1550-nm Wavelength Research Articles

Improved inverse design of polarization splitter with advanced Bayesian optimization

As many silicon nanophotonic devices are polarization-dependent, a polarization beam splitter that divides TE and TM modes is an essential component for photonic integrated circuits. Various structures have been proposed for polarization splitters, but it is still challenging to simultaneously achieve low insertion loss, high extinction ratio, compact size and simplicity of fabrication. In this paper, we combine new machine learning methods with the principle of multimode interference to propose a novel design for a polarization beam splitter. Our design has low insertion loss (-0.17dB/-0.42dB) and high extinction ratio (-23.1dB/-23.4dB) at the central wavelength of 1550nm for TE/TM modes, with compact size of 2×19μm2 and fabrication constraints strictly satisfied. Furthermore, our design is a standard 220nm-thick single-layer device for the silicon-on-insulator platform, without any auxiliary structures, making it easy for fabrication. Since our design cannot be optimized by the most commonly used methods, we adopt several specialized techniques to Bayesian optimization for inverse design. In this paper, we also share these skills which are simple but effective, possible to solve much more complicated design problems than others.

Exploring the photosensitizing potential of Nanoliposome Loaded Improved Toluidine Blue O (NLITBO) Against Streptococcus mutans: An in-vitro feasibility study.

Streptococcus mutans is a major contributor to dental caries due to its ability to produce acid and survive in biofilms. Microbial resistance towards common antimicrobial agents like chlorhexidine and triclosan has shifted the research towards antimicrobial Photodynamic therapy (PDT). In this context, Toluidine Blue O (TBO) is being explored for its photosensitizing properties against Streptococcus mutans. There is a huge variation in the effective concentration of TBO among the current studies owing to the differences in source of and delivery system TBO as well as the time, power and energy densities of light. The primary objectives of this study are to encapsulate improved Toluidine Blue O (ITBO) in nanoliposomes (NLITBO), characterize it, and evaluate its antibacterial photosensitizing potential against Streptococcus mutans suspensions in vitro. ITBO was synthesised as per Indian patent (number -543908). NLITBO was prepared using the thin-film hydration method. Dynamic light scattering experiment determined the vesicle size, polydispersity index (PDI), and zeta potential. Surface features were characterized by Scanning and Transmission Electron microscopy. ITBO release from NLITBO was assessed using the extrapolation method. The antibacterial activity of the NLITBO was determined by evaluating the zone of inhibition (ZOI) in the Streptococcus mutans culture and comparing with 2% chlorhexidine gluconate. The minimum inhibitory concentration (MIC) of NLITBO as a photosensitizer with red light (wavelength 650nm, power density 0.1 W/cm2, energy density 9-9.1 J/ cm2, 90seconds time) was evaluated against Streptococcus mutans cells by colorimetric method in 96 well plate. Percentage drug loading, loading efficiency, yield percentage, vesicle size, PDI, Zeta potential of NLTBO was reported as 9.3±0.4%, 84.4±7.6%, 73.5%, 123.52 nm, 0.57, -39.54mV respectively. Clusters of uni-lamellar nanovesicles with smooth non-perforated surfaces were observed in SEM and TEM. The size of the vesicle was within 100 nm. At 24 hours, a cumulative 79.81% of ITBO was released from NLITBO. Mean ZOI and MIC of NLITBO (1 μg /ml) were found to be 0.7±0.2 mm, 0.6μg/ml respectively. We have synthesized and encapsulated improved Toluidine Blue O (ITBO) in nanoliposomes (NLITBO) and thoroughly characterized the formulation. The antibacterial efficacy of NLITBO without light was demonstrated by ZOI which is similar to 2% chlorhexidine gluconate. MIC of NLITBO as a photosensitiser along with the optimal light parameter was also proposed in this study. These findings suggested that NLITBO could serve as an effective alternative to conventional antibacterial treatments in managing Streptococcus mutans rich biofilms. It can have potential pharmaceutical application in oral health care.

