Light Of Wavelength Research Articles

Efficient red light polymerization facilitated by low energy excitation based on a single-atom substituted naphthalimide

Photoinduced polymerization with low-energy, longer wavelength light has attracted enormous attention in material/biological applications owing to its unique advantages of greener and deep curing compared to conventional harsh UV-triggered polymerization. However, the low-energy polymerization methods often rely on heavy atom-containing sensitizers or suffer from the slow solidification process, which restricts their applicability in several areas. Herein we construct a novel efficient photoinitiating system based on a single-atom substituted pure organic triplet photosensitizer, prepared from a common naphthalimide chromophore through a simple one-pot process, and exemplified its potential to enable the efficient and rapid polymerization (just a few tens of seconds) of acrylate upon low-intensity (0.36 W/cm2) red-light illumination. We show that the single atom replacement (oxygen with sulfur) can redshift the absorption profile of naphthalimide chromophore over 150 nm and also effectively promotes its intersystem crossing efficiency (from 0 to 86.4%). For the first time, the thionaphthalimide (NIS) was introduced in triplet-triplet annihilation upconversion, showing a high upconversion quantum yield of (4.4–12.9%) with a large anti-Stokes shift (0.65–0.80 eV) in various solvents. We successfully employed the upconverted annihilator's singlet to trigger the photoinitiator via Förster resonance energy transfer (FRET) for polymerization. Furthermore, this photoinitiating system is found to be effective enough to be operable under sunlight illumination and useful for the fabrication of high-quality flexible products via photolithography approach. Thus, our results are beneficial for the future design of eco-friendly, low-energy activated chemical conversion systems.

Simulation-based investigation of junction-controlled narrow-band Si photodetector with vertical structure

Junction-controlled narrow-band Schottky photodetectors are very attractive in the optoelectronic systems that operate in a small spectral range, due to its high noise immunity, simple structure, and self-powered work mode. In this work, simulation was carried out to study the working mechanism of the junction-controlled narrow-band photodetector based on a vertical silicon Schottky structure. It is showed that the spectral response of the device is mainly dominated by the quasi-neutral region instead of the depletion region of the Schottky structure. Widening quasi-neutral region can obviously red-shift the peak wavelengths of both quasi-neutral region and depletion region, and suppress the device response to short wavelength light. As the doping concentration of the silicon substrate increases, a similar phenomenon can be observed due to the decrease of the diffusion length. Furthermore, increasing surface recombination velocity also can effectively reduce the quantum efficiency of the device at the wavelength <1060 nm. These results signify that junction-controlled narrow-band photodetectors of long-wavelength light can be realized by a variety of simple and feasible methods, indicating their promising application in future photoelectric systems.

Photodynamic inactivation of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa in municipal wastewater by tetracationic porphyrin and violet-blue light: The impact of wastewater constituents.

There is an increasing need to discover effective methods for treating municipal wastewater and addressing the threat of multidrug-resistant (MDR) strains of bacteria spreading into the environment and drinking water. Photodynamic inactivation (PDI) that combines a photosensitiser and light in the presence of oxygen to generate singlet oxygen and other reactive species, which in turn react with a range of biomolecules, including the oxidation of bacterial genetic material, may be a way to stop the spread of antibiotic-resistant genes. The effect of 5,10,15,20-(pyridinium-3-yl)porphyrin tetrachloride (TMPyP3) without light, and after activation with violet-blue light (VBL) (394 nm; 20 mW/cm2), on MDR strains of Pseudomonas aeruginosa, Klebsiella pneumoniae and K. pneumoniae OXA-48 in tap water and municipal wastewater was investigated. High toxicity (~2 μM) of TMPyP3 was shown in the dark on both strains of K. pneumoniae in tap water, while on P. aeruginosa toxicity in the dark was low (50 μM) and the PDI effect was significant (1.562 μM). However, in wastewater, the toxicity of TMPyP3 without photoactivation was much lower (12.5-100 μM), and the PDI effect was significant for all three bacterial strains, already after 10 min of irradiation with VBL (1.562-6.25 μM). In the same concentrations, or even lower, an anti-adhesion effect was shown, suggesting the possibility of application in biofilm control. By studying the kinetics of photoinactivation, it was found that with 1,562 μM of TMPyP3 it is possible to achieve the complete destruction of all three bacteria after 60 min of irradiation with VBL. This study confirmed the importance of studying the impact of water constituents on the properties and PDI effect of the applied photosensitiser, as well as checking the sensitivity of targeted bacteria to light of a certain wavelength, in conditions as close as possible to those in the intended application, to adjust all parameters and perfect the method.

