Investigation of a twisting-fused side-pump coupler based on tellurite fiber.

Fiber side-pump couplers can enhance the output power of fiber laser due to their dependable and efficient operation and impressive power handling capability. We developed a tellurite fiber side-pump coupler by twisting and fusing a tapered pump fiber onto a target fiber. The effect of twisting parameters on coupling efficiency was comprehensively investigated through theoretical simulations and experiments. Experimental results exhibited an impressive coupling efficiency of 76.5% and a root mean square stability of 0.086% and 0.091% before and after one month, respectively, driven by an incident pump power of up to 4.2 W.

High-efficiency and broadband tunable Raman fiber laser in a chalcogenide fiber based on the Fresnel reflection.

A high-efficiency and broadband tunable chalcogenide fiber Raman laser with the Fabry-Perot (F-P) cavity formed by the Fresnel reflection was established. A maximum average power slope efficiency of around 43% and a maximum output peak power of about 2.9 W at 2148 nm were demonstrated by using a 2 µm nanosecond pump source. The laser shows a broadened pulse width of 674 ns and a broadband tunability of the central wavelength from 2100 to 2186 nm. The Raman Fabry-Perot cavity constituted by the Fresnel reflection from chalcogenide fiber endfaces can operate at any wavelength without the aid of any additional optical feedback element. This will facilitate the realization of fiber lasers with excellent performance and compact system, especially in the mid-infrared region.

Detection of copper ions in an aqueous solution by a dual-peak long period fiber grating functionalized with a polypyrrole-chitosan composite.

A dual-peak long period fiber grating (DP-LPFG) sensor functionalized by polypyrrole-chitosan composite was proposed for sensitive detection of Cu2+ ions in aqueous solution. The nitrogen atom on the polypyrrole ring and the amino group on the chitosan chain in the complex matrix can chelate the Cu2+ ions. Thus, the refractive index of the overlay changed and further modulated the transmission spectrum of DP-LPFG. After special design, the double peaks can move in opposite directions with the increase of Cu2+ ion concentration, thereby greatly improving detection sensitivity. The linear sensitivity of the fabricated sensor was measured to be 9.12 and 2.14 nm/ppm (0.61 and 0.14 nm/µM) for concentrations of 0.1-0.5 (1.5 µM-7.5 µM) and 0.5-2 ppm (7.5 µM-30 µM), respectively. In addition, the Langmuir isothermal model was used to evaluate the overall response of the sensor to Cu2+ ions quantitatively, and the detection limit was determined to be 0.05 ppb (0.75 nM). This ingenious sensor offers a new solution for sensitive detection of heavy metal ions in environmental water.

High Q-factor, ultrasensitivity slot microring resonator sensor based on chalcogenide glasses: erratum.

We correct the error in [Opt. Express30, 3866 (2022)10.1364/OE.450092], Fig. 6(c). The unit of the vertical axis in the figure should be arbitrary units, not dB. All the conclusions are unchanged after the correction.

Fabrication of a tellurite-fiber-based side-pump coupler based on the tapered-fused method.

In this study, (1 + 1) × 1 side-pump couplers made of tellurite fibers were fabricated and investigated. The whole optical design of the coupler was established on the basis of ray tracing models and validated by experimental results. By optimizing the preparation conditions and structural parameters, the tested component achieved a coupling efficiency of 67.52% and an insertion loss of 0.52 dB. To the best of our knowledge, this is the first time a tellurite-fiber-based side-pump coupler was developed. The fused coupler presented will simplify many mid-infrared fiber lasers or amplifier architectures.

Design and fabrication of large-mode-area multicore chalcogenide fiber with low bending loss.

Multicore fiber (MCF) has a larger mode-area (LMA) compared to traditional single-core fiber, making it easy to get a mode area of more than 3000 µm2 with an optimized MCF structure. Here, a fine-structured 19-core fiber based on chalcogenide glass was fabricated using a combined method involving extrusion, drilling, and rod-in-tube for the first time. The fiber has a minimum transmission loss of 1.8 dB/m at 6.7 µm. When the bending radius exceeds 6 cm, a low bending loss of about 0.6 dB appears, and the experimental data are in good agreement with the simulation results. In addition, the supermode characteristics of the 19-core fiber are analyzed from both perspectives of simulation and experiment, and these results are perfectly in good agreement. We believe it opens a new way to develop high-power and bend-resisting fiber with such kind of multicore structure.