Dual-mode 1 × 2 optical switch with simultaneous modulation based on inverse design devices

Abstract Mode division multiplexing (MDM) technology, based on the parallelism inherent in mode dimensions, provides an advancement in enhancing on-chip optical communication channel capacity. In MDM communication systems, the routing and switching of optical signals are of essential importance. However, conventional multimode optical switches typically follow the demultiplexing-processing-multiplexing technological route, leading to an unavoidable increase in device size. In scenarios where multiple modes need to be routed synchronously, the implementation of simultaneous modulation optical switches offers a more efficient and feasible solution. Here, we propose two 1×2 dual-mode optical switches with simultaneous modulation on a silicon-on-insulator (SOI) platform in the 1525-1565 nm wavelength range, utilizing two optical phase modulation techniques: mode transformation and waveguide widening. Simultaneously, we employ inverse design methodologies based on the adjoint variable method (AVM) and level-set method to create the compact single-connected devices, which are compatible with CMOS fabrication processes. The experimental results show that the insertion losses for both TE0 and TE1 modes are less than 1.6 dB (2.5 dB), with the worst modal crosstalk at most -13.5 dB (-12.7 dB) for the switch based on mode transformation (waveguide widening) strategy at the wavelength of 1550nm. The extinction ratio (ER) of the two proposed optical switches exceeds 25 dB at the same wavelength. Furthermore, the switches exhibit a 10%-90% rise time of 15.2 μs and a 90%-10% fall time of 19.5 μs at 1550 nm, indicating the switching speed can be up to kilohertz (kHz). Our proposed 1×2 optical switches hold potential as a fundamental unit for optical signal switching in high-integration multimode optical communication systems.

Table-top source for x-ray absorption spectroscopy with photon energies up to 350 eV.

We present a table-top setup for x-ray absorption spectroscopy (XAS) based on high harmonic generation (HHG) in noble gases. Using sub-millijoule pump pulses at a central wavelength of 1550nm, broadband HHG in the range of 70-350eV was demonstrated. The HHG coherence lengths of several millimeters were achieved by reaching the nonadiabatic regime of harmonic generation. Near edge x-ray absorption fine structure spectroscopy experiments on the boron K edge of a boron foil and a hexagonal boron nitride (hBN) 2D material demonstrate the capabilities of the setup. Femtosecond pulse duration makes pump-probe XAS experiments with corresponding time resolution possible.

A EVALUASI KINERJA CWDM 8 CHANNEL DENGAN VARIASI PANJANG GELOMBANG: FOKUS POWER LINK BUDGET, SNR DAN BER

The need for internet connection continues to grow and is the main priority of the Indonesian population. The use of fiber optic as a transmission system aims to increase data transfer speed and is resistant to interference. The use of CWDM technology can overcome high traffic volumes by dividing the wavelength. PT. Surya Citra Media has a network that connects the SCTV tower office with the IVM office in Daan Mogot. This study examines the performance of the CWDM fiber optic network link SCTV Tower - IVM Daan Mogot. The CWDM used has a capacity of 8 channels with a wavelength of 1310nm to 1450nm with a channel spacing of 20nm. This study was conducted to evaluate the 8-channel CWDM fiber optic network through performance measurements. The performance of the fiber optic network is focused on the parameters of the power link budget, SNR and BER. The results showed a power link budget of -9.407 dB and an SNR value with the smallest value of 37.0864 and the largest of 37.6150 dB. While the BER value ranges from 10-10 to 10-11. So that the network can be declared feasible based on the evaluation results.

Antibacterial synergistic effect of sea cucumber extract and kelulut honey combination

Natural products remain one of the major sources of new drug molecules today. The combination of sea cucumber extract with stingless bee honey holds great potential for health supplement. However, the specific results of the combination have yet to be determined. In this study, the antibacterial activity of kelulut honey and Phyllophorus spiculata sea cucumber extract samples individually and in combination were assessed with disk-diffusion assays and broth dilution method. Most of the samples exhibit small or absence of inhibitory activity using disk-diffusion assay method. Only kelulut honey sample with 100% concentration has a positive antagonism effect against Escherichia coli and Staphylococcus epidermidis. For the broth dilution method, Gram-positive bacteria were found to be more susceptible as compared to Gram-negative bacteria species, with lower minimum inhibitory concentration (MIC) value of kelulut honey, sea cucumber or combination sample. The growth of gram-positive S. epidermidis is inhibited by sea cucumber extract at MIC value of 0.031 mg/mL, kelulut honey at MIC value of 0.063 mg/ mL and combination sample at MIC value of 0.063 mg/mL, all of which are of lower MIC value as compared to E. coli inhibition. The absorbance at optical density (OD) 600nm wavelength was also measured to monitor the growth of bacteria in solution. From the results, broth dilution proves to be a more effective method to assess the antibacterial activity in the combination samples. Two combinations showed the best antibacterial synergy (OD600 value of 0.000) against both Gram-positive and Gram-negative bacteria, which were (1) ½ sea cucumber: ½ kelulut honey combination and (2) ¾ sea cucumber: ¼ kelulut honey combination. This preliminary evidence on their antibacterial synergistic activities is promising and shows possible commercialization potential.

