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In optical data center networks, the utilization of several software-defined network controllers has been implemented to enhance scalability and reliability. However, during dynamic variations in network traffic, static controller deployment often leads to load imbalance among the controllers. Previous studies have proposed dynamic switch migration as a solution to realize controller load balancing. However, the effectiveness of existing switch migration methods remains insufficient. The load balancing performance of controllers demonstrates limited enhancement following migration, and the migration operations themselves result in supplementary costs. As a result, the issue of switch migration efficiency remains unresolved. To tackle controller load balancing, this research introduces the intelligent controller load balancing (ICLB). ICLB incorporates multiple load metrics to evaluate controller load and selects the ideal target controller based on available resources, leading to enhanced load balancing effectiveness. Moreover, it selects switches while the minimizing migration process, effectively reducing supplementary expenses. Additionally, ICLB can simultaneously manage the workload of multiple controllers during a switch migration process, resulting in enhanced migration efficiency. The outcomes of simulations provide evidence that ICLB offers substantial improvements in controller load balancing performance, along with reduced migration expenses compared to existing solutions. [ABSTRACT FROM AUTHOR]

Silicon-based optical switches are integral to on-chip optical interconnects, and mode-division multiplexing (MDM) technology has enabled modes to function as carriers in routing, further boosting optical switches' link capacity. However, traditional multimode optical switches, which typically use Mach–Zehnder interferometer (MZI) structures and mode (de)multiplexers, are complex and occupy significant physical space. In this paper, we propose and experimentally demonstrate a novel demultiplexing-free dual-mode 3 × 3 thermal-optical switch based on micro-rings (MRs) and mode exchangers (MEs). All MRs are designed to handle TE1 mode, while the ME converts TE0 mode to TE1 mode, enabling separate routing of both modes. Bezier curves are employed to optimize not only the ME, but also the dual-mode 45° and 90° waveguide bends, which facilitate the flexible and compact layout design. Moreover, our structure can support multiple wavelength channels and spacings by adding pairs of MRs, exhibiting strong WDM compatibility. The switch has an ultra-compact footprint of 0.87 × 0.52 mm2. Under both "all-bar" and "all-cross" configurations, its insertion losses (ILs) remain below 8.7 dB at 1,551 nm, with optical signal-to-noise ratios (OSNRs) exceeding 13.0 dB. Also, 32 Gbps data transmission experiments validate the switch's high-speed transmission capability. [ABSTRACT FROM AUTHOR]

To gain a complete understanding of the optical switch that uses phase-change material, Ge2Sb2Te5 (GST), we conducted a simulation considering various physical phenomena related to the switch, such as electrical conduction, Joule heating, heat diffusion, phase change of GST, and light propagation. It was found that the phase state (amorphous and crystalline) of the GST film can be controlled by applying an appropriate pulse voltage to the indium tin oxide (ITO) heater layer, thereby changing the transmittance of the optical switch. Calculations showed that during cooling in the amorphization process, part of the GST film was recrystallized, reducing the transmittance of the optical switch in the ON state. Moreover, the large temperature difference in the GST film during heating was caused by a substantial amount of Joule heat generated in the region distant from the GST film. This difference in distance from the heat-generating region resulted in a considerable temperature difference in the GST film. Thus, herein, we have proposed modified model structures to reduce this temperature difference in the GST film, which can recrystallize during the amorphization process. Calculation using the modified model structures revealed that increasing the thickness of the ITO heater layer, over which the GST film was not placed, can effectively reduce the temperature difference and eventually suppress recrystallization. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate an efficient on-chip thermo-optic (TO) switch based on a photonic crystal nanobeam cavity (PCNC) and a hydrogen-doped indium oxide (IHO) microheater. The small mode volume of the PCNC and the close-range heating through the transparent conductive oxide IHO greatly enhance the coupling between the thermal field and the optical field, increasing the TO tuning efficiency. The experimental results show that the TO tuning efficiency can reach 1.326 nm/mW. And the rise time and fall time are measured to be 3.90 and 2.65 μs, respectively. In addition, compared with the conventional metal microheater, the measured extinction ratios of the switches are close (25.8 dB and 27.6 dB, respectively), indicating that the IHO microheater does not introduce obvious insertion loss. Our demonstration showcases the immense potential of this TO switch as a unit device for on-chip large-scale integrated arrays. [ABSTRACT FROM AUTHOR]

In this paper, we propose an N -bit optical digital-to-analog converter (DAC) by integrating N pairs of 2 × 2 phase change based on-chip photonic switches and 2 × 2 multimode interference (MMI) splitters. An on-chip photonic switch is constructed by integrating a wavelength-selectable racetrack micro-ring resonator with the phase change chalcogenide Ge2Sb2Se4Te (GSST). The GSST-integrated switch utilizes a racetrack resonator configuration for performing the accurate modulation of the resonant wavelength to prevent intercoupling between adjacent units. In order for electrothermal heating of the GSST film to trigger its phase transition for switchable control, an indium tin oxide heater with a bowtie-shaped structure is integrated into the racetrack resonator. Using numerical calculations, we demonstrate that an 8 V voltage pulse at a duration of 300 ns, with an energy consumption of 18.45 nJ, could change the optical state from an OFF state to an ON state. Another 6 V voltage pulse of 250 ns duration, followed by a 4 V pulse of varying duration, with a total energy consumption of 34.78 nJ, can switch the optical state from an ON state to an OFF state. The asymmetric structure of the 2 × 2 MMI shows ultra-high transmittance approaching 50% in the through port (connected to the next order of MMI), enabling the creation of multistage cascaded MMI splitters with an output light power ratio close to 50%. Our results show that this configuration potentially offers a feasible solution for applications of optical DACs. [ABSTRACT FROM AUTHOR]