Key determinants for signaling in the sensory rhodopsin II/transducer complex are different between Halobacterium salinarum and Natronomonas pharaonis.

The cell membrane of Halobacterium salinarum contains a retinal-binding photoreceptor, sensory rhodopsin II (HsSRII), coupled with its cognate transducer (HsHtrII), allowing repellent phototaxis behavior for shorter wavelength light. Previous studies on SRII from Natronomonas pharaonis (NpSRII) pointed out the importance of the hydrogen bonding interaction between Thr204NpSRII and Tyr174NpSRII in signal transfer from SRII to HtrII. Here, we investigated the effect on phototactic function by replacing residues in HsSRII corresponding to Thr204NpSRII and Tyr174NpSRII . Whereas replacement of either residue altered the photocycle kinetics, introduction of any mutations at Ser201HsSRII and Tyr171HsSRII did not eliminate negative phototaxis function. These observations imply the possibility of the presence of an unidentified molecular mechanism for photophobic signal transduction differing from NpSRII-NpHtrII.

Multi-channel Deep-UV absorbance measurement setup for multi-capillary electrophoresis with two fiber arrays facing each other

We have developed a simple, compact, and robust eight-channel ultraviolet (UV) absorption detection setup featuring two eight-fiber arrays (an irradiation fiber array and a detection fiber array) whose ends face each other across eight capillaries. UV light of a 220-nm wavelength from a single deuterium lamp is stably and evenly split into eight lights by using a thick homogenizing fiber connected to a fiber bundle with eight thin fibers, which make up the irradiation fiber array. Each capillary is directly irradiated with each UV light emitted from the irradiation fiber array and then each of the UV lights transmitted through the capillaries is collected by each fiber of the detection fiber array without using any other optical devices (e.g., a lens) and is detected by each of the eight photodetectors. This setup achieves simultaneous UV absorption measurement for all eight capillaries with the detection limit of 54 μAU, linear dynamic range of four logs or more, and negligible crosstalk of 0.01% or less. We also implemented an eight-capillary electrophoresis system and simultaneously analyzed eight immunoglobulin G samples, separated by capillary electrophoresis sodium dodecyl sulfate.

Novel green emanating Sr6Al4Y2O15:Er3+ nanophosphor for thermal sensing, data security and personal identification

A novel Er3+ activated Sr6Al4Y2O15 (SAYO:Er) (1–5 mol %) green emitting nanophosphors (NPs) were fabricated. Prepared samples were confirmed for their nanoregime using the advanced characterization techniques. Photoluminescence (PL) emission spectra showed the strongest peak identified at 564 nm with 4S3/2→4I15/2, which is responsible for the intense green colour. A new fluorescence-based platform has been set up to visualize latent fingerprints (LFPs) and latent lip prints (LLPs). With the exposure to ultraviolet light of wavelength of 375 nm, the level -III ridge features which are generally difficult to observe on various surfaces, LFPs can be observed for longer period due to the dual nature of binding specificity and excellent fluorescence properties. Also the LFPs were resulted in higher contrast, high sensitivity and no background interference. For the first time, the latest versions of YOLOv8x program is used for to study the Level-I and Level-II features are readily visible in the enlarged and minute FP. Thrombosis is considered as a major threat to the society as it leads to death and disability. Despite a number of risk factors, oxidative stress may appear to be the primary marker of thrombosis. Therefore, SAYO:Er is analyzed for its ameliorating effect on oxidative stress and thrombosis. Interestingly, SAYO:Er showed antioxidant property by scavenging the DPPH. In addition, SAYO:Er inhibited platelet aggregation induced by ADP. Overall, the findings made it often evident that SAYO:Er NPs provide a novel approach to advanced technology inmedical and forensic applications.