Single-mode suspended large-core chalcohalide fiber with a low zero-dispersion wavelength for supercontinuum generation.

Chalcogenide glass possesses outstanding advantages, such as supercontinuum generation, but its nonlinear applications were limited by large zero-dispersion wavelength (ZDW). Traditional suspended-core fibers can shift the ZDW to near IR with a tiny core size of less than 5 µm but a large evanescent wave loss exists in these fibers. In this paper, we prepared a novel suspended-core fiber (SCF) based on chalcohalide glasses for the first time via the extrusion method, in which the ZDW of the fundamental mode in the fiber with a core size of larger than 30 µm was successfully shifted to 2.6 µm. We also calculated confinement loss (CL) of propagation modes and fundamental mode energy ratio in the fiber. We found that the minimum CL ratio of the high order modes (LP11) to the CL of the fundamental mode is 124, indicating that the single-mode operation condition is satisfied when the wavelength is more than 4.6 µm. The lowest transmission loss is 1.2 dB/m at 6.5 µm. An ultra-broad supercontinuum spectrum, covering from 1.6 to 12 µm was generated in this suspended-core fiber pumped by a 5 µm femtosecond laser. Such a wide SC in the chalcogenide SCF is due to the large core size. All these results demonstrate the potential to use the large core SCF in the application of a mid-IR laser.

High Q-factor, ultrasensitivity slot microring resonator sensor based on chalcogenide glasses.

In this article, the chalcogenide slot waveguide is theoretically studied, and the highest power confinement factors of the slot region and the cladding region are obtained to be 36.3% and 56.7%, respectively. A high-sensitivity chalcogenide slot microring resonator sensor is designed and fabricated by electron-beam lithography and dry etching. The structure increases the sensitivity of the sensor compared with the conventional evanescent field waveguide sensor. The cavity has achieved a quality factor of 1 × 104 by fitting the resonant peaks with the Lorentzian profile, one of the highest quality factors reported for chalcogenide slot microring resonators. The sensor sensitivity is measured to be 471 nm/RIU, which leads to an intrinsic limit of detection of 3.3 × 10--4 RIU.

Rapid and sensitive detection of ammonia in water by a long period fiber grating sensor coated with sol-gel silica.

A sensitive ammonia sensor based on long-period fiber grating (LPFG) is designed and manufactured for the detection of ammonia concentration in water. Femtosecond laser direct writing technology is used to write LPFGs on standard single-mode silica fiber. A thin layer doped with basic dyes is coated on the optical fiber for sensing by using the sol-gel method. The thicknesses of sol-gel layers, which play a key role in the sensitivity of the LPFG sensor, were carefully studied. Experimental results show that LPFG with a functional layer of ∼340 nm has the best sensing performance, and the detection limit is 0.08 ppm. The response time of the sensor is less than one minute, and the sensor has good repeatability with a short recovery time. Compared with other organic molecules and ions in water, the proposed LPFG sensor has not only good reusability, but also selectivity for the detection of ammonia.

Se-H-free As2Se3 fiber and its spectral applications in the mid-infrared.

The complete removal of the impurities like Se-H in Se-based chalcogenide glasses has been challenging in the development of highly transparent chalcogenide glass fiber. In this paper, several purification methods, including dynamic distillation, static distillation, and combined distillation method, were adopted with an aim of purifying arsenic selenide glass with ultra-low content of the impurities. The experimental results demonstrated that the Se-H can be completely eliminated in the arsenic selenide glass host and fiber without the introduction of any chloride. We further explored the applications of such low loss and Se-H-free chalcogenide glass fiber in the mid-infrared. It was found that, using such a Se-H free fiber, a flattened supercontinuum spectrum above the -30 dB level from 1.2 to 13 µm was generated from the Se-H free fiber with a 5.5 µm laser pumping. The sensitivity was found to be improved 5.1 times for CO2 gas in the 3 to 6 µm wavelength range.