Coarse frequency offset estimation and compensation based on short-time spectrum analysis in FSO communication system

Due to the high-speed movement of low-orbit satellites, the Doppler frequency offset in 1550-nm wavelength satellite-to-ground coherent laser communication is as high as ±4.5 GHz, which greatly increases the difficulty of carrier frequency acquisition. Low complexity, short capture time, and stable coarse frequency offset estimation and compensation algorithms are technical bottlenecks that must be addressed. In this work, a coarse frequency offset estimation and compensation algorithm based on short-time spectrum analysis is proposed. In the proof-of-principle system, the feasibility of the coarse frequency offset capture is verified based on a 2.5-GBaud data rate PM-QPSK modulation FPGA-based coherent receiver. The results show that the frequency offsets capture range is extended to ±4.5 GHz, covering the Doppler frequency offset range. Moreover, the standard deviation of the residual frequency offset after coarse frequency offset compensation is less than 140 MHz, which is smaller than the accurate frequency offset compensation range of 312.5 MHz.

P-089 Sperm motility and sperm DNA fragmentation evaluation after irradiation with a 633nm He-Ne laser in donor samples. An in vitro pilot study

Abstract Study question Does a 633nm laser irradiation on sperm samples improve sperm motility safely? Summary answer 633 nm wavelength He-Ne laser irradiation for 5 and 10 minutes increases slow progressive and non-progressive sperm motility without modification of the DNA fragmentation. What is known already Sperm motility has been hypothesized to increase after light radiation excitation of cytochrome c- oxidase, which boost adenosin triphosphate (ATP) synthesis, in a range of wavelength between 600-1000 nm. One of the main problems of this stimulation is the generation of Reactive Oxigen Species (ROS) that may affect sperm DNA integrity. Previous studies have approached to this field showing different results. Study design, size, duration In vitro pilot study of 15 sperm samples donated for research between June 2022 and October 2023 which were irradiated with a 633nm wavelength He-Ne laser. Each sample was split in 4 aliquots of 10 microliters. To study sperm motility analysis, two videos of each were recorded, before and after irradiation, anonymized and evaluated later by a single embryologist. Sperm motility was annotated according to WHO 2021 criteria. Participants/materials, setting, methods After laser calibration and alignment, sperm samples were irradiated at 37 ºC in a Makler chamber with a continuous emission laser with a gaussian-like beam thirty cm. away for 5,10,15 and 20 minutes. Two videos were obtained for each aliquot, before and after irradiation. Radiant exposure was calculated using the equation y = 1030 x-1,626. Sperm Chromatine Dispersion (SCD) test was employed in 50 µl aliquots to study DNA fragmentation. Shapiro-Wilk and paired t-student tests were employed. Main results and the role of chance We observed a significant increase in slowly progressive motility; -0.075 [-0.12 – 0.024] (p = 0.007); and non-progressive motility; -0.023 [-0.041 – -0.006] (p = 0.011); after irradiating samples between 5 and 10 minutes with a total radiant exposure, 0.4830 and 0.9661 (mW/mm2 * min). Also, for total progressive motility; -0.075 [-0.13 – -0.01] (p = 0.024), and total motility; -0.069 [-0.126 – -0.012) (p = 0.021). No differences were found in sperm DNA fragmentation index after irradiating for 10 minutes; -1.347 [-4.073 - 1.380] (p = 0.32) nor for 20 minutes of irradiation -1.587 [-4.400 - 1.227] (p = 0.25). According to our results, irradiation of sperm samples between 5 and 10 minutes with a 633nm wavelength laser, increases type b and type c motility spermatozoa without affecting sperm DNA fragmentation. Longer irradiations, 15 and 20 minutes, do not show an improvement in sperm motility, neither in sperm DNA fragmentation in our set of data. Limitations, reasons for caution This in vitro pilot study has not been proved in samples to clinical use and our findings need a confirmation with clinical samples in animals to ensure the safety in the conceptions and offspring. We included samples with normal sperm values. Results should be confirmed in samples with motility defects. Wider implications of the findings Our findings are the first step in a new way to modify the sperm motility in vitro throughout laser exposition, which may benefit patients with severe asthenozoospermia without the use of chemical motility inductors. We hope to confirm the safe clinical use in animals before translation to humans. Trial registration number 1909-VGO-082-JA

