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The paper investigates methods for shifting the spectral characteristics of silicon photodiodes toward longer wavelengths. It is established that with increasing the reverse bias voltage of the photodiode, the maximum spectral characteristic shifts towards longer wavelengths due to an increase in the collection coefficient of minority charge carriers, which determines the appearance of the spectral characteristic. With an increase in the lifetime of minor charge carriers and the resistivity of the photodiode base material, the maximum of its spectral characteristic also shifts towards longer wavelengths. Increasing the n+-junction depth of the photodiode reduces the effect of background short-wave radiation on the useful signal of the photodiode. Silicon cut-off adsorption light filters have been proposed that eliminate the influence of background radiation with a wavelength of less than 800 nm on the photodiode signal and have a transmittance of about 75% at a wavelength of 1064 nm.

The article presents experimental results of the synthesis and study of thin films of polycrystalline vanadium dioxide (VO2), as well as multilayer optoresonance structures based on them. The role of the influence of thermal annealing on the structural, electrical and optical properties of VO2 films is shown. Based on these films, photonic crystal heterostructures were fabricated, in which excitation of optical resonance modes of the Fabry–Perot type is observed. A study of the optical transmission of such a structure showed that the spectral position of the Fabry–Perot mode can be controlled by varying the thickness of the VO2 gradient optical layer. It is shown that the first-order semiconductor-metal phase transition, which occurs in VO2 films and is accompanied by a change in their electrical conductivity by 3–5 orders of magnitude, leads to a change in the optical parameters of both the films themselves and multilayer optoresonance structures. [ABSTRACT FROM AUTHOR]

In order to develop materials able to guarantee optimal characteristics in terms of environmental compatibility, abundance, and photoactivity, zinc telluride (ZnTe) has become a great candidate for optoelectronic and photovoltaic device applications. In this work, on the basis of electrochemical techniques including cyclic voltammetry and chronoamperometry, it was found that the electrodeposition of zinc telluride (ZnTe) on indium tin oxide substrate (ITO) is a quasi-reversible reaction controlled by the diffusion process. The nucleation and growth mechanism follows the instantaneous three-dimensional process according to Scharifker and Hill model. The crystallographic structure and film morphology were studied by XRD and SEM analyses, respectively. ZnTe films have a cubic crystal structure, and they are characterized by good homogeneity. The optical measurements of the deposited films were performed, and a direct energy gap of 2.39 eV was determined by UV–visible spectroscopy. [ABSTRACT FROM AUTHOR]

Designing a DWDM system for fiber optic transmissions requires optimizing some important parameters to enable the system to be more tolerant to nonlinear impairments. This paper proposes a simulation of a 32-channels system with different bit rates per channel, for different modulation formats (RZ, NRZ, 4-QAM, and DQPSK) then the Gaussian (Gauss) and Hyperbolic Secant (Sech) pulses. The main goal is to investigate the resilience of the designed system to nonlinear effects, taking into account the different modulation formats and bit rates used. Thus, several comparisons were taken into account in the different simulations carried out with the optisystem software. The results reveal that for a bit rate of 40 Gbps per channel, the order of performance is NRZ, Sech, 4-QAM, RZ, and DQPSK; whereas for a bit rate of 100 Gbps per channel, the order becomes NRZ, DQPSK, 4-QAM, Sech, and RZ. For a bit rate of 100 Gbps without nonlinear effects, the 4-QAM format would be more efficient than other modulation formats for the input powers considered (−10 dBm to 10 dBm). While this same 4-QAM format is more vulnerable to nonlinear effects beyond an input power of 5 dBm. At a bit rate of 100 Gbps, the DQPSK format would be more resilient to nonlinear effects for input powers between −10 dBm and 8 dBm for the simulated system. [ABSTRACT FROM AUTHOR]

The integrable substrate for THz modulation directly influences both the quality of films and THz absorption. Currently, the available THz substrate candidate library is still not clear. Here, we have carried out a systematic investigation of commonly used commercial substrates, including Si, quartz SiO2, MgO, Al2O3, GdScO3 and TbScO3 in the range of 0.4–1.6 THz. It is found that low resistance Si, TSO and GSO are certainly not appropriate for THz light modulation due to their relatively higher absorption and dielectric constant, while the rest show better THz transmittance, low refractive index and loss. However, the dielectric constant and refractive index of high resistance Si are generally two times larger than quartz SiO2, Al2O3 and MgO. Compared with Al2O3 and MgO, quartz SiO2 shows at least 50% lower dielectric constant, refractive index and absorption, making it the best candidate. Our research is believed to build the rich substrate candidate library for THz range light modulation. [ABSTRACT FROM AUTHOR]