Predicting ischemic stroke risk from atrial fibrillation based on multi-spectral fundus images using deep learning.

Ischemic stroke (IS) is one of the most common serious secondary diseases of atrial fibrillation (AF) within 1 year after its occurrence, both of which have manifestations of ischemia and hypoxia of the small vessels in the early phase of the condition. The fundus is a collection of capillaries, while the retina responds differently to light of different wavelengths. Predicting the risk of IS occurring secondary to AF, based on subtle differences in fundus images of different wavelengths, is yet to be explored. This study was conducted to predict the risk of IS occurring secondary to AF based on multi-spectrum fundus images using deep learning. A total of 150 AF participants without suffering from IS within 1 year after discharge and 100 IS participants with persistent arrhythmia symptoms or a history of AF diagnosis in the last year (defined as patients who would develop IS within 1 year after AF, based on fundus pathological manifestations generally prior to symptoms of the brain) were recruited. Fundus images at 548, 605, and 810 nm wavelengths were collected. Three classical deep neural network (DNN) models (Inception V3, ResNet50, SE50) were trained. Sociodemographic and selected routine clinical data were obtained. The accuracy of all DNNs with the single-spectral or multi-spectral combination images at the three wavelengths as input reached above 78%. The IS detection performance of DNNs with 605 nm spectral images as input was relatively more stable than with the other wavelengths. The multi-spectral combination models acquired a higher area under the curve (AUC) scores than the single-spectral models. The probability of IS secondary to AF could be predicted based on multi-spectrum fundus images using deep learning, and combinations of multi-spectrum images improved the performance of DNNs. Acquiring different spectral fundus images is advantageous for the early prevention of cardiovascular and cerebrovascular diseases. The method in this study is a beneficial preliminary and initiative exploration for diseases that are difficult to predict the onset time such as IS.

The impact of the duration of wave treatment on the development of yeast populations

Introduction: The scientific literature does not contain research on the influence of monochromatic light treatment on the development of bottom-fermenting beer yeast populations.Purpose: An analysis of the literature data allowed us to suppose the possibility of activating the development of the beer yeast Saccharomyces cerevisiae population through preliminary treatment with light of visible spectrum wavelengths, providing technological and economic efficiency of such an impact method on a production scale.Materials and Methods: The object of research was the process of cultivating a population of bottom-fermenting beer yeast Saflager S-189 (Fermentis). The subject was the influence of preliminary treatment of the seed yeast with monochromatic light with a wavelength of 980 nm on this process. Its effectiveness was assessed by the weight loss of the cultivation medium, the increase in the total cell titre, the proportion of unviable and "fed" cells. A KFK-2 photoelectrocolorimeter was used as a source of monochromatic light with wavelengths of the visible range. Seeding of mediums and sample preparation for analysis were performed in a BAVnp-01-"Laminar-S."-1.2 antibacterial air medium box. The yeast's fermenting activity was assessed by the weight loss of the nutrient medium; the total cell titre was established by counting in a Goryaev's chamber; the percentage of unviable cells was determined using methylene blue dye; the percentage of "fed" yeast cells was established by staining glycogen with iodine solution.Results: Preliminary treatment of the seed yeast with monochromatic light (980 nm) allowed increasing the fermenting activity of bottom-fermenting beer yeast by 10-15% compared to the control, which is consistent with the results of other research groups concerning populations of microorganisms of other genera and species. The values of other determined indicators - the proportion of "fed" and unviable cells, the total yeast cell titre - in the experimental variants were at the level of those in the control samples or slightly inferior to them. Data on the influence of the duration of seed yeast irradiation for 60, 120 or 180 minutes on the listed controlled indicators are presented, and the authors express the opinion about the appropriateness of its conduction for 60 minutes.Conclusion: The principle possibility of activating the development of a population of bottom-fermenting beer yeast by preliminary treatment of seed yeast with light with a wavelength of 980 nm, which can give an economic effect on an industrial scale, is substantiated; the necessity of testing the technological method under study in conditions close to production ones, i.e., for brewing wort with an irradiated suspension of seed yeast, is noted.

