This study involves a simulation-based optimization of a wavelength division multiplexing (WDM) in a passive optical network system, and an RZ modulator, with incorporating a vertical cavity surface ...emitting laser (VCSEL) and an edge-emitting (CW) laser alternately. Two scenarios have been proposed. First, 8 VCSEL/CW lasers, having distinctive frequency, are assigned for each user in the WDM PON. In the second scenario, only one optical source (193.1 THz) is employed to share among the eight users of the PON. The first scenario supports 5 Gbps up to 150 km fiber length, and comparably, the VCSEL-based system provides a better Q-factor performance comparable with the CW laser-based system. The second scenario confirmed the transmission of 20 Gbps up to 150 km by the VCSEL-based system, while the CW laser system allowed 20 Gbps up to only 100 km, while demonstrating a lower Q-factor.
The inverse problem of amplitude reconstruction on an inclined plane based on the values of amplitude or its module as recorded on semi-infinite plane orthogonal to the beam propagation direction is ...considered within the framework of 2D parabolic equation. It is demonstrated that this inverse problem, in case when the complex image plane amplitude is known, can be reduced to a singular Cauchy-type integral equation. The existence of its solutions requires that certain conditions be met but if a solution exists it is necessary unique. The obtained integral equation is then approximated piece-wisely and the resulting linear algebraic system is solved numerically while applying necessary regularization procedures to enhance the stability of its solutions. Finally, an iterative method of phase retrieval is developed and a set of numerical experiments is performed.
The generation and reusing of a self-pulsated optical RZ carrier is demonstrated to achieve bi-directional OC-768 transmission with downstream return-to-zero binary phase-shift keying (RZ-BPSK) and ...reused upstream return-to-zero ON-OFF keying (RZ-OOK) data formats at 40-Gbit/s. The self-started optical RZ carrier is generated by linking a single-mode laser with a nonlinearly biased Mach-Zehnder modulator based self-feedback loop, which is externally modulated to transmit the downstream RZ-BPSK and reused to transmit the upstream RZ-OOK. By lengthening the true-time delay in the self-feedback loop with a 900-m long SMF, the self-started 40-GHz photonic-microwave clock with an ultralow SSB phase noise of -160 dBc/Hz at an offset frequency of 100 kHz could suppress its relative timing jitter to 2 fs for obtaining a Q-factor as high as 5 × 10 16 . Both the photon-microwave clock and optical RZ carrier can be triggered to achieve bi-directional downstream RZ-BPSK and upstream reused RZ-OOK transmissions with receiving power sensitivities of -15.7 and -12.3 dBm, respectively, at a requested BER of 10 -9 . The bi-directional downstream RZ-BPSK data reveals a comparable BER performance with the uni-directional case by a power penalty of only 0.5 dB, whereas the power penalty between uni- and bi-directional upstream RZ-OOK data is up to 3 dB.
Morse potential, a basic interaction potential used in the study of the non-harmonic oscillations between atoms and molecules, can be used for studying diatomic molecules. The full description of ...Morse interaction can be done using three parameters, and one important parameter of Morse potential is the bond distance of the equilibrium state of the potential. This parameter describes the equilibrium situation of the interaction itself. In this communication, we aim to derive a novel formula for the previous equilibrium distance. We derive the formula depending on the basic principle of the integral equation theory of the distribution functions. Depending on the derived formula, we find that the bond distance of the equilibrium state is a function of the temperature of the system via a nonlinear relationship. Also, we find that the bond distance of the equilibrium state is a function of the other two parameters of the Morse potential. Based on the derived formula, we found that the bond distance of the equilibrium state increases slowly with the absolute temperature of the system. Also, we calculate this bond distance for two diatomic molecules: the first one is the hydrogen chloride molecule, and the other is the hydrogen fluoride molecule. The bond distance of the equilibrium state, which are calculated in this work, are reliable and comparable to the experimental results of this distance.
A free-running Fe:ZnSe laser is demonstrated under the pump of a single-shot 2.94 μm Er:YAG laser along the cavity axis at liquid nitrogen temperature of 77 K. At the incident pump energy of 1.47 J, ...a maximum single pulse energy of 253.7 mJ is obtained with a minimum pulse duration of 92.4 μs, corresponding to a slope efficiency of 16.2%. The central wavelength and the full width at half maximum (FWHM) are 3944.7 and 68.4 nm, respectively.