In this paper, parameters that effectively contribute to glass surface degradation from sandblasting erosion processes are investigated and optimized on the basis of the method of Taguchi. The polystyrene glass used in this work has been eroded taking into account the projected sand mass, the particles' grain size and the velocity as the main influencing parameters by looking at specimens' surface roughness (SR) and optical transmission (OT). Taguchi's Design L9 orthogonal array of experiments has been implemented in order to obtaining the best combination among these parameters. The significant parameters affecting the responses have been determined on the basis of variance analysis. These have revealed that the particles' size and velocity are the most effective parameters on the responses OT and SR of the degraded surface with 92 and 56% contribution, respectively. These optimized influential parameters' combinations have revealed severe eroding processes occurring to the polystyrene glass surface as confirmed by the optical micrographs. [ABSTRACT FROM AUTHOR]

Glycinium oxalate (GO) and Bis(glycinium) oxalate (BGO) crystals are successfully grown using the slow evaporation solution growth technique. Following their growth, the crystals are subjected to a series of acoustic shock pulses. The effects of these shock pulses on the structural, optical, dielectric, and morphological properties of the crystals are comprehensively analyzed using various characterization techniques, including powder X‐ray diffraction (XRD), UV‐Visible spectroscopy, dielectric spectroscopy, and optical microscopy. Structural analysis through XRD reveals shifts in diffraction peak positions, indicating structural deformations. Fourier transform infrared spectroscopy analysis assesses the chemical stability of GO and BGO under shocked conditions. UV‐Visible spectroscopy shows alterations in optical transmission with successive shock pulses, attributed to structural and surface defects. Dielectric properties are investigated over a frequency range from 1 Hz to 1 MHz, revealing variations in dielectric constant and loss tangent, which provide insights into the electrical behavior of the materials under normal and shocked conditions. Optical and scanning electron microscopy examine surface morphology, visualizing defects induced by the shock pulses. This study highlights the significant impact of shock pulses on the structural properties, optical transmission, dielectric properties, and surface morphology of GO and BGO crystals, offering valuable information on their resilience under dynamic conditions and potential applications. [ABSTRACT FROM AUTHOR]

The integrable substrate for THz modulation directly influences both the quality of films and THz absorption. Currently, the available THz substrate candidate library is still not clear. Here, we have carried out a systematic investigation of commonly used commercial substrates, including Si, quartz SiO2, MgO, Al2O3, GdScO3 and TbScO3 in the range of 0.4–1.6[Formula: see text]THz. It is found that low resistance Si, TSO and GSO are certainly not appropriate for THz light modulation due to their relatively higher absorption and dielectric constant, while the rest show better THz transmittance, low refractive index and loss. However, the dielectric constant and refractive index of high resistance Si are generally two times larger than quartz SiO2, Al2O3 and MgO. Compared with Al2O3 and MgO, quartz SiO2 shows at least 50% lower dielectric constant, refractive index and absorption, making it the best candidate. Our research is believed to build the rich substrate candidate library for THz range light modulation.

Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long wavelengths due to the formation of large superficial defects like chipping by creation and propagation of lateral cracks. The coating of the sandblasted samples exhibits some healing of defects induced by sandblasting. The deposition of the SiO2-ZrO2 layer induces a clear increase in the optical transmission values, sometimes exceeding the initial values of the transmission in the pristine state.

This paper describes the recent advances in device designs and optical transmission applications of semiconductor optical amplifiers (SOA). The device advances described are quantum-dot-based SOA and photonic-integrated circuits using SOA. The use of nonlinear properties of SOAs in high-speed optical transmission is discussed. [ABSTRACT FROM AUTHOR]

Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long wavelengths due to the formation of large superficial defects like chipping by creation and propagation of lateral cracks. The coating of the sandblasted samples exhibits some healing of defects induced by sandblasting. The deposition of the SiO2-ZrO2 layer induces a clear increase in the optical transmission values, sometimes exceeding the initial values of the transmission in the pristine state. [ABSTRACT FROM AUTHOR]

Results are presented from optical profilometry and scanning probe microscopy studies of the structures and surface parameters of germanium single crystals exposed to an alternating magnetic field. A change in the relief and surface roughnesses of the crystals after magnetic field processing and a drop in their optical transmittance in the range of 1.8–23 μm are established. [ABSTRACT FROM AUTHOR]