NIST Interlaboratory Study on Glycosylation Analysis of Monoclonal Antibodies: Comparison of Results from Diverse Analytical Methods.

Glycosylation is a topic of intense current interest in the development of biopharmaceuticals because it is related to drug safety and efficacy. This work describes results of an interlaboratory study on the glycosylation of the Primary Sample (PS) of NISTmAb, a monoclonal antibody reference material. Seventy-six laboratories from industry, university, research, government, and hospital sectors in Europe, North America, Asia, and Australia submitted a total of 103 reports on glycan distributions. The principal objective of this study was to report and compare results for the full range of analytical methods presently used in the glycosylation analysis of mAbs. Therefore, participation was unrestricted, with laboratories choosing their own measurement techniques. Protein glycosylation was determined in various ways, including at the level of intact mAb, protein fragments, glycopeptides, or released glycans, using a wide variety of methods for derivatization, separation, identification, and quantification. Consequently, the diversity of results was enormous, with the number of glycan compositions identified by each laboratory ranging from 4 to 48. In total, one hundred sixteen glycan compositions were reported, of which 57 compositions could be assigned consensus abundance values. These consensus medians provide community-derived values for NISTmAb PS. Agreement with the consensus medians did not depend on the specific method or laboratory type. The study provides a view of the current state-of-the-art for biologic glycosylation measurement and suggests a clear need for harmonization of glycosylation analysis methods.

Spectral fitting method for obtaining the refractive index and thickness of chalcogenide films.

Spectral fitting method (SFM) was proposed to obtain the refractive index (RI) and thickness of chalcogenide films based on transmission spectra. It extended the Swanepoel method to the films on the order of hundreds of nanometers in thickness. The RI and thickness of the films can be obtained quickly and accurately by using the SFM based on the transmission spectrum with only one peak and valley. The method's reliability theoretically was evaluated by simulation analysis. The results showed that the accuracy of the RI and thickness was better than 0.2% by using the SFM regardless of thin or thick film. Finally, the RI and thickness of the new ultralow loss reversible phase-change material Sb2Se3 films were obtained experimentally by the SFM. This work should provide a useful guideline for obtaining the RI and thickness of the transparent optical films.

Effects of Shendibushen on the Expression of CD146 and its Metabolic Pathways.

Context: Evidence from multiple studies has revealed that it's meaningful to evaluate the clinical significance of CD146 because it's related to an early diagnosis of chronic renal failure as well as to the severity of illness and the patient's prognosis. Objective: The current study intended to evaluate the therapeutic effects of Shendibushen on the clinical parameters of blood and urine and on fibrosis in the kidney in a rat model, using simulated renal tissue fibrosis that was surgically induced with unilateral ureteral obstruction (UUO). Also, our research team intended to analyze the metabolic pathway activated by Shendibushen both in rat and human kidneys through use of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database and the GeneNetwork. The aim is to discover if a connection existed between CD146 and key genes in these pathways. Design: The research team conducted an animal study in Wistar rats. Intervention: The rats were divided into 5 groups of 14 animals each: (1) blank control group, (2) sham control group, (3) model group, (4) Niaoduqing group, and (5) Shendibushen group. Three groups had UUO surgically induced-the model, Niaoduqing, and Shendibushen groups. The sham control group received sham surgery, and the blank control group received no surgery. The Shendibushen and Niaoduqing groups received the relevant capsules once a day at a fixed time, for a total of 28 days. Outcome Measures: The levels of serum creatinine, blood urea nitrogen, microalbuminuria, serum soluble CD146, and urinary soluble CD146 were measured on the 14th and 28th days after modeling the rats. The degree of renal interstitial fibrosis was examined by hematoxylin and eosin (HE) staining and Masson trichrome staining. The changes at transcriptome level were obtained by target tissue sequencing. The KEGG database was used to analyze the potential pathway activated by the Shendibushen treatment. The GeneNetwork analysis was used to validate the correlation and identify the connections between CD146 and the key genes of the potential pathways. Results: Shendibushen capsules decreased the degree of renal interstitial fibrosis in the UUO rat model and reduced the serum creatinine, blood urea nitrogen, microalbumin, serum sCD146, and urinary sCD146 significantly compared to the model group (P < .05). Upon analysis of the metabolic pathways activated by Shendibushen, the study further verified, through use of the KEGG database, that CD146 activated the nuclear factor kappa B1 (NF-κB1) and transforming growth factor beta 1 (TGF-ß1)/ SMAD family member 2 (SMAD2) pathways. Conclusions: CD146 could become an early indicator in clinical monitoring. CD146 has a function related to the NF-κB1and TGF-ß1/ SMAD2 pathways under Shendibushen treatment.