Design and simulation implementation of bismuth-doped fiber laser

Rare-earth doped fibers are an important means of expanding the wavelength band of optical fibers. Currently, researchers aim to broaden the working wavelength band of optical fibers by doping with different rare-earth elements, thereby increasing the amount of information that can be transmitted. In this paper, a bismuth-doped fiber laser operating around 1300nm was designed. A basic physical model for implementing a bismuth-doped fiber laser was proposed based on the energy levels and transition processes of bismuth, rate, and power propagation equations. It was possible to determine the link between pump power and laser power at a wavelength of 1300 nm by modeling tests using the physical model. Additionally, the relationship between pump light and laser power in bismuth-doped fiber at different positions and propagation directions was analyzed. Suggestions for the future large-scale application of bismuth-doped fiber lasers around the 1300nm wavelength band were provided.

Reverse design of multifunctional cascade devices based on the adjoint method

In this paper, a 1×4 ultra-compact wavelength division multiplexing cascaded device(DMC) with an arbitrary splitting ratio based on adjoint topology optimization reverse design is proposed, which is approximately two orders of magnitude smaller than that of conventional waveguide devices. It can simultaneously perform wavelength demultiplexing, mode conversion, and arbitrary ratio power splitting. The DMC separates 1310 nm and 1550 nm wavelengths, converts the input light from fundamental transverse mode (TE0) to first-order transverse mode (TE1) and second-order transverse modes (TE2), and performs arbitrarily proportional power splitting of the converted higher-order light source.

Establishment of a steroid binding assay for goldfish membrane progesterone receptor (mPR) by coupling with graphene quantum dots (GQDs).

A homogeneous assay was developed to evaluate ligands that target the membrane progesterone receptor alpha (mPRα) of goldfish. This was achieved by employing graphene quantum dots (GQDs), a type of semiconductor nanoparticle conjugated to the goldfish mPRα. When progesterone-BSA-fluorescein isothiocyanate (P4-BSA-FITC) was combined with the other agents, fluorescence was observed through Förster resonance energy transfer (FRET). However, this fluorescence was quenched by binding between the ligand and receptor. This established method demonstrated the ligand selectivity of the mPRα protein. Then, the methylotrophic yeast Pichia pastoris was used to express the goldfish mPRα (GmPRα) protein. The recombinant purified GmPRα protein was coupled with graphene quantum dots (GQDs) to generate GQD-conjugated goldfish mPRα (GQD-GmPRα). Fluorescence at a wavelength of 520nm was observed through FRET upon the combination of P4-BSA-FITC and subsequent activation by ultraviolet (UV) light. Adding free P4 to the reaction mixture resulted in a decrease in fluorescence intensity at a wavelength of 520nm. The fluorescence was reduced by the administration of GmPRα ligands but not by steroids that do not interact with GmPRα. The findings indicated that the interaction between the ligand and receptor led to the formation of a complex involving GQD-GmPRα and P4-BSA-FITC. The interaction between the compounds and GQD-GmPRα was additionally validated by a binding experiment that employed the radiolabeled natural ligand [3H]-17α,20β-dihydroxy-4-pregnen-3-one. We established a ligand-binding assay for the fish membrane progesterone receptor that is applicable for screening compounds.

Demonstration of a compact double-reflection transmissive beam scanner operating at 1550 nm wavelength.

A compact forward-directed transmissive beam scanner operating at a wavelength of 1550nm was constructed and characterized. The scanner consists of two wire-grid polarizers (WGPs) surrounding a 45° Faraday rotator, causing incident light to reflect once from each WGP before transmitting through the second polarizer. Scanning is achieved by tilting one of the WGPs. Measured efficiency remained above 73% over a 90° forward scan range (-45∘ to +45∘) for vertically polarized incident light. Additionally, we measured the efficiency versus beam deflection for four different incident linear polarization configurations, three of which maintained >70% efficiency for deflection angles up to -60∘.