CuGaO2 thin films were deposited using the RF magnetron sputtering technique using Cu2O and Ga2O3 targets. The films were deposited at room temperature onto a quartz slide. The sputtering power of Cu2O remained constant at 50 W, while the sputtering power of Ga2O3 was systematically varied from 150 W to 200 W. The films were subsequently subjected to annealing at temperatures of 850 °C and 900 °C in a nitrogen atmosphere for a duration of 5 h. XRD analysis on films deposited with a Ga2O3 sputtering power of 175 W annealed at 900 °C revealed the development of nearly single-phase delafossite CuGaO2 thin films. SEM images of films annealed at 900 °C showed an increasing trend in grain size with a change in sputtering power level. Optical studies performed on the film revealed a transmission of 84.97% and indicated a band gap of approximately 3.27 eV. The film exhibited a refractive index of 2.5 within the wavelength range of 300 to 450 nm. [ABSTRACT FROM AUTHOR]

CdTe1–xSex (x = 0.75 and 0.95) thin films were deposited on quartz substrate by the method of high-frequency magnetron sputtering. The chemical composition analysis and crystal structure refinement was examined with using X-ray fluorescence spectroscopy and X-ray diffraction data. CdTe1–xSex thin films crystallizes in hexagonal structure [structure type—ZnO, space group P63mc (No. 186)]. Unit cell parameters decrease with increasing Se content in CdTe1–xSex thin films. The value of the optical band gap for CdTe0.25Se0.75 and CdTe0.05Se0.95 was estimating using the Tauc plot and from the maximum position of the first derivative of the transmittance dT/dλ. [ABSTRACT FROM AUTHOR]

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Humankind has entered a new era wherein a main characteristic is the convergence of various technologies providing services and exerting a major impact upon all aspects of human activity, be it social interactions with the natural environment. Fixed networks are about to play a major role in this convergence, since they form, along with mobile networks, the backbone that provides access to a broad gamut of services, accessible from any point of the globe. It is for this reason that we introduce a forward-looking approach for fixed networks, particularly focused on Fixed 6th Generation (F6G) networks. First, we adopt a novel classification scheme for the main F6G services, comprising six categories. This classification is based on the key service requirements, namely latency, capacity, and connectivity. F6G networks differ from those of previous generations (F1G–F5G) in that they concurrently support multiple key requirements. We then propose concrete steps towards transforming the main elements of fixed networks, such as optical transceivers, optical switches, etc., such that they satisfy the new F6G service requirements. Our study categorizes the main networking paradigm of optical switching into two categories, namely ultra-fast and ultra-high capacity switching, tailored to different service categories. With regard to the transceiver physical layer, we propose (a) the use of all-optical processing to mitigate performance barriers of analog-to-digital and digital-to-analog converters (ADC/DAC) and (b) the exploitation of optical multi-band transmission, space division-multiplexing, and the adoption of more efficient modulation formats. [ABSTRACT FROM AUTHOR]

Recently, using iterative decoding algorithms to achieve an interesting bit error rate for spectrally efficient modulation become a necessity for optical transmission, in this paper, we propose a coded modulation scheme based on bit interleaving circular recursive systematic convolutional (CRSC) code and 16-QAM modulation. The proposal system considered as a serial concatenation of a channel encoder, a bit interleaver and M-ary modulator can be flexible easy to implement using a short code length. For a spectral efficiency η = 3 bit / s / H z , the coding gain at a bit error rate of 10−6 is about 8 dB. [ABSTRACT FROM AUTHOR]

In this work, the optical and radiation-shielding characteristics of Sm3+-doped alkaline earth zinc borophosphate glasses with the chemical description 30ZnO-15B2O3-44P2O5-1Sm2O3-10AO [where A = Mg (MZBPS), Ca (C-ZBPS), Sr (S-ZBPS), and Ba (B-ZBPS)] were investigated. The mass attenuation coefficients (μ/ρ) of the glasses were estimated using data generated from the FLUKA Monte Carlo code and from the NIST XCOM database. Optical parameters and neutron cross-sections were obtained using standard theoretical models. The μ/ρ of M-ZBPS, C-ZBPS, S-ZBPS, and B-ZBPS varied in the range of 0.124–21.912 cm2/g, 0.024–22.564 cm2/g, 0.025–22.163 cm2/g, and 0.026–27.150 cm2/g, respectively. Also, the cross-section for fast neutron removal in M-ZBPS, C-ZBPS, S-ZBPS, and B-ZBPS was 0.0956 cm−1, 0.0949 cm−1, 0.0948 cm−1, and 0.0953 cm−1, respectively. The thermal neutron cross-section values were in the order M-ZBPS < C-ZBPS < S-ZBPS < B-ZBPS. The analysis of the optical parameters indicated that the optical density of the glasses increased as the atomic weight of the alkaline earth metal and glass density increased. The X-ZBPS glasses demonstrated good photon-shielding ability and optical properties, making them attractive for modern technical applications. [ABSTRACT FROM AUTHOR]