Femtosecond laser direct writing of diffraction grating and its refractive index change in chalcogenide As2Se3 film.

Chalcogenide glasses possess novel optical property in infrared range, which make them ideal candidates for photonic devices by laser direct writing. Precisely control of the refractive index manipulation in the material is the key to achieve high quality optical devices. In this work, diffraction gratings in chalcogenide As2Se3 thin films were fabricated with femtosecond laser direct writing and its refractive index change was carefully studied. Grating diffraction efficiency was measured from visible to near-infrared light by using multiple single-wavelength lasers and a supercontinuum laser. Clear diffraction patterns and high diffraction efficiency indicated the good optical quality of the prepared gratings. Results show that the grating with period of 5 µm inscribed under pulse energy of 30 nJ demonstrated a 1st-order diffraction efficiency of 30% at 808 nm testing wavelength, due to the changes of refractive index and absorption. The relationship of the change of refractive index and absorption coefficient of film under different laser irradiation intensity is carefully studied. The maximum refractive index change was estimated to be 0.087 at 808 nm.

In situ and ex-situ physical scenario of the femtosecond laser-induced periodic surface structures.

Laser-induced periodic surface structures (LIPSS) are a universal phenomenon that can allow tailoring nanoelectronics and nanophotonics devices. However, there is an issue about the formation mechanism of LIPSS, and the current research mainly focuses on the formation process of the individual structures, such as the low spatial frequency LIPSS (LSFL), sub-wavelength structures, and laser-induced periodic annular surface structures (LIPASS). A whole process formation picture of the series of these periodic structures is still missing. In this study, a pump-probing setup is applied to ensure the real-time and in situ monitoring of surface modification under different pulse numbers. LSFL firstly appears on the surface after two laser shots, and then, laser-induced orthogonal periodic structures (LIOPS) become the dominant morphology after five laser shots, which result from the local field enhancement of the surface ripples. As the laser shots increase, the LSFL split leads to the formation of nanopillars, and the formation of the nanopillars under the surface LSFL (after ten laser shots) is due to the transition between the LSFL and HSFL with an orientation parallel to the laser polarization. A dip surrounded by annular periodic fringes after 50 laser shots is observed, which is due to the interference of the incident laser field and the reflected laser field on the crater surface. Finally, a direct writing technique for fabrication of nano-gratings is also reported.

Ultrabroadband and coherent mid-infrared supercontinuum generation in Te-based chalcogenide tapered fiber with all-normal dispersion.

We demonstrated an ultrabroadband supercontinuum (SC) generation with high coherence property in all-normal-dispersion (ANDi) Te-based chalcogenide tapered fiber. The fibers made of Ge20As20Se15Te45 core and Ge20As20Se20Te40 cladding glasses were fabricated via isolated stacked extrusion. The waist diameter and length can be accurately controlled by a homemade tapering platform. When the core diameter of the waist was ≤14 µm, the fiber showed an ANDi characteristic in the wavelength range of 1.7-14 µm. A coherent SC generation covered 1.7-12.7 µm was generated in a 7-cm-long tapered fiber, pumped at 5.5 µm. To the best of our knowledge, this is the first SC experimental demonstration in Te-based step-index tapered fiber and the broadest SC generation in chalcogenide tapered fiber when pumped in the normal dispersion regime so far.

Mid-infrared flattened supercontinuum generation in all-normal dispersion tellurium chalcogenide fiber.

