Formation of E-band luminescence-active centers in bismuth-doped silica fiber via atomic layer deposition.

In this study, a Si defect structure was added into the silica network in order to activate the bismuth and silica structure active center. TD-DFT theoretical simulations show that the Bi and Si ODC(I) models can excite the active center of the E-band at 1408 nm. Additionally, the Bi-doped silica fiber (BDSF) with improved fluorescence was fabricated using atomic layer deposition (ALD) combined with the modified chemical vapor deposition (MCVD) technique. Some tests were used to investigate the structural and optical properties of BDSF. The UV-VIS spectral peak of the BDSF preform is 424 cm-1, and the binding energy of XPS is 439.3 eV, indicating the presence of Bi° atom in BDSF. The Raman peak near 811 cm-1 corresponds to the Bi-O bond. The Si POL defect lacks a Bi-O structure, and the reason for the absence of simulated active center from the E-band is explained. A fluorescence spectrometer was used to analyze the emission peak of a BDSF at 1420 nm. The gain of the BDSF based optical amplifier was measured 28.8 dB at 1420 nm and confirmed the effective stimulation of the bismuth active center in the E-band.

Bandwidth extension to 1627†nm of over 20†dB gain in an erbium-doped silica fiber via two-photon absorption.

In this study, PbS/Er co-doped fibers (PEDFs) were fabricated by atomic layer deposition (ALD) combined with modified chemical vapor deposition (MCVD). A pumping scheme based on two-photon absorption at 1310 nm of PEDF is proposed for L + band amplification. Through the theoretical analysis, the local environment of Er3+ is changed due to the co-doping of PbS, which improves the two-photon absorption efficiency near 1300 nm. Compared with the 980 nm pump, the PEDFs excited by the 1310 nm pump show better amplification performance in the L + band. And in a bi-directional pumping system, PEDF achieves over 22 dB of gain in the whole L band. In particular, the bandwidth of over 20 dB gain was extended to 1627 nm with a noise figure as low as 4.9 dB. To the best of our knowledge, this is the first time that a high-gain bandwidth of L band amplification has been extended to 1627 nm. The results of unsaturated loss also show that PbS co-doping improves the two-photon absorption efficiency of PEDF to broaden the amplification bandwidth of L + band. These results demonstrate that an effective L + band amplification method is practically provided for future ultra-wideband optical communications.

Sub-kHz-linewidth continuous-wave single-frequency ring-cavity fiber laser based on high-gain Er: YAG crystal-derived silica fiber.

Throughout the development of single frequency fiber lasers (SFFLs), gain fiber is one of the most important components, which can greatly affect the quality of SFFLs. Here, we fabricated an Er: YAG crystal-derived silica fiber (EYDSF) using a CO2 laser-heating drawing technique, with a high gain coefficient of 1.74 dB/cm. Employing the EYDSF of only 10 cm as a gain medium, we constructed a continuous-wave ring-cavity SFFL with an all-fiber system. An ultra-narrow linewidth <660 Hz was achieved harnessing a homemade low-concentration Er-doped silica fiber as a saturable absorber. Importantly, the SFFL output power was up to 32.7 mW at 1560 nm. What's more, no multi longitudinal mode or mode hopping were found in 2 hours, and the fluctuation of power was <0.63% in 8 hours. Furthermore, the relative intensity noise was lower to -145 dB/Hz at frequencies over 1 MHz. The results indicate that the ring-cavity SFFL has desirable performance in output power, linewidth, stability and noise, which serves a prospective candidate applied to coherent optical communications, high-precision sensors, laser radars and other advanced fields.

Near 0.5†dB gain per unit length in O-band based on a Bi/P co-doped silica fiber via atomic layer deposition.

In this work, bismuth doped fiber (BDF) and bismuth/phosphosilicate co-doped fiber (BPDF) were fabricated by atomic layer deposition (ALD) combined with the modified chemical vapor deposition (MCVD). The spectral characteristics are studied experimentally and the BPDF has good excitation effect covering the O band. A diode pumped BPDF amplifier with the gain over 20 dB from 1298-1348 nm (50 nm) has been demonstrated. The maximum gain of 30 dB was measured at 1320 nm with a gain coefficient of around 0.5 dB/m. Furthermore, we constructed different local structures through simulation and found that compared with the BDF, BPDF has a stronger excited state and a greater significance in O-band. This is mainly because phosphorus (P) doping changes the associated electron distribution and forms the bismuth-phosphorus active center. The fiber has a high gain coefficient, which is of great significance for the industrialization of O-band fiber amplifier.

