Electro-optic Switch Research Articles

Semiconductor optical amplifier space switch BER improvement and guard-time reduction through feed-forward filtering

Analysis of the guard-time interval impact on bit error rate (BER) of a linear SOA-based space switch aiming the guard-time reduction is presented, including effects of fiber propagation. The characterization employed feed-forward filtering and optical switching techniques, through several types and lengths of fibers (with and without dispersion compensation). The Wiener filter (with 2 taps) consistently showed a switching performance improvement, with a guard-time (GT) reduction enough to achieve the BER pre-FEC limit. In most configurations the average GT was of 429ps (3 bits GT at 7Gbps). The overall best GT result achieved was using 100mA of SOA bias current and applying the Wiener Filter, resulting in a GT of 286ps (2 bits GT at 7Gbps). The space-switch operating parameters with focus on the bias current and switching technique configuration were also analyzed, aiming at reducing the SOA-based electro-optical space switch guard-time, allowing the achievement of high commutation rates.

Particle size dependence of electro-optical switching in ZrP nano colloid

ABSTRACTAqueous colloid of 2-dimensional (2D) α-ZrP nanoparticles can serve as an excellent material for Kerr devices. We investigate the influence of the particle size on the electro-optical switching for isotropic and biphasic α-ZrP colloids that exhibit stable Kerr effect. Smaller sized α-ZrP colloid has wider range of isotropic and biphasic phases, but since the anisotropic polarizability is approximately proportional to square diameter of particles, the larger sized α-ZrP colloid has higher birefringence at a given concentration. The dynamic response time is also dramatically influenced by the particle size. Smaller sized particle has lower viscosity, and the fall time monotonically increases with increasing particle size. However, the rise time has the minimum at around 0.6 μm owing to the competitive contributions of the anisotropic polarizability and the rotational viscosity. Thus, the particle size in α-ZrP colloid is an important factor to determine the electro-optical performance of a Kerr device based on 2D α-ZrP colloids. These findings will be important in developing electro-optical devices using lyotropic liquid crystal colloids.

A Novel Blocking State of Silicon Electro-Optical Switch Based on Free Carrier Absorption Effect

We propose and experimentally demonstrate a novel blocking state of a silicon electro-optical switch based on free carrier absorption effect. By injecting the holes and electrons into waveguides of a $2\times 2$ Mach-Zehnder interferometer electro-optical switch, both outputs of the switches can be blocked at the same time. The extinction ratios of two outputs of 24-dB and 28-dB are respectively obtained for the blocking state around 1550 nm.

Effect of polymer backbone flexibility on blue phase liquid crystal stabilization

In this study, we synthesized two novel monofunctional acrylate monomers A0DA and A3DA featuring a benzene core and a dodecyl tail, and then investigated their effect on blue phase liquid crystal (BPLC) stabilization. The benzene core is directly linked to the acrylate unit in A0DA, which forms a rigid polymeric backbone. Whereas in A3DA,a propyl spacer is employed to separate the benzene unit from the acrylate group, thereby allowing backbone mobility. By using A0DA as a monofunctional monomer in the BPLC precursor composite, stabilization of BPLC was not seen upon photopolymerization. Interestingly, the use of A3DA showed successful stabilization of BPI lattice structure after polymerization. These results confirm that the origin of stabilization effect of blue phase is the flexibility of A3DA backbone employed; therefore, the polymeric backbone flexibility is suggested to have a major influence on BP stabilization process. Furthermore, we demonstrated a low voltage electro-optical switching of PS-BPLC built on A3DA, while preserving other desirable properties of BPLC. The present study provides useful insight into monomer designs towards BPLC stabilization and enhancement of electro-optical performance.

Analysis of characteristics of a parallel channel microring resonator electro-optic switch array

Based on coupled mode theory, electro-optic modulation theory, and microring resonance theory, a structural model was proposed for a polymer parallel channel microring resonator (MRR) electro-optic switch array, and in the meantime, with a resonance wavelength of 1550 nm, optimization design and simulation analysis were conducted on a eight microrings and nine channels switch array. According to the results of numerical simulation, the free spectral range (FSR) was about 17.71 nm and the 3-dB bandwidth of the output spectrum was about 0.18 nm when the cross-section size of the waveguide core was 1.5 × 1.5 μm2, the confining layer between the waveguide core and the electrode was 2.0 μm thick, the metal electrode was 0.05 μm thick, the coupling gap between the microring and the channel was 0.1 μm, and the microring radius was 12.76 μm. When the voltage of 7 V was applied on microring i of the device in turn, the output optical power Pi of horizontal channel i was the largest, and the output optical power of all the other channels became very small, which meant that the switching function of horizontal channel i was fulfilled. The insertion loss of the device was within a range of 1.39–8.17 dB, and the crosstalk was smaller than −4.8 dB.