We have prepared a well-structured tellurium chalcogenide (ChG) fiber with a specialized double cladding structure by an improved extrusion method, and experimentally demonstrated an ultra-flat mid-infrared (MIR) supercontinuum (SC) generation in such a fiber. The step-index fiber had an optical loss of <1 dB/m in a range from 7.4 to 9.7 µm with a minimum loss of 0.69 dB/m at 7.87 µm. Simulation showed that an all-normal dispersion profile can be realized in this double cladding tellurium fiber. An ultra-flat MIR SC spectrum (~3.2-12.1µm at -10 dB, ~2-14 µm at -30 dB) was generated from a 22-cm long fiber pumped with a femtosecond laser at 5 µm (~150 fs, 1 kHz). Then the degree of coherence was calculated out based on a simulation, showing that a high coherent MIR SC (from 2.9 to 13.1 µm) can be generated in this double-cladding tellurium fiber.

1.2-15.2 µm supercontinuum generation in a low-loss chalcohalide fiber pumped at a deep anomalous-dispersion region.

A novel low-loss selenium-based chalcohalide fiber, with a low zero-dispersion wavelength, was prepared by an innovative preparation process. The composition optimized fiber has a wide transmission range of up to 11.5 µm, a lowest fundamental mode zero-dispersion wavelength of 4.03 µm, and a minimum optical loss of 1.12 dB/m at 6.4 µm, which provides a possibility to replace As2S3 and As2Se3 in a cascade of ZrF4-BaF2-LaF3-AlF3-NaF(ZBLAN)-As2S3-As2Se3 fiber in the practical all-fiberized supercontinuum (SC) source. Meanwhile, the broadest SC spectrum, ∼1.2 to 15.2 µm, was achieved by pumping a 12-cm-long fiber with a femtosecond laser at a deep anomalous-dispersion region. Furthermore, simulations are adopted to interpret the results as well as to demonstrate spectral evolution along the fiber. To the best of our knowledge, this is the broadest SC spectrum reported in any selenium-based chalcogenide fiber.

Multi-omics profiling of CHO parental hosts reveals cell line-specific variations in bioprocessing traits.

Chinese hamster ovary (CHO) cells are the most prevalent mammalian cell factories for producing recombinant therapeutic proteins due to their ability to synthesize human-like post-translational modifications and ease of maintenance in suspension cultures. Currently, a wide variety of CHO host cell lines has been developed; substantial differences exist in their phenotypes even when transfected with the same target vector. However, relatively less is known about the influence of their inherited genetic heterogeneity on phenotypic traits and production potential from the bioprocessing point of view. Herein, we present a global transcriptome and proteome profiling of three commonly used parental cell lines (CHO-K1, CHO-DXB11, and CHO-DG44) in suspension cultures and further report their growth-related characteristics, and N- and O-glycosylation patterns of host cell proteins (HCPs). The comparative multi-omics and subsequent genome-scale metabolic network model-based enrichment analyses indicated that some physiological variations of CHO cells grown in the same media are possibly originated from the genetic deficits, particularly in the cell-cycle progression. Moreover, the dihydrofolate reductase deficient DG44 and DXB11 possess relatively less active metabolism when compared to K1 cells. The protein processing abilities and the N- and O-glycosylation profiles also differ significantly across the host cell lines, suggesting the need to select host cells in a rational manner for the cell line development on the basis of recombinant protein being produced.

All-optical switching in long-period fiber grating with highly nonlinear chalcogenide fibers.

All-optical switching in long-period fiber grating (LPFG) with Ge-As-Se chalcogenide fibers was proposed. The switching performances at different resonant wavelengths and cladding modes were systematically investigated using coupled-mode theory. By utilizing the ultra-high nonlinearity of chalcogenide glass, the switching power threshold of the proposed LPFG switching at 1.55 µm was 105 MW/cm2 with power coupling for the low-order LP09 cladding mode, which was approximately 200 times lower than that of silica LPFG. Furthermore, the temperature stability of the proposed LPFG switching was examined. The optical switching instability due to the laser thermal effect can be well suppressed by optimizing the cladding radius and grating period. Considering the balance between temperature sensitivity and switching power threshold, an all-optical switch with temperature sensitivity of 51 pm/°C was finally realized by selecting the LP051 mode with a cladding radius of 39 µm.