This study reveals the dark, bright, combined dark–bright, singular, combined singular optical solitons and singular periodic solutions to the conformable space–time fractional complex ...Ginzburg–Landau equation. We reach such solutions via the powerful extended sinh-Gordon equation expansion method (ShGEEM). Constraint conditions that guarantee the existence of valid solitary wave solutions are given. Under suitable choice of the parameter values, interesting three-dimensional graphs of some of the obtained solutions are plotted.
A BiF3 powder sample was prepared from the purchased Bi2O3 powder via the precipitation route. The photocatalytic performance of the prepared BiF3 powder was compared with the Bi2O3 powder and ...recognized as superior. The prepared BiF3 powder sample was added in a plaster of Paris (POP) matrix in the proportion of 0%, 1%, 5%, and 10% by wt% to form POP–BiF3(0%), POP–BiF3(1%), POP–BiF3(5%), and POP–BiF3(10%) composite pellets, respectively, and activated the photocatalytic property under the UV–light irradiation,in the POP. In this work, Resazurin (Rz) ink was utilized as an indicator to examine the photocatalytic activity and self-cleaning performance of POP–BiF3(0%), POP–BiF3(1%), POP–BiF3(5%), and POP–BiF3(10%) composite pellets. In addition to the digital photographic method, the UV–visible absorption technique was adopted to quantify the rate of the de-colorization of the Rz ink, which is a direct measure of comparative photocatalytic performance of samples.
Lotus-like ZnO morphology with reduced graphene oxide was synthesized by sol-gel method using ammonia solution as a reducing agent. It was observed that ammonia solution, reduced graphene oxide (rGO) ...and working temperature influenced the assembly of inverted and non-inverted lotus like ZnO morphologies with variable sizes in the micrometer range. This type of morphology was successfully developed in the nanosized range and appeared on the surfaces of rGO sheets as well as between their interlayer's. These arrangements influence in enhancing optical and photocatalytic properties. The prepared composites in the above manner also showed better photocatalytic activities for the removal of phenol compound under sunlight irradiation and resulted in maximum degradation efficiency of around 86% in 20 min.
•Efficient, high-power, passively Q-switched Yb:YCOB/WS2 laser is demonstrated.•Output power in 4-W level at 0.61 MHz is produced with a slope efficiency of 47%.•Shortest pulse duration of 66 ns is ...achieved.
We report an efficient high-power Yb:YCa4O(BO3)3 laser that was passively Q-switched by a few-layer WS2 saturable absorber. A maximum average output power of 4.05 W was produced at a pulse repetition rate of 606 kHz, with an optical-to-optical efficiency of 40.5% and a slope efficiency of 47%. The resulting pulse energy, duration, and peak power were 6.67 μJ, 66 ns, and 101 W, respectively. Our work demonstrates the great potential of few-layer WS2 and other 2D transition metal dichalcogenides as saturable absorbers for developing high-power, high-repetition-rate, nanosecond, pulsed solid-state lasers.
Muskmelons are currently grown in several areas of Vietnam for domestic and international consumer markets. The fruit grows well in greenhouses in soil or soilless substrate such as coconut peat. ...Researchers in Vietnam are investigating the growth of muskmelons in a range of organic by-products. In this study, spent mushroom substrate was recycled for use as an organic substrate and to evaluate the growth, quality, and yield of three muskmelon varieties including RZ F1, PN 128, and TL3 in greenhouses over three months. The substrate was incubated for one month before use and contained 45% spent mushroom substrate, 30% manure, 7.7% rice husks, 1.5% phosphorus, 0.2% commercial Trichoderma (Tribac), 0.1% rice bran, 15% sand, and 0.5% micronutrients and water. Following incubation, the substrate had optimal pH for the growth of muskmelon and the concentration of nutrients and beneficial microorganisms had increased significantly. The growth of RZ F1 and TL3 cultivars was significantly better than PN 128 in terms of growth, fruit quality, and yield. Specifically, RZ F1 and TL3 species took 78 days and 75 days to complete their life cycle produced 1.76 kg and 1.62 kg of fruit, had a pericarp thickness of 4.0 cm, and possessed 14.20o Brix and 14.88o Brix of soluble solid content, respectively. These findings suggest that agricultural by-products, such as spent mushroom substrate, could be a valuable resource for the culture of muskmelons in Vietnam.
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