Electro-optical full-adder/full-subtractor based on graphene–silicon switches

A compact footprint, low-power consumption, and high-speed operation electro-optical full-adder/full-subtractor based on graphene–silicon electro-optical switches is demonstrated. Each switch consists of a Mach–Zehnder interferometer in which few-layer graphene is embedded in a silicon slot waveguide to construct phase shifters. The presented structure can be used as full-adder and full-subtractor simultaneously. The analysis of various factors such as extinction ratio, power consumption, and operation speed has been presented. As will be shown, the proposed electro-optical switch has a minimum extinction ratio of 36.21 dB, maximum insertion loss about 0.18 dB, high operation speed of 180 GHz, and is able to work with a low applied voltage about 1.4 V. Also, the extinction ratio and insertion loss of the full-adder/full-subtractor are about 30 and 1.5 dB, respectively, for transfer electric modes at telecommunication wavelength of 1.55 μm.

Ultra-fast electro-optic switching control using a soliton pulse within a modified add-drop multiplexer

We have proposed the use of a soliton pulse that propagates within a modified add-drop filter, which is made of a GaAsInP/P material. It is in the form of a Panda-ring resonator, from which a bright/dark soliton pulse is input into a system via an input port. The conversion between bright and dark soliton pulses is introduced at the 3 dB coupler, i.e. the change in phase of π/2. But it is not superimposed each other. The output solitons obtained at the through and drop ports are bight and dark solitons respectively. Both signals can be used to form “ON’ and “OFF” or “1” and “0”, which are useful for the digital bit generation. The switching speed of the system can be improved by employing the two nonlinear side rings. In application, secure output bits can be arranged by using the alternative input solitons or the control ports, where the input bright and dark solitons can be converted into output bits. This means that the output bits can be randomly switched between “1” and “0”, which can be identified by the sender. Moreover, the additional information can be multiplexed via the add port and transmitted in either free space or optical fiber via the whispering gallery mode and through port outputs. Finally, the electro-optic switching can be transferred and the electronic switching by the embedded stacked layers, where the ultrafast switching of light input can lead the ultrafast electrical switching speed. The switching speed of ~ 5 fs and the offset time of ~ 220 fs of the “on” and OFF” are achieved by using the selected ring parameters.

Enhancement the performance of an electro-optic switch by analysis the effect of tensile stress, axial and radial strain

This research presents a technique of an electro optic effect for suggestion model and it optimizes implementation of an electro optics switch using Mat lab simulation program (10). this technique includes design a mathematical model for analysis the effect of tensile stress(y), axial (z)and radial (x)strain on the performance evaluation of an electro optic switch also, it analysis an effect the change of length L and width w of arm of switch. Finally, an active switch optimizes, using the analytical model and considers important device in the modern optical communication system.

A broadband metamaterial absorber based on multi-layer graphene in the terahertz region

A broadband metamaterial absorber, composed of the periodic graphene pattern on SiO2 dielectric with the double layer graphene films inserted in it and all of them backed by metal plan, is proposed and investigated. The simulation results reveal that the wide absorption band can be flexibly tuned between the low-frequency band and the high-frequency band by adjusting graphene’s Fermi level. The absorption can achieve 90% in 5.50–7.10 THz, with Fermi level of graphene is 0.3 eV, while in 6.98–9.10 THz with Fermi level 0.6 eV. Furthermore, the proposed structure can be switched from reflection (>81%) to absorption (>90%) over the whole operation band, when the Fermi level of graphene varies from 0 to 0.6 eV. Besides, the proposed absorber is insensitive to the polarization and can work over a wide range of incident angle. Compared with the previous broadband absorber, our graphene based wideband terahertz absorber can enable a wide application of high performance terahertz devices, including sensors, imaging devices and electro-optic switches.

Ferroelectric Nematic and Ferrielectric Smectic Mesophases in an Achiral Bent-Core Azo Compound.

Here, we report the observation of ferroelectric nematic and ferrielectric smectic mesophases in an achiral bent-core azo compound consisting of nonsymmetrical molecules with a lateral fluoro substitution on one of the wings. These mesophases are enantiotropic in nature with fairly low transition temperatures and wide mesophase ranges. The liquid crystalline properties of this compound are investigated using polarizing optical microscope, differential scanning calorimeter, X-ray diffraction, and electro-optical studies. As revealed by X-ray diffraction measurements, the nematic mesophase is composed of skewed cybotactic clusters and, in the smectic mesophase, the molecules are tilted with respect to the layer normal. The polar order in these mesophases was confirmed by the electro-optical switching and dielectric spectroscopy measurements. The dielectric study in the nematic mesophase shows a single relaxation process at low frequency ( f < 1 kHz) measured in the range 10 Hz to 5 MHz, which is attributed to the collective motion of the molecules within cybotactic clusters. The formation of local polar order in these clusters leads to a ferroelectric-like polar switching in the nematic mesophase. Of particular interest is the fact that the smectic phase exhibits a field induced ferrielectric state, which can be exploited for designing of the potential optical devices due to multistate switching.