A detailed theoretical study is conducted on the nonlinear interference in the same-wavelength bidirectional coherent optical fiber communication systems. The Gaussian noise (GN) model used to evaluate nonlinear interference (NLI) in unidirectional systems is applied and extended to bidirectional transmission scenarios. The extended NLI model shows that in a bidirectional transmission communication system, the backward signal almost does not introduce additional nonlinear crosstalk to the forward signal due to the strong walk-off effect between forward and backward transmitted signals. Specifically, the ratio of the nonlinear crosstalk introduced by the forward and backward signals is about 21 dB, which means that the traditional GN model is also applicable in the bidirectional scenario. This conclusion is validated on the platform of a same-wavelength bidirectional coherent optical communication system based on Optisystem software.

The paper presents the results of studies of the influence on the optical transmission of defects in the structure of a sapphire tube grown by the method of A.V. Stepanov, changes in the transparency of a single crystal after mechanical surface treatment, and ultraviolet and radiation exposure. [ABSTRACT FROM AUTHOR]

Optical solitons are solitary waves that propagate without changing shape due to a balance between dispersion and nonlinearity in the medium. Therefore, solitary optical waves are important solutions to nonlinear partial differential equations for modeling pulse propagation in optics. Our work derives new solitary wave solutions to the Kundu–Mukherjee–Naskar (KMN) equation, which governs complex nonlinear optical wave phenomena. Using innovative logarithmic transformation-based analytical techniques, various solution forms are obtained and expressed in closed form via elementary functions. The solutions are validated through direct substitution into the original KMN equation. Our new solutions provide fresh perspectives into the intricate soliton landscape described by this model. Since the KMN equation finds use in fiber optic communications, fluid dynamics, and other domains, these findings have broad implications. The methods showcase promising new pathways for unraveling soliton behaviors by fractional- and integer-order nonlinear models alike. Researchers can build upon these techniques to further advance understanding of the profound mathematical structures underlying real-world physical systems.

Electrodynamics on curved surfaces, as a developed theory, has analogously become a new experimental verification of light transmission in general relativity. The thermal effect of an optical field on a specific 2D surface with constant Gaussian curvature is described in this paper. By considering the analogy between Schrodinger equation and Helmholtz equation under the paraxial approximation, the "quantized" momentum field is generated from the light transmitting on a curved surface by using the effective potential approach, and when decreasing the number of photons until n=0$n = 0$ is thought about, a temperature of Hawking‐like radiation is obtained. The creation process of radiation is also investigated, which is the scattering of light as it travels from a surface of positive curvature to a surface of negative curvature. The derived temperature of radiation field is also equivalent to the event horizon scattering explanation of Hawking radiation. The research may provide new perspectives for Hawking radiation and thermal lens. [ABSTRACT FROM AUTHOR]

The results of studying the optical properties and structure of In2O3 films on Al2O3 (012) substrates deposited by dc-magnetron sputtering are summarized. The films investigated differ in terms of the deposition time, substrate temperature, and the presence of additional heat treatment in air. According to X-ray diffraction measurements, these films show a reflection, which correspond to the (222) plane of the cubic modification of In2O3. Its exact position and half-width depend on the deposition time. The optical properties of the resulting films are explained by the microstructure, which is inhomogeneous in thickness and formed during the sputtering of a target with a relatively low mechanical strength. Thus, the refractive index of the films deposited onto substrates at room temperature increases in the direction from the substrate to the external interface. At a substrate temperature of more than 300°C, the refractive index of the films is uniform, except for a rough layer on the surface. Heat treatment reduces the number of defects in the crystal structure of the films and leads to densification of the film material. As a result, inhomogeneity of the refractive index disappears and the observed band gap for direct transitions decreases. The latter results from a change in the Burstein–Moss shift as a consequence of a decrease in the lattice-defect concentration. The band gap for indirect transitions (corresponding to the true value of the band gap) is insensitive to annealing. [ABSTRACT FROM AUTHOR]