The traditional telecommunications band performs poorly in harsh weather conditions due to atmospheric absorption. In recent years, researchers have begun to study optical communication through atmospheric windows, and optical switches are an essential component of optical communication. A broadband atmospheric window optical switch was proposed based on Vanadium dioxide and magnetic polaritons (MP). It is formed by the stacking of two metal-dielectric-metal structures. The simulation results show that the modulation depth can reach 98.38%, and the extinction ratio is 17.93 dB. By calculating the magnetic field, we confirmed that the reason for the "off" mode is the coupling between the different MP modes, while the "on" mode is the excitation of MP. The optical switch we proposed may be applied to radiation cooling and optical satellite communication. [ABSTRACT FROM AUTHOR]

An ultra-compact design of all-optical fundamental logic gates like AND, OR in addition with universal logic gates like NAND and NOR using two cascaded symmetrical optical microring resonator has been proposed by utilizing the inherent advantages of optical microring resonator and analysed in Z-domain in the present article. Pump-probe configuration is used for the analysis of the proposed schemes using microring resonator in the Z-domain. The achieved values of extinction ratio, contrast ratio and amplitude modulation are 13.73 dB, 19.10 dB and 0.13 dB, respectively. The calculated value of SNR for the proposed design is 39.63 dB. The bit error rate is nearly 0. The operational speed of our design is 200 Gbps at a very low pump power of 1.19 mW. The simulated results of logic gates are analysed based on estimated performance parameters to establish the novelty of proposed model. [ABSTRACT FROM AUTHOR]

Optical packet switching has gained lot of momentum in last decade due to the advantages of optical fiber over copper cables. Optical switching is beneficial in optical networks which form connections of links and switching nodes. In these high speed networks minimum delay and high throughput are two important parameters which are considered. To minimize network delay shortest path algorithm is used for route selections. In previous studies while choosing shortest path distance among various nodes is considered. In this work we have shown that it is necessary to consider both distance and number of hops while choosing path from source to destination to minimize power per bit used for the transmission. [ABSTRACT FROM AUTHOR]

A variable optical attenuator (VOA) is a crucial component for optical communication, especially for a variable multiplexer (VMUX) and reconfigurable optical add-drop multiplexer (ROADM). With the capacity increasing dramatically, a large-port-count and low-power-consumption VOA array is urgent for an on-chip system. In this paper, we experimentally demonstrate a 16-channel VOA array based on a polymer/silica hybrid waveguide. The proposed array is able to work over C and L bands. The VOA array shows an average attenuation larger than 14.38 dB with a low power consumption of 15.53 mW. The low power consumption makes it possible to integrate silica-based passive devices with a large port count on-chip. [ABSTRACT FROM AUTHOR]

Gallium arsenide (GaAs) semiconductor wires have emerged as potent candidates for nonlinear optical devices, necessitating bandgap engineering for an expanded operational wavelength range. We report the successful growth of strain-mediated GaAs microwires (MWs) with an average diameter of 1.1 μm. The axial tensile strain in these wires, as measured by X-ray diffraction and Raman scattering, ranges from 1.61 % to 1.95 % and from 1.44 % to 2.03 %, respectively. This strain condition significantly reduces the bandgap of GaAs MWs compared to bulk GaAs, enabling a response wavelength extension up to 1.1 μm. Open aperture Z-scan measurements reveal a nonlinear absorption coefficient of −15.9 cm/MW and a third-order magnetic susceptibility of −2.8 × 10−8 esu at 800 nm for these MWs. I-scan measurements further show that the GaAs saturable absorber has a modulation depth of 7.9 % and a nonsaturation loss of 3.3 % at 1050 nm. In laser applications, GaAs MWs have been effectively used as saturable absorbers for achieving Q-switched and dual-wavelength synchronous mode-locking operations in Yb-bulk lasers. These results not only offer new insights into the use of large diameter semiconductor wires but also expand the potential for applications requiring bandgap tuning. [ABSTRACT FROM AUTHOR]

A deep gold-coated sinusoidal grating is proposed as a transducer for label-free real-time biosensing, operating in a new configuration based on the optical switch effect, which produces complementary optical outputs enabling differential and referenced detection. Biosensing experiments are reported for the first time on this platform, using immunoassays involving biospecific pairs consisting of bovine serum albumin and its antibody, and human serum albumin and its antibody. Direct and sandwich immunoassays are demonstrated along with negative controls. A limit of detection of 6 pg/mm2 was obtained. A theoretical model correlating the variation in the differential referenced output optical signal with adlayer growth is presented and supports the experimental results. The proposed detection device operating in the optical switch configuration makes a promising case for point-of-care detection applications because the differential detection of two diffracted orders enables common noise suppression and robust interrogation.

