dB higher than that without amplification.

In this letter, we present a novel sensor approach allowing fast measurement of temperature. It consists of a chirped fibre Bragg grating (CFBG) and an extrinsic Fabry-Perot interferometric sensor (EFPI) in series. Both EFPI and CFBG are well integrated to provide local strain and temperature information respectively, using wavelength-division-multiplexed (WDM) technique. As the wavelength-shift of the CFBG is detected via intensity variation, the speed for temperature measurement can be very high (

An alternative structure using third-order Raman amplification based on ultralong fiber lasers (UL-FLs) is investigated numerically to further improve the quasi-lossless transmission performance. The performance comparisons on flatness of signal distribution, optical signal–noise ratio (OSNR), and noise figure (NF) among first-order, second-order, and third-order Raman pumping based on UL-FLs are discussed numerically. The results display that the gain distribution is pushed more uniformly along UL-FLs using third-order Raman pumping, which is very useful to further extend the quasi-lossless midspan distance. For transparency transmission, enhanced quasi-lossless transmission could be achieved without sacrifice to OSNR and NF. We also analyze the transmission dynamics of loss-managed fundamental solitons for different pumping configurations. The amplifier span and transmission quality are improved considerably, even for lower dispersion lengths, by employing the proposed scheme.

The influence of the non-local effect on sensing performance in a long-distance Brillouin optical time-domain analyzer (BOTDA) based on bi-directional Raman amplification has been investigated theoretically. The system error induced by the non-local effect worsens with increased powers of probe wave and Raman pump. For smaller Brillouin pump power, the non-local effect is almost independent of Brillouin pump power. For larger Brillouin pump power, the non-local effect deteriorates gradually due to Raman gain saturation and cross-gain modulation (XGM). The purely backward pumping (relative to probe light) is preferable for non-local effect suppression. The frequency-division multiplexing (FDM) and time-division-multiplexing (TDM) technologies exhibit similar performance for suppressing the non-local effect under the same conditions. The sensing range near the far-end (relative to the Brillouin pump) should be appropriately shorter to minimize the non-local effect in FDM and TDM. The physical mechanisms of the non-local effect in long-distance BOTDA with Raman amplification are also shown.