Microwave Photonics systems (MWP) have great potential in latest areas, such as 5G networks, Radar, and Internet of things. In order to have low cost with high bandwidth and less complex Photonic solution, the signal transmission system and the data rate, at which transmission is required, need to be highly efficient, however the factors such as dispersion, losses and non-linearity of the system greatly restrict the performance of the system. Dispersion losses are major portion of all losses occuring in transmission. To compensate the dispersion losses, various technique such as optical delay lines, optical filters, Fiber Bragg gratings can be used in transmission circuit. Along with the dispersion compensation in the system, a right type of filter is also required to ensure right signals at receiving with minimum of losses in strength. This paper analyses different optical filters such as Gaussian, Butterworth, Bessel and Fabry Perot to improve overall system transmission performance and suggests using the dispersion compensation system to minimizes the dispersion losses. The parameters Q-factor, BER rate and Eye heights are compared with changes in fiber length and bandwidth to estimate the best optical filter performance range. Further to that, the paper analyses the different methodologies used to compensate the dispersion and proposes the optimal solution to reduce chromatic dispersion in transmission system. [ABSTRACT FROM AUTHOR]

Over the last decade, intense interest in both basic science and industry has been generated by the physics and uses of fiber-based supercontinuum (SCG) sources. Here, we present our findings about the design and characterization of PCFs based on Tellurite, which combines the following benefits: high nonlinearity, high Birefringence (BR), formation of supercontinuum, coherent normal dispersion profile, and optical range transmission potential with flattened chromatic dispersion profile equal 0.5327 ps/nm km up to a wavelength of around 1.65 μm. Optical properties such as Birefringence, confinement losses (CL), effective refractive index (Neff) and effective mode area (Aeff) are comprehensively examined and explored using the Finite element method (FEM) while employing the solution of nonlinear Schrödinger equations (GNLSE) to profile the temporal and spectral wave propagation. The simulation results show that zero-dispersion is achieved in the proposed PCF design at 1.5 to 1.65 μm. The chosen fiber topology can produce a large supercontinuum spectrum from approximately (1200–2000) nm covering S–C–L bands. The designed PCF will be a good fit for various applications, including biophotonics, Spectroscopy, biosensing, biomedical imaging, and ultra-broadband signal amplification. [ABSTRACT FROM AUTHOR]

Optical transmissions in the wavelength range 600–2700 nm have been done for the Se40As60−xSx (x = 10, 20) chalcogenide thin films. By using these transmission curves, various optical parameters like linear refractive index (n), static refractive index (n0), nonlinear refractive index (n2), oscillator energy (Ed), dispersive energy (E0), band gap energy (Eg), third-order nonlinear optical susceptibility (χ(3)) and γ have been studied. Wemple-Di-Domenico (WDD) relation has been used for dispersion analysis. To know the possibility of nonlinear switching in Se40As60−xSx (x = 10, 20) chalcogenides, nonlinear susceptibility and nonlinear refractive indices are determined by using linear index of refraction and parameters of WDD. On the basis of observed nonlinear optical parameters, the suitability for photonic applications is also discussed. Our experimental results have very good agreement at 10 at.% of S with telecommunication wavelength (~ 1550 nm) at which the maximum optical nonlinearity is found. Due to higher values of nonlinear refractive index, Se40As50S10 is processed better for photonic devices in comparison of Se40As40S20. [ABSTRACT FROM AUTHOR]

• A novel approach for magneto-optical transmission maximization is designed based on nanoring morphology engineering and time dependent magnetic field. • Prior inaccurate association of the dynamics of magneto-optical transmission to magnetic field interactions in literature is corrected. • The renormalization group equations and the scaling theory are utilized for the first time to find the critical concentration for the delocalization-localization transition. • For the first time, the renormalization group equations and the scaling theory are applied quantitatively and for observable quantities. This study leads novel approaches to overcome cluster induced magnetic field formation and the associated reduced light transmission beyond a certain critical magnetic field utilizing the ring morphology and time-varying magnetic field. This hypothesis is challenged by the fabrication of large size ferromagnetic, hematite nanoring and nanodisk samples to increase the coupling constant and the interparticle interactions. The nanoring sample transmission outperformed the nanodisk one by 40–50 % under 0.5 mT, 1–5 kHz time-varying magnetic fields, 12 % in the uniform 0–6.5 mT field, and 27 % in the 40x greater gradient field amplitude by Neodymium magnet. Furthermore, the dominant literature view of the dynamics of optical transmission through ferrofluids is corrected. Moreover, the decrease in the optical transmission in the 350–450 nm band is justified in terms of localization, which is found to occur beyond a certain critical concentration, described by the proposed, experimentally verified power law utilizing the results of the renormalization group equation and scaling theory, for the first time. Therefore, challenging limitation of restriction to their qualitative utilization and non-observable quantities besides the previously doubted matching between the method of invariant imbedding and the renormalization group equation have been all resolved, which is crucial for the entire field of complex media. [ABSTRACT FROM AUTHOR]