In this paper, a novel plasmonic optical switch based on graphene is designed and simulated with better features and four channels. Each of these channels has an equal width of 20nm which constructed from graphene ribbons spaced at a distance of 30nm from each other. The operation of device is based on the modulation of graphene chemical potential in each channel by using applied voltage. This means that by application of a proper voltage the transmission of input in every channel can be controlled and hence the switching can be occurred. Performance characteristics of this optical switch achieves a relatively high transmission with very low loss at the frequency of 30THz. Also in this structure the amount of crosstalk is remarkably low. This structure has been investigated in different chemical potentials in which one of it’s best status occurs in chemical potential of 0.4eV. All analyses and simulations have been performed in Lumerical and MATLAB.

A monolayer graphene metamaterial structure with a periodic pattern of transverse graphene strip and semi-enclosed graphene square ring is proposed. The dynamically tunable quadruple plasmon-induced transparency (PIT) effect is achieved in the terahertz band. The strong destructive interference between the bright mode and the dark mode, the electric field distributions of the composite graphene structures explain this quadruple-PIT phenomenon well. The results obtained by finite-difference time-domain (FDTD) simulation agree well with those calculated by the coupled mode theory (CMT). By modulating the Fermi level of graphene, two hexa-frequency asynchronous switches and two quadruple-frequency synchronous switches are realized, their maximum modulation depth is 99.9%, and its corresponding insertion loss and extinction ratio are 0.10 dB and 29.90 dB, respectively. These excellent performances exceed many similar graphene metamaterial structures. Therefore, our proposed quadruple-PIT graphene metamaterial structure has potential application value for the design of terahertz multi-channel switches. [ABSTRACT FROM AUTHOR]

An innovative all-optical device is proposed to effectively express the trigonometric ratios of compound angles based on the fascinating intensity dependent changes of refractive index of a nonlinear material. The device has profound applications in numerous domains of research, such as astronomy, oceanography, seismology, civil engineering, electronics, phonetics, medical imaging, and the development of computer music. Optical switch and optical Ternary Encoder play major role in this proposed device. To effectively execute this process, a single constant light source with a standardized intensity level 'I' has been strategically utilized, alongside multiple constant light sources, a beam combiner, and a beam splitter. In this scheme, different value of angles is represented by the different value of standard intensity level to express the trigonometric ratios of compound angles. Furthermore, in the proposed design, the output expression of the trigonometric ratios of compound angles are illustrated as the sum or subtraction of two outputs (2-bit ternary form) of two number of optical Ternary Encoders. As the proposed scheme is fully optical in nature, so this device can be employed in optical computation as well as photonic application. [ABSTRACT FROM AUTHOR]

This study introduces a single-layer patterned graphene metamaterial, composed of a graphene ring (GR), two parallel graphene strips (TPGSs), two vertical graphene strips (TVGSs), and a graphene block (GB), which achieves triple plasmon-induced transparency (TPIT) in the terahertz (THz) frequency range using coupled mode theory (CMT) and the finite-difference time-domain (FDTD) technique. Moreover, a synchronized electro-optical switch with four modulation modes is implemented by dynamically adjusting graphene's Fermi level, exhibiting modulation degrees of amplitude (MDA) of 88.3%, 94.7%, 86.9%, and 89.0% at 1.69 THz, 3.14 THz, 3.95 THz, and 4.67 THz, respectively. In addition, the modes excited by TPGSs and TVGSs interconvert due to the proposed structure's symmetry, accounting for the polarization insensitivity of TPIT. The enhanced MDA and polarization insensitivity of the electro-optical switch presented in this study significantly surpass those of comparable electro-optical switches. As a result, the polarization insensitivity of multiple optical switches to incident light fields offers a promising approach for designing optoelectronic devices. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate an efficient on-chip thermo-optic (TO) switch based on a photonic crystal nanobeam cavity (PCNC) and a hydrogen-doped indium oxide (IHO) microheater. The small mode volume of the PCNC and the close-range heating through the transparent conductive oxide IHO greatly enhance the coupling between the thermal field and the optical field, increasing the TO tuning efficiency. The experimental results show that the TO tuning efficiency can reach 1.326 nm/mW. And the rise time and fall time are measured to be 3.90 and 2.65 μs, respectively. In addition, compared with the conventional metal microheater, the measured extinction ratios of the switches are close (25.8 dB and 27.6 dB, respectively), indicating that the IHO microheater does not introduce obvious insertion loss. Our demonstration showcases the immense potential of this TO switch as a unit device for on-chip large-scale integrated arrays.