Sequentially Controlled Recognition of Different Proteins Using Programmable Protein Imprinted Nanospheres.

Although protein imprinted materials with multiple templates are developed to selectively separate different proteins, it is difficult to achieve the programmed adsorption and separation of different proteins using one material, because the available protein imprinted materials are constructed through irreversible crosslinking and their structures are unprogrammable and non-reconstructive. Herein, a novel nanosphere (MS@PTL-g-PNIPAM) is designed, which not only is temperature and pH responsive but also can dynamically reversibly crosslink/de-crosslink under ultraviolet light of different wavelengths. With the help of the dynamically reversible photo-crosslinking, the nanospheres can be repeatedly programmed into protein imprinted nanospheres toward different target proteins. Moreover, the prepared imprinted nanospheres can easily achieve the controlled rebinding and release of target proteins, benefiting from the introduced temperature- and pH-responsive moieties. As a consequence, this study realizes the specific separation of different target proteins from protein mixture and the real bovine blood sequentially by programming one material. It is resource saving, time saving, recyclable, and it will provide convenience for protein imprinted materials to use in the blood purification, drug delivery, and virus detection.

Detecting colorectal lesions with image-enhanced endoscopy: an updated review from clinical trials.

Colonoscopy plays an important role in reducing the incidence and mortality of colorectal cancer by detecting adenomas and other precancerous lesions. Image-enhanced endoscopy (IEE) increases lesion visibility by enhancing the microstructure, blood vessels, and mucosal surface color, resulting in the detection of colorectal lesions. In recent years, various IEE techniques have been used in clinical practice, each with its unique characteristics. Numerous studies have reported the effectiveness of IEE in the detection of colorectal lesions. IEEs can be divided into two broad categories according to the nature of the image: images constructed using narrowband wavelength light, such as narrowband imaging and blue laser imaging/blue light imaging, or color images based on white light, such as linked color imaging, texture and color enhancement imaging, and i-scan. Conversely, artificial intelligence (AI) systems, such as computer-aided diagnosis systems, have recently been developed to assist endoscopists in detecting colorectal lesions during colonoscopy. To better understand the features of each IEE, this review presents the effectiveness of each type of IEE and their combination with AI for colorectal lesion detection by referencing the latest research data.

Optical properties of UV-C irradiated polyvinylidene chloride films

Polyvinylidene chloride (PVDC) polymer films were exposed to ultra-violet light (UV–C light of wavelength 254 nm) in air for different exposure times varying from 1 h up to 6 h. These films were characterized by using ultraviolet–visible (UV–Vis) and Fourier transform infrared (FTIR) spectroscopic, scanning electron microscopy (SEM), as well as powder X-ray diffraction (XRD) techniques. XRD scans reveal that the degree of crystallinity (Xc) increased from 4.7% up to 28.6% on increasing the UV exposure time from 1 h up to 4 h, and a further increase in the exposure time causes a decrease in its value. Analysis of the SEM images revealed an increase in particle size (chemically modified regions) on increased the UV exposure time of PVDC films from 1 h up to 6 h, and the maximum size of these regions were observed for an exposure time of 4 h. The SEM images showed a damaged PVDC surface, the formation of cotton-like fibrous regions, as well as many cracks due to the photo-degradation of polymeric chains. FTIR scans reveal the formation of hydrogen bonded hydroxyl groups as well as carbonyl structures in the PVDC sample on exposure to UV-C radiation. For the study of modification in band structure of the UV irradiated PVDC films, UV–Visible spectroscopy was used. It was found that the optical band gap decreases from 4.70 eV down to 3.92 eV, as obtained from the plot of √εihν versus hν. The penetration depth (δ) decreased from 0.0074 cm down to 0.0035 cm at 4.88eV, the energy corresponding to incident UV-C radiation. The calculation of percentage decrease in the value of δ with respect to wavelength and with variation in UV-C exposure time reveals that UV-C irradiated PVDC films are good radiation shields against both UV-A and UV-B electromagnetic radiation. The study of refractive index with respect to wavelength reveals that UV irradiation of PVDC films is an effective method to modify the refractive index of PVDC, thereby making the material more suitable for use in different optical applications. The optical dielectric constant was studied systematically, which indicated that the energy storage properties of the PVDC films can be tuned and tailored by UV-C radiation. Details are discussed.