In this simulation work, the optical transmission through a 1DTPS considering Si, metamaterial, and SiO2 with different thicknesses for Gigahertz device applications is studied. This discusses tunable band characteristics of the ternary periodic structure with variations in metamaterial thicknesses and incident angle, for TE as well as TM mode, and shows an omni‐directional application. It is noted that the transmission decreases in TE mode with increases in the metamaterial thickness, whereas increases in TM mode. Also, the transmittance in TE mode decreases on increasing the angle of incidence, whereas that increases for TM mode. Hence, it can be mentioned that the structure is a good transmitter of TM waves. The two PBGs increase with increase in the incident angle, for the TE mode; while in TM mode, the first PBG behaves in reverse manner and becomes narrow. For both cases of s and p waves, the PBGs exhibit blue shift with increase in the incident angle. It is to mention that a widen PBG region in the range 6–10 GHz in the first band is common in TE and TM modes at all incident angles, and hence the TPS shows the features of omni‐directional reflector. Such kinds of PCs enable better ideas in designing tunable microwave devices as well as ODR based devices like solar cells. [ABSTRACT FROM AUTHOR]

We suggest that a metal film perforated with two-dimensional (2D) hole arrays can support broadband optical transmission. This phenomenon is based on the impedance matching between the perforated metal film and incoming light waves at oblique incidence. Theoretical formulas for the effective impedance of the hole arrays and Brewster angle of broadband transmission have been derived in the infrared regime, taking account of the field penetration effect on the hole walls. With the numerical simulations, the predicted optical effect has also been demonstrated. Compared with the narrow transmission band due to surface-plasmon polariton resonance, our results present a non-resonant, broadband, and robust transmission channel for the 2D hole arrays. [ABSTRACT FROM AUTHOR]

NTT Network Innovation Center is developing technologies and systems for the practical implementation of an optical transmission network, the key element for implementing the All-Photonics Network (APN), which in turn will support IOWN (the Innovative Optical and Wireless Network). With our nextgeneration optical transmission network, which is an advance release of the APN, we are working to increase speed and capacity to handle growing communication traffic as well as provide open optical interfaces for connecting various systems and devices without photoelectric conversion to enhance the added value provided by optical networks and develop operations and maintenance technologies for these networks. [ABSTRACT FROM AUTHOR]

A possibility was assessed to modify physico-chemical properties of ferronematic mixtures by introducing additional mesogenic and non-mesogenic components. The mixture, consisting of RM734 and DIO at the 70:30 weight ratio of the components, was doped with nematic 5CB and its chiral isomer CB15. This allowed a substantial lowering of the ferronematic temperature range, as well as induction of helical twisting in both nematic (N) and ferronematic (NF) phases. The effects of 5CB and CB15 on the NF to N phase transition were nearly identical, but the isotropic transition temperature decreased more strongly upon addition of CB15. Optical transmission vs. temperature measurements showed lower transmittance in the NF phase, probably due to scattering on the domain boundaries. In the vicinity of the NF → N transition, a noticeable range of anomalously low transmission was noted both on heating and cooling, suggesting a complex character of molecular reorientation features. In the chiral NF (N*F) system, helical twisting was recorded using Grandjean-Cano wedge, with the helical pitch decreasing upon cooling in both N* and N*F phases. In the cooling mode, transient undulations emerged in the N*F phase. The complex picture of the ferronematic transition is supported by POM images taken at different temperatures. [ABSTRACT FROM AUTHOR]