Design nano cluster high Q-factor perfect plasmonic absorber for bacteria detection in the optical range

Plasmonic nanostructures enable strong light absorption at the nanometer scale, making them highly attractive for a variety of applications including sensing, imaging, and spectroscopy. In this work, we propose and simulate a dual-band plasmonic absorber based on a Pentamer and split ring resonator (SRR) hybrid structure. The absorber operates at terahertz frequencies of 209 and 229 THz, corresponding to free-space wavelengths of 1310 nm and 1430 nm. At the lower frequency band, the absorber provides perfect absorption up to 100 %, while at the higher band, the absorption is 95 %. The high absorption selectivity at the two target bands is enabled by the hybrid heptamer-SRR design. The central Pentamer consists of a central nanodisk surrounded by four peripheral nanodisks with precise dimensions and spacing. This Pentamer provides a dual-band response tuned to the desired frequencies. To further enhance the quality factor and absorption, the Pentamer is encircled by an SRR designed to boost the Q-factor. At 229 THz, the SRR pushes the quality factor to around 635, significantly higher than typical plasmonic absorbers. The final optimized design enables strong absorption together with high Q-factor and frequency selectivity. It exhibits sensitivity around 450 nm/RIU and a Figure of Merit of 227 RIU−1. The full-wave simulation is used for designing the absorber in CST Microwave Studio to optimize the dimensions for maximum dual-band absorption for biosensing applications. This absorber can be realistically fabricated for terahertz sensing applications such as detecting bacteria as studied.

Application of COMSOL Multiphysics for Fiber Beam Profiling

Fiber optic beam profiling is essential across scientific and engineering realms, demanding precise characterization of light beams for optimized system performance, accurate alignment, and efficient resource utilization. This study employs COMSOL Multiphysics to comprehensively analyze single-mode and multimode fiber beam profiles, encompassing diverse parameters such as wavelengths and modal distributions. The investigation of beam profiles is based on 850nm, 1310nm and 1550nm wavelengths; with three different modes (1, 5, and 20). COMSOL Multiphysics enhances beam profiling by providing precise numerical techniques, multiphysics modeling, and flexible parameter analysis. Its user-friendly interface facilitates efficient research, while validation and innovative possibilities underscore its value in photonics advancements. The research addresses the need for advanced profiling techniques, offering a robust methodology that captures intricate modal interactions and boundary conditions. Key findings include distinctive beam waist evolution, mode distribution patterns, and beam shaping behaviors, impacting data transmission, medical procedures, and manufacturing. By integrating computational power, this study advances our understanding of photonics, providing practical insights for future fiber optic technologies and their broader implications.

Superconducting wide strip photon detector with high critical current bank structure

The single-photon detector is an essential technology in photonic quantum information science and technology. Large-scale photonic quantum computers and quantum networks inevitably require numerous high-performance single-photon detectors. Superconducting nanostrip single-photon detectors (SNSPDs) using around 100-nm-wide nanostrips are promising technologies with high detection efficiency, low dark count, and low jitter, but there has been room for evolution in terms of polarization dependence and productivity. Using wide strips with widths of tens of micrometers provides polarization-independent high detection efficiency and high-yield fabrication using high-throughput photolithography with submicron resolution. However, detecting photons with such wide strips has been challenging due to rapidly increasing intrinsic dark counts caused by the uneven distribution of the superconducting current in the strip. Here, we present a novel superconducting wide strip photon detector (SWSPD) with a high critical current bank (HCCB) structure. This new strip structure suppresses the intrinsic dark counts and provides highly efficient photon detection in the wide strips. We have simultaneously achieved a polarization-independent detection efficiency of over 78% for 1550-nm wavelength photons, a low dark count rate (DCR) of ∼80 cps, and a low jitter of 29.8 ps using a 20-µm-wide SWSPD with the HCCB structure. This result paves the way for a new class of photon detectors using ultra-wide superconducting strips. These photon detectors with excellent productivity and polarization-independent high detection performances would boost the advance of large-scale photonic quantum technologies.

On-chip multifunctional polarizer based on phase change material.