Optical communication gained popularity in past few years. Optical communication has many distinct advantages over copper cable based electronic communication. Optical switches are integral part of optical networks which are used for rerouting of packets and also plays important role in contention resolution of the packets. These switch uses fiber delay lines (FDLs) act as optical memory. In past analysis of the switch is done by considering loss, power and noise and finally bit error rate (BER); however dispersion was neglected which is an important parameter in high speed communication. In this paper, design analysis is done by considering dispersion compensation along with optical amplifier noise. [ABSTRACT FROM AUTHOR]

Data centers are facing huge bottlenecks due to the emergence of high-speed data applications. To meet speed requirements, it is proposed to shift the current technologies toward optical communication-enabled data center (DC) devices. This paper discusses the recently proposed optical switch designs and proposes a novel switch design for optical DCs. The architectures proposed in the literature are compared in terms of notable parameters. Finally, proposed switch performance is measured in the network using Monte Carlo simulation and results are obtained in terms of packet loss probability, under a random traffic model while considering both nonperiodized and prioritized packets. [ABSTRACT FROM AUTHOR]

Optical packet switching has gained lot of popularity in last a few years due to its advantages like, large speed, more bandwidth and very less crosstalk. But due to immature optical fabrication and designing technology OPS is still beyond reality. However, many of the optical components are commercialized and some of them are still in laboratory. Thus, for optical switches which are considered as future generation routers, many switch architectures are proposed by using different sets of optical components. This paper presents a detailed review of notable switch designs in past 20 years, and also presents a comprehensive literature survey of the notable papers related to optical packet switch designs. [ABSTRACT FROM AUTHOR]

Mode-division multiplexing (MDM) is a promising multiplexing technique to further improve the transmission capacity of optical communication and on-chip optical interconnection systems. Furthermore, the multimode optical switch is of great importance in the MDM system, since it makes the MDM system more flexible by directly switching multiple spatial signals simultaneously. In this paper, we proposed a mode-independent optical switch based on the graphene–polymer hybrid waveguide platform that could process the TE11, TE12, TE21 and TE22 modes in a few-mode waveguide. The presented switch is independent of the four guided modes, optimizing the buried position of graphene capacitors in the polymer waveguide to regulate the coplanar interaction between the graphene capacitors and spatial modes. The TE11, TE12, TE21 and TE22 modes can be regulated simultaneously by changing the chemical potential of graphene capacitors in a straight waveguide. Our presented switch can enable the independent management of the spatial modes to be more flexible and efficient and has wide application in the MDM transmission systems. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance is an effect widely used for biosensing. Biosensors based on this effect operate in different configurations, including the use of diffraction gratings as couplers. Gratings are highly tunable and are easy to integrate into a fluidic system due to their planar configuration. We discuss the optimization of plasmonic grating couplers for use in a specific sensor configuration based on the optical switch. These gratings present a sinusoidal profile with a high depth/period ratio. Their interaction with a p-polarized light beam results in two significant diffracted orders (the 0th and the −1st), which enable differential measurements cancelling noise due to common fluctuations. The gratings are fabricated by combining laser interference lithography with nanoimprinting in a process that is aligned with the challenges of low-cost mass production. The effects of different grating parameters such as the period, depth and profile are theoretically and experimentally investigated. [ABSTRACT FROM AUTHOR]

A variable optical attenuator (VOA) is a crucial component for optical communication, especially for a variable multiplexer (VMUX) and reconfigurable optical add-drop multiplexer (ROADM). With the capacity increasing dramatically, a large-port-count and low-power-consumption VOA array is urgent for an on-chip system. In this paper, we experimentally demonstrate a 16-channel VOA array based on a polymer/silica hybrid waveguide. The proposed array is able to work over C and L bands. The VOA array shows an average attenuation larger than 14.38 dB with a low power consumption of 15.53 mW. The low power consumption makes it possible to integrate silica-based passive devices with a large port count on-chip.