We have started a new research project on a hybrid power generation system consisting of piezoelectric, thermoelectric and solar cell modules. In the first step, we have focused on the antireflection coating based on zinc oxide (ZnO) and metal nanolayers incorporated in solar cells. In layered structure containing ZnO and metal nanoscale layers, we have presented the possibility of increasing wave transmission in the visible region by adding the top and bottom cap layers. The enhancement of optical transmission is very important in improving the performance of sensor protections, solar cells, UV protective films and transparent conductive display panels electrode. It is found that, the structure containing both the top and bottom cap layers (S3) yields larger transmittance than the structures S1 without any cap or S2 just with one cap layer. The maximum transmittance in the visible range can be increased from 33% to 67%. In addition, for the TE mode (TM mode), the maximum value of transmission in the S1 and S2 structures occurs at angles close to normal incidence while in the S3 multilayer it happens around 1 radian, that is, the behavior of the TE mode is the opposite of the TM mode. Also, when the incident angle varies, the band edges experience a blue shift. The amount of TE shift is more pronounced than TM one. Moreover, the metal with higher plasma frequency will move the band gap edges to the higher frequencies. [ABSTRACT FROM AUTHOR]

Over the past fifty years, telecommunications has transformed, in an unprecedented manner, the way we live, work and communicate. For telecommunications, fixed networks are the one pillar and wireless networks the other. The wireless networks and their generations have been extensively investigated in the literature; however, the fixed networks lack a consistent exploration of their evolution. For this purpose, our motivation is to present a review of the evolution of fixed networks in a holistic manner, from various different perspectives, which can assist engineers and students to understand, in a better way, how broadband networks developed and the main features of the current networking environment. Specifically, in this review, we aim to shed light on the most important technologies, standards and milestones of the fixed networks from various perspectives, such as the service perspective, the networking perspective (both access and core part) and the physical layer perspective. Our study follows the timeline of the five generations of fixed networks defined by the European Telecommunications Standards Institute (ETSI) F5G group and discusses the key achievements and limitations of each generation for each different infrastructure layer and segment, designating the most important issues for the most widely-adopted technologies and standards. Finally, our analysis helps to reveal the technical challenges that need to be addressed by the fixed telecom network community, such as energy efficiency, capacity scaling, cost-efficiency, etc., while also revealing potential future directions. [ABSTRACT FROM AUTHOR]

Transparent conducting oxides (TCO) with high electrical conductivity and high visible light transparency are desired for a wide range of high‐impact engineering. Yet, usually, a compromise must be made between conductivity and transparency, limiting the practical application of a TCO to the next level. Furthermore, TCO performance is highly sensitive to composition, so conventional synthesis methods, such as chemical doping, cannot unravel the mysteries of the quantitative structure–performance relationship. Thus, improving the fundamental understanding or creating materials‐by‐design has limited success. Here, a strategy is proposed to modulate the lattice and electronic and optical properties precisely by applying pressure on a TCO. Strikingly, after compression–decompression treatment on the indium titanium oxides (ITiO), a highly transparent and metastable phase with two orders of magnitude enhancement in conductivity is synthesized from an irreversible phase transition. Moreover, this phase possesses previously unattainable filter efficiency on hazardous blue light up to 600 °C, providing potential for healthcare‐related applications with strong thermal stability up to 200 °C. These results demonstrate that pressure engineering is a clean and effective tool for tailoring functional materials that are not achievable by other means, providing an exciting alternative property‐tuning dimension in materials science. [ABSTRACT FROM AUTHOR]

The purpose of this study is to examine the influence of carbon nanodiamonds on the reinforcement and hardening of telluride glasses, as well as to establish the dependence of the strengthening properties and optical characteristics of glasses on CND concentration. According to X-ray diffraction data, the synthesized glasses have an amorphous structure despite the addition of CNDs, and at high concentrations of CNDs, reflections characteristic of small crystalline particles of carbon nanodiamonds are observed. An analysis of the strength properties of glasses depending on the concentration of the CND dopant showed that an increase in the CND concentration to 0.10–0.15 mol. leads to an increase in hardness by 33–50% in comparison with undoped samples. The studies carried out to determine the resistance to external influences found that doping leads to an increase in the resistance of strength characteristics against destruction and embrittlement, and in the case of high concentrations, the change in strength properties is minimal, which indicates a high ceramic stability degree. The study of the radiation resistance of synthesized glasses found that the addition of CNDs leads to an increase in resistance to radiation damage when irradiated with gamma rays, while also maintaining resistance to high radiation doses. The study of the shielding characteristics found that the addition of CNDs is most effective in shielding gamma rays with energies of 130–660 MeV. [ABSTRACT FROM AUTHOR]