Voltage, thermal and magnetic field fiber sensors based on magnetic nanoparticles-doped photonic liquid crystal fibers.

In this article, highly sensitive voltage, thermal and magnetic field fiber sensors were obtained in magnetic nanoparticles-doped E7 liquid crystals filled into photonic crystal fibers (PLCF). The voltage and temperature sensitivity reached at 12.598 nm/V and -3.874 nm/°C, respectively. The minimum voltage response time is 48.2 ms. The phase transition temperature Tc of liquid crystal with magnetic dopant was reduced from 60 °C to 46 °C. The magnetic field sensor based on magnetic nanoparticles-doped PLCF were obtained with sensitivity of 118.2 pm/mT from 400 to 460 mT.

Comparison of anesthetic effects of different doses of alfentanil combined with ciprofol in elderly patients undergoing ERCP: a randomized controlled trial.

BACKGROUND AND OBJECTS: Patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) are often old and poor in physical fitness. The purpose of this study was to investigate the anesthetic effect of different doses of alfentanil combined with ciprofol in elderly patients undergoing endoscopic retrograde cholangiopancreatography (ERCP). METHODS: In this clinical trial, 137 patients, who were candidates for ERCP were randomly divided into three groups. Group A were given 0.15 µg/kg/min of alfentanil in maintenance stage, Group B were given 0.25 µg/kg/min and Group C were given 0.35 µg/kg/min. Mean arterial pressure (MAP), heart rate (HR), oxygen saturation (SpO2) of the patients at each time point including the entry into the operation room (T0), at the beginning of surgery(T1), 10 min after surgery(T2), 20 min after surgery(T3), 30 min after surgery(T4),endoscopy withdrawal (T5) were recorded. Adverse events(including respiratory depression, body movement and hypoxemia),the dosage of ciprofol, the time of operation time and awakening were recorded. RESULTS: Compared with Group A, MAP and HR in Group B and Group C was decreased during T1-T5 (P < 0.05). Compared with group B, MAP and HR in group C was decreased during T1-T5 (P < 0.05). Compared with Group A and Group C,the number of adverse reactions of Group B was decreased(P < 0.05). There was no statistical difference in surgical time among the three groups(P > 0.05),but a statistically significant difference in recovery time (P < 0.05). CONCLUSION: The adverse events of alfentanil 0.25µg/kg/min combined with ciprofol were low, and the anesthetic effect was the best.

The stiffness of transplanted kidneys changes with time after renal transplantation.

BACKGROUND: Kidney transplantation is one of the most effective ways to treat end-stage kidney disease. However, 5000 renal transplant recipients start or restart dialysis because of chronic allograft nephropathy (CAN) every year in the United States. Detecting changes in the stiffness of transplanted kidneys can help diagnose transplanted kidney disease. PURPOSE: To explore changes in the stiffness of transplanted kidneys after renal transplantation using shear wave elastography (SWE). MATERIAL AND METHODS: This study conducted consecutive follow-up observations on 10 patients after kidney transplantation. SWE examination was performed in the first week, second week, first month, second month, third month, fourth month, fifth month, and sixth month after surgery. This study also analyzed the graft stiffness of 86 patients with stable renal function recovery one month after surgery. RESULTS: The results show that there is a change in the stiffness of the transplanted kidney over time after renal transplantation. It decreases rapidly within one month after renal transplantation and tends to be stable after one month. The mean renal cortical and pyramidal stiffness of patients with stable renal function were 28.48 ± 4.27 kPa and 21.97 ± 3.90 kPa, respectively. CONCLUSION: Consecutive stiffness measurement of transplanted kidneys is an effective method for monitoring the function of transplanted kidneys. According to the change in transplanted kidney stiffness, we can designate a more scientific review plan to determine the functional status of the transplanted kidney.