ABSTRACT: Introduction. The use of liquid crystals is attractive for solving technical problems when creating a new generation of monitors, pressure sensors, seismic activity, determining the level of dry or liquid media, indicators of the concentration of harmful substances due to the small size of devices, low power consumption, simple design, low cost, and easy controllability of liquid crystals by various external fields. Under the action of mechanical shear, the liquid crystal layer is deformed, as a result of which surface polarization occurs. The purpose of the research is to conduct an experimental study of the effect of an electric field on flexopolarization occurring in a thin layer of a liquid crystal to create an acousto-optic shutter. Materials and methods. Nematic liquid crystals 10 – 100 µm thick with homeotropic orientation of molecules were used as materials: n – methoxybenzylidene n – butylaniline; 4 – octyl – 4 – cyanobiphenyl; nitrophenyloctyloxybenzoate; cyanophenyl ester of heptylbenzoic acid. Methods. The experimental setup consisted of a charge-sensitive amplifier with a high input resistance of 10 GΩ and a selective amplifier (2 MΩ). The design of the amplifier made it possible to apply a constant voltage of up to 100 V to its input, as well as linear and synchronous signal detections, which were then fed to the ADC that recorded them. Results and discussion. The behavior of charges induced on the surface of a liquid crystal due to internal mechanisms of molecular-orientation polarization was considered as a function of the magnitude and direction of the external electric field. For this, a liquid-crystal layer (MBBA) was placed in an electric field. The dependences of the first U1ω and second U2ω harmonics, when a positive potential is applied to a deformable plate, reach lower values than with a negative one. The electric field at a positive potential stabilizes the molecules of the polarized layer, and at a negative potential it makes it less stable, which leads in one case to a decrease in the slope angle on the surface, and in the other to an increase, which leads to an increase in the second harmonic. Under weak boundary conditions, a polar deformation occurs in the bulk of the NLC. When the field is applied to the homeotropic layer of NLC (CPEHBA), the value of the second harmonic U2ω increases linearly from the voltage Uc up to the achievement of “saturation”, which is due to an increase in the stabilizing dielectric moment over the viscoelastic one. At low fields (Е ≤ 104 V/cm), the value of U2ω first increases and then decreases due to an increase in the tilt angle of the director relative to the normal to the surface. At low polarizing voltages Uc ≤ 15 V (CPEHBA) dependence U1ω is approximated by a power function of the Uc3 type, at Uc >> 15 V the second harmonic U2ω depends as Uc–1. At low bias voltages, the position of the minima of the values of the first U1ω and second U2ω harmonics (for MBBA and CPEHBA) does not coincide with the zero point along the abscissa at Uc = 0. The harmonics U1ω and U2ω have a maximum when a positive potential is applied to the moving electrode. In the region of positive displacement voltages, the molecules stabilize, while at negative voltages, the molecules are less resistant to orientational perturbations. The value of the second harmonic U2ω sharply decreases with the perturbation frequency. Conclusion. The obtained research results can be used in the development of pressure sensors, seismic sensors for buildings and structures, light modulators, as well as an acoustooptic switch for glass units

A monolayer metamaterial consisting of a rectangle graphene strip and four L-shaped graphene blocks was proposed to achieve a quintuple plasmon-induced transparency (quintuple-PIT). The numerical simulation results based on the finite difference time domain method agree well with the calculated results of the coupled mode theory. By modulating the Fermi energy level of graphene, an octuple-frequency asynchronous switch and a sextuple-frequency synchronous switch are designed and studied, which have excellent amplitude modulation degree (up to 97.7%), extinction ratio (up to 16.41 dB), insertion loss (low to 5.4%), and dephasing time(low to 3.86 ps). Furthermore, the results show that the proposed metamaterials has polarization-sensitive characteristics due to their non-central symmetry. Further research shows that the group index is as high as 604 which has a good slow light effect and can be used for optical storage. Hence, the quintuple-PIT proposed structure in this paper has good application value in the expansion of multi-function optical switches and the research of high-quality optical memory. [ABSTRACT FROM AUTHOR]

This study proposes a terahertz metamaterial structure composed of a silicon–graphene–silicon sandwich, aiming to achieve quadruple plasmon-induced transparency (PIT). This phenomenon arises from the interaction coupling of bright–dark modes within the structure. The results obtained from the coupled mode theory (CMT) calculations align with the simulations ones using the finite difference time domain (FDTD) method. Based on the electric field distributions at the resonant frequencies of the five bright modes, it is found that the energy localizations of the original five bright modes undergo diffusion and transfer under the influence of the dark mode. Additionally, the impact of the Fermi level of graphene on the transmission spectrum is discussed. The results reveal that the modulation depths (MDs) of 94.0%, 92.48%, 93.54%, 96.54%, 97.51%, 92.86%, 94.82%, and 88.20%, with corresponding insertion losses (ILs) of 0.52 dB, 0.98 dB, 1.37 dB, 0.70 dB, 0.43 dB, 0.63 dB, 0.16 dB, and 0.17 dB at the specific frequencies, are obtained, achieving multiple switching effects. This model holds significant potential for applications in versatile modulators and optical switches in the terahertz range. [ABSTRACT FROM AUTHOR]

Although surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique with unbeaten sensitivity, the capabilities of SERS have been not fully utilized in screening applications because throughput of spectrum detection by conventional Raman instruments has been restricted due to their single-point measurement manners. Hence, this paper presents a development of a high throughput Raman screening system that employs a fiber-optic switch and a Raman probe array. In the system, a 785 nm excitation light is directed into the 1 × 8 broadband optical switching device and selectively switched to one of 8 output ports connected to the corresponding Raman probe array to deliver the light to samples under each probe. This optical switching driven probing in sequence allows us to rapidly detect Raman scattering of the multiple (n = 8) samples in array within a short time (~ 28 s) with decent sensitivity (10–7 M). The Raman spectroscopy of the system is validated by comparing the features of Raman spectra obtained from vitamin C tablets with those from a commercial Raman microscope and the detection sensitivity is measured with SERS substrates with different concentrations. Then, feasibility of high throughput screening is tested with a SERS chip array. [ABSTRACT FROM AUTHOR]