Laser therapy in osteoarthritis (literature review)

The authors present a review of the studies of the effect of pulsed laser light in osteoarthritis depending on its wavelength. Laser radiation with wavelength 600 nm stimulates regeneration of bone tissues; laser light wavelength over 800 nm reduces weakness and atrophy of skeletal muscles with a simultaneous increase of extensor strength and joint mobility. Combination of pulsed laser light of various wavelengths has a marked analgesic effect in anti-inflammatory processes at the postoperative period after endoprosthetic surgery.

Gamma irradiation of Ge-doped and radiation-hard silica fibers at cryogenic temperatures: Mitigating the radiation-induced attenuation with 1550 and 970 nm photobleaching

We investigated the effects of gamma irradiation on radiation-induced attenuation (RIA) in photosensitive (Ge-doped) and radiation-hard (F-doped) fibers at cryogenic temperatures (77 K) under different photobleaching conditions. We show that increasing the probe power (1550 nm) and injecting lower wavelength light (970 nm) both resulted in a significant reduction in RIA in both fiber types, where radiation-hard fibers were intrinsically more resistant to the RIA. Deconvolution of RIA growth curves revealed that the RIA was composed of transient and long-term growth components that were correlated with distinct radiation-induced defects specific to each fiber composition. The 1550 nm light more effectively suppressed the transient RIA, while 970 nm more effectively suppressed the long-term RIA. Ultimately, we show that cryogenic RIA may be effectively managed in fiber optic sensing systems using radiation-hard fibers and dual-wavelength photobleaching strategies.

Exposure to long wavelength light that improves aged mitochondrial function shifts acute cytokine expression in serum and the retina.

Aged mitochondrial function can be improved with long wavelength light exposure. This reduces cellular markers of inflammation and can improve system function from fly through to human. We have previously shown that with age there are increases in cytokine expression in mouse serum. Here, we ask what impact 670nm light has on this expression using a 40 cytokine array in blood serum and retina in C57Bl6 mice. 670nm exposure was delivered daily for a week in 12 month old mice. This shifted patterns of cytokine expression in both serum and retina inducing a selective increase. In serum examples of significant increases were found in IL (interleukins) 1α, IL-7, 10, 16, 17 along with TNF-α and CXCL (chemokines) 9 and 10. In retina the increases were again mainly in some IL's and CXCL's. A few cytokines were reduced by light exposure. Changes in serum cytokines implies that long wavelengths impact systemically even to unexposed tissues deep in the body. In the context of wider literature, increased cytokine expression may be protective. However, their upregulation by light merits further analysis as cytokines upregulation can also be negative and there are probably complex patterns of interaction in the dynamics of their expression.