Oxycodone versus morphine for analgesia after laparoscopic endometriosis resection.

BACKGROUND: The objective of this study was to compare the analgesic potency of oxycodone versus morphine after laparoscopic deep infiltrating endometriosis resection. METHODS: Fifty patients undergoing laparoscopic deep infiltrating endometriosis resection were randomized to receive oxycodone or morphine intravenous-PCA after surgery. The primary outcome was opioid consumption during the 24 h after surgery. Secondary outcomes included time to first request for analgesia, the number of bolus, pain, sedation, nausea, vomiting, respiratory depression, and bradycardia. The prominent pain that caused patients to press the analgesic device was also recorded. RESULTS: Oxycodone consumption (14.42 ± 2.83) was less than morphine consumption (20.14 ± 3.83). Compared with the morphine group, the total number of bolus (78 vs 123) was less and the average time to first request for analgesia (97.27 ± 59.79 vs 142.17 ± 51) was longer in the oxycodone group. The incidence of nausea was higher in the morphine group than in the oxycodone group at 0-2 h (45.45% vs 17.19%), 2-4 h (50% vs 17.19%),12-24 h (40.91% vs 13.04%) and 0-24 h (39.17% vs 19.13%). The overall incidence of vomiting was higher in the morphine group (27.27% vs 13.92%). There was no difference in visual analogue scale score, the incidence of respiratory depression, and bradycardia between groups. Of the three types of pain that prompted patients to request analgesia, the incidence of visceral pain was highest (59.9%, P < 0.01). CONCLUSION: Oxycodone was more potent than morphine for analgesia after laparoscopic endometriosis resection, and oxycodone has fewer side effects than morphine. Name of the registry: Chinese Clinical Trial Registry Trial registration number: ChiCTR1900021870 URL of trial registry record: http://www.chictr.org.cn/edit.aspx?pid=35799&htm=4 Date of registration: 2019/3/13 0:00:00.

Irreversible electroporation ablation against subcutaneously implanted VX2 tumors in rabbits: findings of shearwave ultrasound elastography.

PURPOSE: This study aimed to evaluate stiffness changes of rabbit subcutaneous VX2 tumors before and after irreversible electroporation (IRE) ablationby shearwave ultrasound elastography (SWE). METHODS: IRE was performed on 20 subcutaneously implanted VX2 tumors in rabbits (R-SIVX2). Tumor stiffness was measured by SWE at different time points (before IRE,120minutes after IRE,7 days after IRE and 14 days after IRE). RESULTS: Before IRE, the mean stiffness (Emean) of tumors was (10.45 ± 1.07) KPa. 120 minutes after I RE, the Emean of tumors obviously rose to (70.53 ± 9.87) KPa. 7 days after IRE, the Emean of tumors decreased to (40.22 ± 9.01) KPa. 14 days after IRE, the Emean of tumors was (15.17 ± 1.00) KPa. A clear boundary was observed between the ablation area and the normal tissues in the pathological results. CONCLUSIONS: The stiffness of the VX2 tumors experienced a first rise process and tend to be normal in the procedure of IRE. SWE could provide tissue stiffness information of different IRE ablation period as a non-invasive method.

miRNA-182/Deptor/mTOR axis regulates autophagy to reduce intestinal ischaemia/reperfusion injury.

It had been reported miR-182 was down-regulated after intestinal ischaemia/reperfusion (I/R) damage. However, its role and potential mechanisms are still unknown. This study was aimed to elucidate the function of miR-182 in intestinal I/R injury and the underlying mechanisms. The model of intestinal injury was constructed in wild-type and Deptor knockout (KO) mice. Haematoxylin-eosin staining, Chiu's score and diamine oxidase were utilized to detect intestinal damage. RT-qPCR assay was used to detected miR-182 expression. Electronic microscopy was used to detect autophagosome. Western blot was applied to detect the expression of Deptor, S6/pS6, LC3-II/LC3-I and p62. Dual-luciferase reporter assay was used to verify the relationship between miR-182 and Deptor. The results showed miR-182 was down-regulated following intestinal I/R. Up-regulation of miR-182 reduced intestinal damage, autophagy, Deptor expression and enhanced mTOR activity following intestinal I/R. Moreover, suppression of autophagy reduced intestinal damage and inhibition of mTOR by rapamycin aggravated intestinal damage following intestinal I/R. Besides, damage of intestine was reduced and mTOR activity was enhanced in Deptor KO mice. In addition, Deptor was the target gene of miR-182 and was indispensable for the protection of miR-182 on intestine under I/R condition. Together, our research implicated up-regulation of miR-182 inhibited autophagy to alleviate intestinal I/R injury via mTOR by targeting Deptor.