This paper pays attention to the broader interest of freezing water droplets in mesotronics, particularly to their use as a new all-optical device platform. Here, we show that a freezing mesoscale water droplet with a low Bond number can behave as fully biocompatible natural microlense to form a photonic hook for application in a tunable temperature-controlled optical switch. We first introduced and demonstrated the basic concepts of an optical switch without changes in the wavelength of illumination of a particle or any moving parts being involved. The principle of the operation of the switch is based on the temperature-induced phase change inside the water droplet's refractive index. The simulation results show that the optical isolation of switched channels for an optical switch with linear dimensions of about 15 λ3 based on a freezing water droplet can reach 10 dB in the process of temperature variation at a fixed wavelength. The use of freezing mesoscale droplets acting as a time-domain photonic hook generator open an intriguing route for optical switching in multifunctional green electronics tools for sensing, integrated optics and optical computers. [ABSTRACT FROM AUTHOR]

We present results of the experimental verification of a concept of the previously proposed all-optical wavelength-selective multichannel switch based on an off-axis Wood zone plate in the millimeter waveband without the use of micromechanical devices or non-linear materials. A laboratory prototype of such a device is considered and its main parameters are discussed. It is shown that the optical isolation of switched channels for the switch based on an off-axis zone plate can reach 15 dB at a frequency difference of 25 GHz in the frequency range of 93 – 136 GHz.

Abstract Research development in the precise control of gene expression in plant cells is an emerging necessity that would lead to the elucidation of gene function in these biological systems. Conventional gene-interfering techniques, such as micro-RNA and short interfering RNA, have limitations in their ability to downregulate gene expression in plants within short time periods. However, nanotechnology provides a promising new avenue with new tools to overcome these challenges. Here, we show that functionalized gold nanoparticles, decorated with sense and antisense oligonucleotides (FANSAO), can serve as a remote-control optical switch for gene interference in photosynthetic plant cells. We demonstrate the potential of employing LEDs as optimal light sources to photothermally dehybridize the oligonucleotides on the surface of metallic nanostructures, consequently inducing regulation of gene expression in plant cells. We show the efficiency of metallic nanoparticles in absorbing light from an LED source and converting it to thermal energy, resulting in a local temperature increase on the surface of the gold nanoparticles. The antisense oligonucleotides are then released due to the opto-thermal heating of the nanobiosystem composed of the metallic nanoparticles and the sense-antisense oligonucleotides. By applying this approach, we silenced the Carnitine Acyl Carnitine Translocase genes at 90.7%, resulting in the accumulation of lipid bodies in microalgae cells. These results exhibit the feasibility of using functionalized gold nanoparticles with sense and antisense oligonucleotides to enhance nucleic acid delivery efficiency and, most importantly, allow for temporal control of gene silencing in plant cells. These nanobiosystems have broad applications in the development and biosynthesis of biofuels, pharmaceuticals, and specialized chemicals.

Dynamically tunable metasurface resonators with high Q factors and excellent sensing performance still lack research. This paper proposes a dual-band symmetry broken induced quasi bound state in the continuum (QBIC) sensor in the near-infrared region based on an asymmetric four-leaf clover-shaped Ge2Sb2Te5 (GST) metasurface. The high-quality transmission spectrum can be tuned by switching the GST crystalline state. Two QBIC magnetic dipole resonances are excited at the amorphous GST state, QBIC Ⅰ (intracavity MD mode) and QBIC Ⅱ (intercavity high-order MD mode). Based on theoretical simulation, the refractive index sensitivity of the QBIC Ⅱ mode (318.05 nm/RIU) is enhanced higher than twice of the QBIC Ⅰ mode (134.03 nm/RIU) owing to the unique electromagnetic field properties. The ultra-high Q factors generated by the two MD resonance modes are 1.1 × 105 (QBIC Ⅰ) and 1.71 × 105 (QBIC Ⅱ) respectively for a small perturbation of the air hole offset distance D = 5 nm. By discussing the effect of the main structure parameters and the analyte thickness on the sensitivity, the optimal parameters are determined. The two strong QBICs supported by the a-GST metasurface are stable when the air hole’s offset from the unit center is at different directions and distances, indicating a good tolerance to fabrication requirements. These results provide a competitive switchable dual-band QBIC metasurface sensor, providing a potential route for tunable metadevices for functional sensing and dynamic control over signals.

The design of an all-optical 3-dB and 10-dB directional coupler that functions as an optical switch if applied a control signal by fusing two photonic crystal waveguides with a coupling wavelength of 14a is accomplished by fusing two waveguides at the center. This fusion is responsible for optical power transfer between the waveguides. The proposed structure was optimized using finite difference time domain and operates at a wavelength of 1550 nm, excluding some wavelengths that were calculated using photonic band gap. It can be used in a variety of telecommunication devices, including multi/demultiplexers for wavelength-division-multiplexing systems, splitters, and optical switches. [ABSTRACT FROM AUTHOR]