Polarizers are used to eliminate the undesired polarization state and maintain the other one. The phase change material Ge2Sb2Se4Te1 (GSST) has been widely studied for providing reconfigurable function in optical systems. In this paper, based on a silicon waveguide embedded with a GSST, which is able to absorb light by taking advantage of the relatively large imaginary part of its refractive index in the crystalline state, a multifunctional polarizer with transverse electric (TE) and transverse magnetic (TM) passages has been designed. The interconversion between the two types of polarizers relies only on the state switching of GSST. The size of the device is 7.5µm∗4.3µm, and the simulation results showed that the extinction ratio of the TE-pass polarizer is 45.37dB and the insertion loss is 1.10dB at the wavelength of 1550nm, while the extinction ratio (ER) of the TM-pass polarizer is 20.09dB and the insertion loss (IL) is 1.35dB. For the TE-pass polarizer, a bandwidth broader than 200nm is achieved with ER>20dB and IL<2.0dB over the wavelength region from 1450 to 1650nm and for the TM-pass polarizer, ER>15dB and IL<1.5dB in the wavelength region from 1525 to 1600nm, with a bandwidth of approximately 75nm.

Research on the Low-loss Low-crosstalk Bending-insensitive Seven-core Fiber

Multicore fiber is regarded as the most efficient way to realize SDM networks. Fabrication of low-loss and low-crosstalk multi-core fiber is the key to achieving high-capacity communication systems. This paper designed and fabricated low transmission loss seven-core single-mode fiber with a standard 125μm cladding diameter based on modified chemical vapor deposition. The preform of MCF is fabricated using drilling method. The seven-core fiber has achieved a low transmission loss of 0.19~0.28dB/km throughout the 1250-1600nm wavelength range. The transmission loss is below 0.19dB/km at 1550nm wavelength. The crosstalk is below -54dB/100km from 1200nm to 1600nm wavelength by utilizing a trench-assisted structure. At 1550nm wavelength, the bending loss (BL) is lower than 0.45dB/m with a bending radius of 5 mm, and the BL is 0.05dB/m with a bending radius of 15 mm. The fabricated multi-core fiber can be used for long-haul transmission and space division multiplexing communication systems.

Low-loss and power-efficient phase shifter based on an optimized multimode spiral silicon waveguide.

Low-loss and energy-efficient phase shifters are an effective tool to reduce the power consumption of large-scale photonic integrated circuits. In this work, a low-loss and power-efficient thermo-optic phase shifter has been demonstrated on the silicon-on-insulator platform. The multimode spiral waveguide is optimized to obtain lower power consumption and low cross talk. The waveguide width is beyond the single-mode region in consideration of low propagation loss. The optimized ultra-low loss 180° Bezier bends are used to further reduce the bending loss. The experimental results show that the excess loss of the phase shifter is only 0.36 dB at 1550-nm wavelength and the power consumption is 4.87 mW/π.

Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry

ObjectivesThe aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content.MethodsResin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation’s tests, while Vicker’s hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey’s test (p < 0.05).ResultsAfter polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78–80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content.ConclusionsA high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites.Clinical significanceThe type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation.Graphical

Reconfigurable TE-pass polarizer based on lithium niobate waveguide assisted by Ge2Sb2Te5 and silicon nitride.

On-chip polarization management components play a critical role in tackling polarization dependence in the lithium-niobate-on-insulator (LNOI) platform. In this work, we proposed a reconfigurable TE-pass polarizer based on optical phase change material (GST) and the LNOI wafer. The key region is formed by a hybrid GST-S i 3 N 4 layer symmetrically deposited atop the centerline of the LNOI waveguide along the propagation direction where the GST is sandwiched in the middle of the S i 3 N 4 layer. Whether the polarizer will take effect depends on the phase states of the GST layer and the graphene and aluminum oxide layers are coated atop the G S T-S i 3 N 4 layer as the microheater to control the conversion of phase states. The proposed device length is 7.5µm with an insertion loss (IL)=0.22dB and extinction ratio (ER)=32.8dB at the wavelength of 1550nm. Moreover, it also has a high ER (>25d B) and a low IL (<0.5d B) in the operating bandwidth of 200nm. Such a high-performance TE-pass polarizer paves a new way for applications of photonics integrated circuits.