Helical distributed feedback fiber Bragg gratings and rocking filters in a 3D printed preform-drawn fiber.

Using induced UV attenuation across a twisted fiber asymmetric core drawn from a 3D printed preform, linear fiber Bragg gratings (FBGs) are produced on one side of the core. By removing the twist, a helical grating with a period matching the twist rate is produced. Balancing the rate with the polarization beat length in a form birefringent fiber allows the production of a combined rocking filter and FBG device with tunable properties. Direct observation of the fiber grating dispersion within the rocking filter rejection band is possible.

Thermal-induced luminescence enhancement of BAC-P in bismuth-doped phosphogermanosilicate fibers.

The thermal quenching effect has been systematically investigated in bismuth (Bi)-doped phosphogermanosilicate fiber with varying thermal conditions. For the first time, to the best of our knowledge, the activation of phosphor-related Bi active center (BAC-P) is achieved by thermal quenching at 400°C with a heating time of 10 min, evidenced by the enhanced luminescence of BAC-P (${\sim}{1.3}$∼1.3 times) at 1300 nm. The experimental results reveal that a relatively low heating temperature with prolonged heating time stimulates the growth of BAC-P, whereas higher operating temperatures ($ {\ge} 500^\circ $≥500∘C) result in the irreversible destruction of BAC-P. The underlying mechanism for the thermally stimulated BAC-P process is also analyzed and discussed.

Thermal bleaching of BACs in bismuth/erbium co-doped fiber fabricated through 3D silica lithography.

Bismuth/erbium co-doped optical fiber fabricated through 3D silica lithography is thermally treated with various conditions. Then the thermal treatment effect on bismuth active centers (BACs) in this fiber is investigated. The thermal bleaching of the BAC associated with Al and the BAC associated with Si is observed after thermal treatment at high temperatures (300°C-800°C). It is found that the absorption and luminescence of BACs dramatically decrease after the thermal treatment, even totally bleaching at 700°C. The results show that the temperature and dwell time have significant effects on the thermal bleaching and activation of BACs. The underlying mechanisms of these thermal-induced effects are further discussed.

Photo-induced bleaching and thermally stimulated recovery of BAC-P in Bi-doped phosphosilicate fibers.

The first results of the study on photobleaching and thermally induced recovery in Bi-doped phosphosilicate fiber have been presented. It was revealed that the rate of bleaching of phosphor-related Bi active center (BAC-P) becomes slower with the decrease of photon energy. The quadratic dependence of the bleaching rate of BAC-P on laser power is obtained under 532 nm laser irradiation. The effect of temperature on the bleaching dynamics of BAC-P is also investigated under 532 nm radiation, suggesting a thermally aggravated bleaching process upon heating at certain temperatures (≥300∘C). Furthermore, the thermal recovery of bleached Bi-doped silica-based fiber (BDF) is investigated and a 13% increase of luminescence is achieved upon thermal quenching for 5 min at 400ºC. The underlying mechanism of photobleaching and thermo-stimulated recovery process of BAC-P is also discussed.

Impact of Al2O3 doping on Bi active center photobleaching in Bi/Er-codoped fibers.

In this Letter, the impact of Al2O3 doping on the Bi active center (BAC) photobleaching is investigated in Bi/Er-codoped fibers (BEDFs). By measuring the evolution of emission attributed to the BAC associated with silica (BAC-Si) at ∼1400nm, the linear relationship between the ratio of unbleached/bleached part (γUB/γB) and 830 nm irradiation intensity (P830) was revealed in the log-log plot. The experimental results demonstrate that Al2O3 doping or its induced defects could be one key factor exaggerating the BAC photobleaching in BEDFs.