Optical switching is an essential part of photonic integrated circuits and the focus of research at the moment. In this research, an optical switch design working on the phenomenon of guided-mode resonances in a 3D photonic-crystal-based structure is reported. The optical-switching mechanism is studied in a dielectric slab-waveguide-based structure operating in the near-infrared range in a telecom window of 1.55 µm. The mechanism is investigated via the interference of two signals, i.e., the data signal and the control signal. The data signal is coupled into the optical structure and filtered utilizing guided-mode resonance, whereas the control signal is index-guided in the optical structure. The amplification or de-amplification of the data signal is controlled by tuning the spectral properties of the optical sources and structural parameters of the device. The parameters are optimized first using a single-cell model with periodic boundary conditions and later in a finite 3D-FDTD model of the device. The numerical design is computed in an open-source Finite Difference Time Domain simulation platform. Optical amplification in the range of 13.75% is achieved in the data signal with a decrease in the linewidth up to 0.0079 µm, achieving a quality factor of 114.58. The proposed device presents great potential in the field of photonic integrated circuits, biomedical technology, and programmable photonics. [ABSTRACT FROM AUTHOR]

The miniaturization of optical switches is a promising prospect with the use of phase-change materials (PCMs), and exploring various strategies to effectively integrate PCMs with integrated optical waveguides represents an intriguing research question. In this study, an ultra-compact integrated optical switch based on PCM is proposed. This device consists of a Ge 2 Sb 2 Te 5 nano-disk and an inverse-designed pixelated sub-wavelength structure. The pixelated sub-wavelength structure offers customized refractive indices that conventional materials or structures cannot achieve, leading to an improved insertion loss (IL) and extinction ratio (ER) performance of the device. Furthermore, this structure enhances the interaction between the optical field and GST, resulting in a reduction of the device size and the inserted GST footprint. With an ultra-compact device footprint of 0.9 µm × 1.5 µm, the simulation results exhibit a low IL of 0.45 dB, and a high ER of 18.0 dB at 1550 nm. Additionally, relevant studies show that this device is able to perform reliably despite minor variations in the manufacturing process. [ABSTRACT FROM AUTHOR]

Reconfigurable optical directed logic circuits (RODLC) aim to perform arbitrary logic operations using the optical switch network, in which the electrical signals regarded as the logic operands are applied to the optical switch to control the propagation of light over time, and the logic operation results are obtained at the output ports of the optical switch network in the form of light. In this paper, a novel RODLC is proposed and experimentally demonstrated by utilizing an optical switch array with the prosperous optical mode division multiplexing (MDM) technology to perform arbitrary logic functions. As a proof of concept, a RODLC with two optical mode (de)multiplexers and twelve thermo-optic microring resonators on a silicon-on-insulator substrate is fabricated based on standard microfabrication technology. To demonstrate its reconfigurability to perform arbitrary logic functions, eight logic operations: NOT, AND, NAND, OR, NOR, XOR, XNOR, as well as one combination operation of four-operand, with the operation speed of 10 Kbps are successfully implemented as examples. The demonstrated RODLC characterized with reconfigurability, scalability, and ability for large-scale integration, will contribute to the flourishing development of optical computing and information processing in large-scale optical hybrid integrated circuits.

Research development in the precise control of gene expression in plant cells is an emerging necessity that would lead to the elucidation of gene function in these biological systems. Conventional gene-interfering techniques, such as micro-RNA and short interfering RNA, have limitations in their ability to downregulate gene expression in plants within short time periods. However, nanotechnology provides a promising new avenue with new tools to overcome these challenges. Here, we show that functionalized gold nanoparticles, decorated with sense and antisense oligonucleotides (FANSAO), can serve as a remote-control optical switch for gene interference in photosynthetic plant cells. We demonstrate the potential of employing LEDs as optimal light sources to photothermally dehybridize the oligonucleotides on the surface of metallic nanostructures, consequently inducing regulation of gene expression in plant cells. We show the efficiency of metallic nanoparticles in absorbing light from an LED source and converting it to thermal energy, resulting in a local temperature increase on the surface of the gold nanoparticles. The antisense oligonucleotides are then released due to the opto-thermal heating of the nanobiosystem composed of the metallic nanoparticles and the sense-antisense oligonucleotides. By applying this approach, we silenced the Carnitine Acyl Carnitine Translocase genes at 90.7%, resulting in the accumulation of lipid bodies in microalgae cells. These results exhibit the feasibility of using functionalized gold nanoparticles with sense and antisense oligonucleotides to enhance nucleic acid delivery efficiency and, most importantly, allow for temporal control of gene silencing in plant cells. These nanobiosystems have broad applications in the development and biosynthesis of biofuels, pharmaceuticals, and specialized chemicals. [ABSTRACT FROM AUTHOR]

A new plasmonic configuration is proposed for application in a sensor and demonstrated for the detection of variations in the bulk refractive index of solutions. The configuration consists of monitoring two diffracted orders resulting from the interaction of a TM-polarized optical beam incident on a grating coupler, operating based on an effect termed the "optical switch". The two monitored diffracted orders enable differential measurements which cancel the drift and perturbations common to both, leading to an improved detection limit, as demonstrated experimentally. The measured switch pattern associated with the grating coupler is in good agreement with theory. Bulk sensing is demonstrated under intensity interrogation via the sequential injection of solutions comprised of glycerol in water into a fluidic cell. A limit of detection of about 10 − 6 RIU was achieved. The optical switch configuration is easy to implement and is cost-effective, yielding a highly promising approach for the sensing and the real-time detection of biological species. [ABSTRACT FROM AUTHOR]