Photodynamic therapy and periodontal disease

Periodontal diseases are global health concern since they affect almost 20-50% of global population and are widespread in both developed and developing countries. Periodontal disease develops as result of persistent infection caused by different periodontopathic bacteria and inflammation of tooth's supporting tissue. Traditional methods of periodontal care involve mechanical removal of biofilm and using antibiotics and antibacterial disinfectants as supplemental measure. However, in locations with restricted access, removal of plaque and decrease in quantity of pathogenic organisms may suffer. Furthermore, increased antibiotic resistance has led to development of newer therapeutic modalities, including photodynamic therapy (PDT). Application of PDT in periodontics, such as pocket debridement, gingivitis, and aggressive periodontitis, continues to develop into fully developed clinical therapeutic modality and is regarded as potential new strategy for eliminating pathogenic bacteria in periodontitis. Photosensitizer activated by light of certain wavelength in presence of O2 is used in PDT, potent laser-initiated photochemical reaction. Because traditional therapy, such as scaling and root planing, is ineffective at entirely eliminating periodontal infections, especially in deep periodontal pockets, antimicrobial PDT may be viewed as alternate therapeutic approach. Additionally, dual selectivity of PDT, which restricts damage to healthy tissues, gives it competitive advantage over alternative therapies. Purpose of this research is to review the available information about PDT and periodontal disease.

Stable and low-threshold photon upconversion in nondegassed water by organic crystals.

Photon upconversion (UC) is a technology that converts lower-energy photons (longer wavelength light) into higher-energy photons (shorter wavelength light), the opposite of fluorescence. Thus, UC is expected to open a vast domain of photonic applications that are not otherwise possible. Recently, UC by triplet-triplet annihilation (TTA) between organic molecules has been studied because of its applicability to low-intensity light, although the majority of such studies have focused on liquid samples in the form of organic solvent solutions. To broaden the range of applications, solid-state UC materials have been an active area of research. We recently developed air-stable, high-performance molecular UC crystals that utilize a stable solid-solution phase of bicomponent organic crystals. This article begins with a brief overview of previous challenges in developing and improving solid-state TTA-UC materials. Then, we briefly review and explain the concept as well as advantages of our molecular solid-solution UC crystals. We applied these organic crystals for the first time to a water environment. We observed blue UC emission upon photoexcitation at 542nm (green-yellow light) and then measured the excitation intensity dependence as well as the temporal stability of the UC emission in air-saturated water. In nondegassed water, these organic crystals were stable, functioned with a low excitation threshold intensity of a few milliwatts per square centimeter, and exhibited high photo-irradiation durability at least over 40h; indicating that the developed organic crystals are also viable for aqueous conditions. Therefore, the organic crystals presented in this report are expected to extend the domain of UC-based photonic applications in practical water systems including in vivo diagnostic, clinical, and therapeutic applications.

Wearable Photoelectric Fingertip Force Sensing System Based on Blood Volume Changes without Sensory Interference.

Monitoring the force of fingertip manipulation without disturbing the natural sense of touch is crucial for digitizing the skills of experienced craftsmen. However, conventional force sensors need to be put between the skin and the objects, which affects the natural sense of the skin. Here, we proposed a fingertip force sensing method based on changes of blood volume and designed a wearable photoelectric fingertip force sensing system (PFFS) for digitalization of traditional Chinese medicine (TCM) pulse diagnosis. The PFFS does not interfere with the fingertips' tactile sense while detecting fingertip force. This PFFS detects the change of blood volume in fingertip by photoelectric plethysmography and can obtain the change of output current under different fingertip forces. We also studied the effect of various factors on PFFS output signals, including emission lights of different wavelengths, ambient temperature, and the user's heartbeat artifact. We further established the relationship between the change of blood volume and fingertip force by combining experimental and theoretical methods. Moreover, we demonstrated the feasibility of the PFFS to detect fingertip forces under commonly used conditions in TCM pulse diagnosis without sensory interference. This PFFS also shows promise for perceiving the viscosity of objects and recognizing gestures in human-computer interaction. This work paves the way for the digitalization of fingertip forces during TCM pulse diagnosis and other fingertip forces under natural conditions.