Ultra-wideband and flat-gain optical properties of the PbS quantum dots-doped silica fiber.

We investigate the microstructural characteristics and optical properties of PbS quantum dots-doped silica fiber (PQDF), prepared by atomic layer deposition (ALD) doping technique. The fiber exhibits ultra-wideband luminescence and flat-gain with 3 dB bandwidth of 300 nm. The on-off gain and net gain can reach to 7.1-15.0 dB and 6.0-9.2 dB at 1050-1350 nm, respectively. The results of high-resolution transmission electron microscopy (HRTEM) further reveal the effects of PbS QDs doping in PQDF. The broadband luminescence spectrum originating from three active centers (1086, 1179, and 1304 nm), can be attributed to the dimension effect of PbS QDs (3.7, 4.0, and 4.3 nm, respectively). Moreover, the calculation results indicate that the multi-sized PbS QDs concentrated at 3.65-4.45 nm make the 3 dB gain bandwidth increase, which is six times wider than that of traditional erbium-doped fiber (EDF). Therefore, this type of PQDF is a promising gain medium for optical amplifiers and broadband light sources.

Effect of thermal treatment parameters on the spectral characteristics of BAC-Al in bismuth/erbium-codoped aluminosilicate fibers.

For the first time, to the best of our knowledge, the effect of thermal quenching on the spectral properties of bismuth-related active centers (BAC)-Al is investigated systematically with varying quenching conditions. It is found that the peak luminescence of BAC-Al at 1140 nm is maximally enhanced by 1.6 times with a heating dwell time of 2 min at 500°C and subsequent quenching, suggesting that a short dwell time with a high heating temperature (500°C) favors the activation or growth of BAC-Al, whereas the prolonged heating time with a slow cooling rate results in the deactivation of BACs and the aggregation of background loss. The underlying mechanism of activation and destruction of BAC-Al is also analyzed and discussed. The experimental results demonstrate a promising strategy for enhancing the spectral performance of BAC-Al in the range of 1.1-1.35 µm.

Effect of pump wavelength and temperature on the spectral performance of BAC-Al in bismuth-doped aluminosilicate fibers.

The near-infrared luminescence of Bi-doped aluminosilicate fiber within pump wavelengths between 710 and 990 nm and under varying pump powers and operation temperatures has been investigated systematically. It is revealed that there exist two emission bands peaking around 1120 and at 1300 nm, which are believed to be associated with two different aluminum-related bismuth active centers (BAC-Al1 and BAC-Al2); the BAC-Al2 is found to be more efficiently excited at a lower temperature within the spectral range of 790-850 nm. This is the first time, to the best of our knowledge, that two sub-bands of BAC-Al are identified. The thermal annealing effect on the luminescence of BACs is also studied under 830 nm pumping. In contrast to the quenching of BAC-Si, the luminescence intensity of BAC-Al1 is enhanced by 1.5 times after 500°C heating and subsequent cooling. The results demonstrate an effective strategy for tuning the emission scheme in the range of 1100-1400 nm by adjusting the excitation wavelength and operation temperature.

Silica optical fiber drawn from 3D printed preforms.

Silica optical fiber was drawn from a three-dimensional printed preform. Both single mode and multimode fibers are reported. The results demonstrate additive manufacturing of glass optical fibers and its potential to disrupt traditional optical fiber fabrication. It opens up fiber designs for novel applications hitherto not possible.

Thermally aggravated photo-bleaching of BAC-Al in bismuth/erbium co-doped optical fiber.

The thermal effect upon the photo-bleaching of bismuth/erbium co-doped optical fiber (BEDF) containing Al has been investigated. The photo-bleaching effects of aluminum related bismuth active center (BAC-Al) in BEDF are studied from room temperature (RT) up to 350°C under the irradiation of a 980 nm laser. No visible bleaching of the luminescence associated with BAC-Al was observed at RT, but significant bleaching appeared at higher temperatures above 150°C under the same irradiation power. The underlying mechanism of significant thermal aggravation of photo-bleaching is discussed, and its impact needs to be considered in the design and application of optical amplifiers and lasers using Al-doped BEDF.