Currently, as a universal camera interface, CameraLink is widely used in real-time image processing systems. Furthermore, it is a parallel interface and transmitted by special cable. As a result, the transmission distance of CameraLink interface is limited. In order to extend the transmission distance of CameraLink image data, there are many types of transmission systems based on the serial communication technology. In this paper, a software defined high-speed CameraLink image data transmission system based on pixel clock recovery is proposed to optimize the existing long distance transmission systems of CameraLink image data. Starting from the application background of the CameraLink protocol and field programmable gate array (FPGA) interface, a software defined CameraLink image data access technology is proposed on the camera side to improve the flexibility and adaptability of the transmission system. Meanwhile, the pixel clock recovery method is designed on the frame grabber side to extract the original CameraLink image data according to GTX and phase locking loop (PLL) inside the FPGA, and this method does not need additional circuits which can effectively reduce the transmission system complexity. In addition, according to the GTX bandwidth, the transmission system can support various parallel data which is not limited to CameraLink image data. Experiment results show that the software defined high-speed CameraLink image data transmission system can accurately transmit CameraLink image data by optic fiber and has a guiding significance for other high-speed parallel data transmission system. [ABSTRACT FROM AUTHOR]

In this work, we investigated optical transmission in the wavelength range of 2-14 µm of low-resistance germanium crystals (1-3 Ω·cm) doped with donor and acceptor impurities in the temperature range from 86K to 523K. The values of the attenuation coefficients for investigated crystals are obtained. Minimum attenuation coefficients α of 0,0015-0,0231 cm^(-1) in the temperature range from 86K to 323K are characteristic for germanium single crystals doped with antimony in the range 2,1-11 μm. Studies have shown that the low values of α and the transmittance τ at a wavelength of 3,39 μm for Ge:Bi and Ge:Sb crystals make it possible to use these low-resistance germanium crystals for gas helium-neon lasers at temperatures from 86K to 323K. The temperature changes in the geometry of the crystal surface are investigated at the nanoscale level. It is shown that heating crystalline germanium leads to an increase in the diffuse reflection of radiation from the surface. The possibility of using the low-resistance germanium crystals doped with antimony as elements of infrared optics in the temperature range 86-373K has been demonstrated.

[Display omitted] To study the effect of xenon difluoride as a fluorinating agent on optical properties of glasses in ZBLAN (ZrF 4 –BaF 2 –LaF 3 –AlF 3 –NaF) and HBLAN (HfF 4 –BaF 2 –LaF 3 –AlF 3 –NaF) systems, their optical transmission in the range from UV to IR was investigated. The treatment of the initial fluorides with XeF 2 was shown to lead to a broadening of the transmission region of the obtained glasses both in the UV and IR ranges. Moreover, the treatment of the batch with xenon difluoride leads to the removal of oxygen-containing impurities that absorb in the region of 2.8 μm. [ABSTRACT FROM AUTHOR]

Hydrogen remains an attractive energy carrier because it is abundant, environmentally friendly and has the highest gravimetric energy density of any known substance. Despite this high gravimetric energy density, hydrogen suffers from a low volumetric energy density as a room-temperature gas. To maximize volumetric energy density, storing hydrogen as a magnesium hydride is an efficient and economically viable route, owing to the low weight and high earth abundance of magnesium. A long-lasting obstacle for using magnesium is the high temperature required to release hydrogen once absorbed by magnesium. Although nanoscale magnesium is known to have a favorable effect on the hydrogen desorption temperature, it is not sufficient. In this work, hydrogen absorption and release was investigated by measuring optical changes, which correspond to certain hydrogen concentrations in magnesium nanoparticles. Remarkably, hydrogen desorption from the magnesium nanoparticle assembled thin films at room temperature could be achieved by illumination. This photo-stimulated hydrogen desorption introduces an effective and simple method to enable reversible hydrogen storage in magnesium. The sensitivity of the optical method here used is demonstrated by the fact that even hydrogen absorption from ambient air at 1 ppm has been measured. This work demonstrates that hydrogen can be efficiently stored and released from magnesium nanoparticles using only photons. • Formation of small magnesium nanoparticles with gas aggregation nanoparticle source. • Hydrogenation of magnesium nanoparticles and visualisation of the process. • Photo-stimulated hydrogen desorption. • Hydrogen detection from ambient. [ABSTRACT FROM AUTHOR]