Novel salicylic acid derivatives connecting to five-membered cycle through an acyl hydrazone bond as multi-stimuli responsive fluorescent smart materials with photoswitching properties

In order to exploit novel multi-stimuli responsive fluorescent materials, a series of novel fluorescent molecules of salicylic acid derivatives were designed and synthesized via introducing pyrazole or cyclopentane to the salicylic acid scaffold through a special Schiff base–acylhydrazone, and the molecular structures of representative compounds A2 and A4 were verified via single crystal X–ray diffraction. All title molecules could exhibit obvious solvatofluorochromism from cyan to indigo in several solutions with different polarity. The fluorescence titration data exhibited compound A2 and complex A2-Cu2+ with prime detection limits to Cu2+ (0.24 μM) and S2- ions (2.83 μM). The sensitive recognition of A2 to trifluoroacetic (TFA) and A2-TFA to triethylamine (TEA) were also confirmed via fluorescent titration experiments in various solutions, respectively. What’s more, the 1H NMR and UV/Vis absorption spectra further explained the mechanism between molecules and ions or molecules and TFA/TEA. Besides, the photoswitching properties of the compounds A2 and A3 could be demonstrated via the irradiation of special wavelength light or heating accompanied with changes in quantum yields. In addition, these phenomena of multiple responses were explained via Density Functional Theory (DFT) based on the Gaussian calculations. Thus, this work provided a preliminary basis for the research of multi-stimuli responsive fluorescent molecules with photoswitching properties.

Sustainable polylactide materials with the function of blocking a specific wavelength of light based on aloe-emodin

Polylactide, a biodegradable polymer, can alleviate white pollution, but the use of polylactide in food packaging is limited by high transmittance to light with a specific wavelength, UV (185–400 nm) and short-wavelength visible (400–500 nm) light. Herein, the polylactide end-capped with renewable light absorber aloe-emodin (PLA-En), is blended with commercial polylactide (PLA) to fabricate the polylactide film with the function of blocking light with a specific wavelength, PLA/PLA-En film. Only 40 % of light around 287 and 430 nm transmits through PLA/PLA-En film incorporating 3 mass% of PLA-En, while the film still maintains good mechanical properties and high transparency more than 90 % at 660 nm because of the good compatibility with PLA. The PLA/PLA-En film exhibits stable light-blocking properties under light irradiation and anti-solvent migration under the immersion of fat simulant. Almost no PLA-En migrated out of the film with the molecular weight of PLA-En only 2.89 × 104 g/mol. Compared with PLA film and commercial PE plastic wrap, the designed PLA/PLA-En film exhibits a better preservative effect on riboflavin and milk for inhibiting the production of 1O2. This study offers a green strategy for developing UV and short-wavelength light protective food package film based on renewable resource.

High-power two-color Kerr frequency comb generation on the gallium phosphide-on-insulator platform at SWIR and MIR spectra

Optical frequency combs (OFCs) covering multiple spectral windows are of great interest as broadband coherent light sources. Pushing into high powers for traditional single OFCs as well as nonlinear frequency translated OFCs led to the narrowing of their bandwidths. Here, we present a hybrid integrated solution on the gallium phosphide-on-insulator (GaP-OI) platform to generate high-power two-color Kerr frequency combs at both the short-wave infrared (SWIR) and the mid-infrared (MIR) spectra. The design consists of a GaP-OI resonator with a partially etched gap for frequency comb generation at the two colors and a modal phase-matched strip waveguide for a second-harmonic generation (SHG). The resonator has a 3.25 µm wide anomalous dispersion window, which is enabled by mode hybridization and higher-order modes waveguide dispersion. The pump light at 1550 nm wavelength is frequency doubled from the 3100 nm wavelength light source, with a normalized SHG conversion efficiency of 793%W−1cm−2. We also propose the ring-bus coupler design to efficiently deliver optical power into the resonator while suppressing the leakage out of the resonator. The simulated two-color combs show a bandwidth of 87 nm above the −30dBm power level at the SWIR spectrum and a bandwidth of 749 nm above the same power level at the MIR spectrum. Our proposed two-color OFC generation scheme levitates the ceiling in terms of high power and broad bandwidth simultaneously on a single platform, paving the way toward monolithic solutions to integrated broadband coherent sources.