Elastic optical networks (EONs) are a promising technology for the development of flexible and wideband communication systems. The (FSU) frequency slot unit concept is used in this technology to define the bandwidth unit in the frequency domain. The use of a specified number of consecutive FSUs allows bandwidth to be assigned to a data stream in a flexible manner. Nonblocking optical switching networks are required for a successful elastic optical network operation. This article concentrates on the Wavelength Space Wavelength,Space, Wavelength switching network topologies that were previously presented. In comparison to the other architectures, the SSW switching fabric requires fewer Spectrum converters (SCs). n relation to Wavelength Space Wavelength, a prior study clarified that using the meta-slot approach reduces hardware complexity, which is measured by the number of frequency slot unit. A frequency range with one or more (FSUs) is called a meta-slot. The previous study did not discuss how to optimize the meta-slot class sizes, despite the fact that its effectiveness depends on the sizes of the meta-slot classes. Additionally, the use of meta-slots for Space Space Wavelength was not taken into account in the earlier analysis. The optimization of meta-slot class sizes is looked into in this study, and it is shown that this optimization may be modeled as the shortest path issue. For Wavelength Space Wavelength, the previously reported nonblocking conditions are contrasted with the meta-slot scheme optimized using the shortest path model. The outcome attests to the optimized meta-slot scheme's superiority. The distribution of meta-slots among S-switches is also crucial for Space Space Wavelength. The assignment of meta-slots is modeled as a bin-packing problem in the study. Thus, a well-known bin-packing heuristic can be used to find the assignment that is close to ideal. The number of S-switches is calculated for using the optimized meta-slot scheme and previously known nonblocking conditions. The outcome confirms that the meta-slot scheme benefits both Space, Wavelength and Wavelength Space Wavelength.

Mode-division multiplexing (MDM) is a promising multiplexing technique to further improve the transmission capacity of optical communication and on-chip optical interconnection systems. Furthermore, the multimode optical switch is of great importance in the MDM system, since it makes the MDM system more flexible by directly switching multiple spatial signals simultaneously. In this paper, we proposed a mode-independent optical switch based on the graphene–polymer hybrid waveguide platform that could process the TE11, TE12, TE21 and TE22 modes in a few-mode waveguide. The presented switch is independent of the four guided modes, optimizing the buried position of graphene capacitors in the polymer waveguide to regulate the coplanar interaction between the graphene capacitors and spatial modes. The TE11, TE12, TE21 and TE22 modes can be regulated simultaneously by changing the chemical potential of graphene capacitors in a straight waveguide. Our presented switch can enable the independent management of the spatial modes to be more flexible and efficient and has wide application in the MDM transmission systems.

Surface plasmon resonance is an effect widely used for biosensing. Biosensors based on this effect operate in different configurations, including the use of diffraction gratings as couplers. Gratings are highly tunable and are easy to integrate into a fluidic system due to their planar configuration. We discuss the optimization of plasmonic grating couplers for use in a specific sensor configuration based on the optical switch. These gratings present a sinusoidal profile with a high depth/period ratio. Their interaction with a p-polarized light beam results in two significant diffracted orders (the 0th and the −1st), which enable differential measurements cancelling noise due to common fluctuations. The gratings are fabricated by combining laser interference lithography with nanoimprinting in a process that is aligned with the challenges of low-cost mass production. The effects of different grating parameters such as the period, depth and profile are theoretically and experimentally investigated.

This paper presents a microfluidic multifunctional device, which can flexibly change the light input energy by using the effect of Electrowetting-on-Dielectric(EWOD). It can also realize multiple functions of variable aperture, variable optical attenuator and optical switch. The utility model has the advantages of simple structure, small volume, simple operation, wide application, flexibility and low cost. In this paper, the optical characteristics of the proposed microfluidic multifunctional device are analyzed and discussed, and the structure is optimized. The results show that the insertion loss of the proposed microfluidic multifunctional device is as small as only 0.014 dB. The aperture of the liquid variable aperture varies from 0 to 0.506 mm. In theory, the variable optical attenuator has a variable attenuation range of 0 ~100%, and the attenuation can reach 40.2 dB when the applied voltage is 91.1 V. The state microfluidic optical switch is " off" when there is no applied voltage and the state is " on" when the applied voltage is greater than 135 V.

This paper presents a microfluidic multifunctional device, which can flexibly change the light input energy by using the effect of Electrowetting-on-Dielectric(EWOD). It can also realize multiple functions of variable aperture, variable optical attenuator and optical switch. The utility model has the advantages of simple structure, small volume, simple operation, wide application, flexibility and low cost. In this paper, the optical characteristics of the proposed microfluidic multifunctional device are analyzed and discussed, and the structure is optimized. The results show that the insertion loss of the proposed microfluidic multifunctional device is as small as only 0.014 dB. The aperture of the liquid variable aperture varies from 0 to 0.506 mm. In theory, the variable optical attenuator has a variable attenuation range of 0 ~100%, and the attenuation can reach 40.2 dB when the applied voltage is 91.1 V. The state microfluidic optical switch is " off" when there is no applied voltage and the state is " on" when the applied voltage is greater than 135 V.