Design of an ultra-compact graphene-based integrated microphotonic tunable delay line.

The design of a continuously tunable optical delay line based on a compact graphene-based silicon Bragg grating is reported. High performance, in terms of electro-optical switching time (tswitch < 8 ns), delay range (Δτ = 200 ps), and figure of merit FOM = Δτ/A = 1.54x105 ps/mm2, has been achieved with an ultra-compact device footprint (A ~1.3 x 10-3 mm2), so improving the state-of-the-art of integrated optical delay lines. A continuous and complete tunability of the delay time can be achieved with a very low delay loss ( = 0.03 dB/ps) and a weak power consumption ( = 0.05 mW/ps). A flat bandwidth B = 1.19 GHz has been calculated by exploiting the slow-light effect in the device. This performance makes the proposed optical delay line suitable for several applications in Microwave Photonics (MWP), such as beamsteering/beamforming, for which large delay range, flat and wide bandwidth and small volume are required.

Interfacial behavior of confined mesogens at smectic-C*-water boundary.

In this paper, we have investigated the behavior of mesogens at smectic-C*-water interface confined in a liquid crystal (LC) cell with interfacial geometry. Polarized optical microscopy was used to probe the appearance of various smectic-C* domain patterns at water interface owing to the reorientation of mesogens. The undulated stripe domains observed at the air interface of smectic-C* meniscus vanished as the water entered into the smectic layers and focal conical domain patterns appeared at smectic-C*-water boundary. A spatially variable electro-optical switching of LC molecules was also observed outside the electrode area of the interfacial cell. The electrode region at the interface, as well as on the water side, was damaged upon application of an electric field of magnitude more than 150 kV/m. The change in dielectric parameters of mesogens was extensively studied at interface after evaporating the water. These studies give fundamental insights into smectic-C*-water interface and also will be helpful in fabricating better LC devices for electro-optical and sensing applications.

EDTA and kKCI Doped KDP Solution and Thermodynamics Principle of Crystallization Process

Abstract: Potassium dihydrogen phosphate, KH2PO4 (KDP) crystal is an excellent electro-optical nonlinear optical crystal with large electro-optical nonlinear coefficient, high laser damage threshold, and laser frequency doubling effect, electro-optical effect , Piezoelectric effects and other special features, widely used in inertial confinement fusion engineering (ICF) and electro-optical switching devices. Therefore, its growth mechanism, growth process and performance have been systematically studied. In the process of KDP crystal growth, it is found that the stability of the growth solution is an important factor affecting the quality of crystal growth. Therefore, in recent years, more and more research on the stability of the solution, such as the study of ph, doping, supersaturation, overheating time on the stability of the solution. Among them, the research on the doping is mostly reported, and the research on this aspect is mainly focused on two aspects. On the one hand, it is the study of the stability of the solution under doping, and the other is the effect of doping on the optical quality of the crystal. In fact, the stability of the growth solution and the quality of crystal growth is directly related to the quality, but the existing research to isolate the two researches. Therefore, the experiment will be carried out in the case of double-doped KDP solution stability, KDP crystal growth and crystal optical quality and other experiments, and in-depth analysis of the impact of solution stability and crystal optical quality of the reasons, while the solution stability and The relationship between the optical quality of the crystal is briefly analyzed.

Optimizing effective phase modulation in coupled double quantum well Mach–Zehnder modulators**Project supported by the National Natural Science Foundation of China (Grant No. 11474106), the Natural Science Foundation of Guangdong Province, China (Grant No. 2016A030313439), and the Science and Technology Program of Guangzhou City, China (Grant No. 201707010403).

We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder (MZ) modulator constructed by AlGaAs/GaAs coupled double quantum well (CDQW) waveguides with optical gain. The net change of refractive indexes between two arms of the CDQW MZ modulator is derived by both the electronic polarization method and the normal-surface method. The numerical results show that very large refractive index change over 10−1 can be obtained, making the phase modulation in the CDQW MZ modulator very highly efficient. It is desirable and important that a very small voltage-length product for π phase shift, Vπ × L0 = 0.0226 V⋅mm, is obtained by optimizing bias electric field and CDQW structural parameters, which is about seven times smaller than that in single quantum-well MZ modulators. These properties open an avenue for CDQW nanostructures in device applications such as electro–optical switches and phase modulators.

Electrical switching of birefringence in zirconium phosphate colloids with various solvents.

Even though a graphene-oxide (GO) dispersion is attractive for electro-optical switching devices because of its high Kerr coefficient, it has several limitations such as chemical instability and optical loss due to absorption at visible wavelengths. Here we introduce the use of tetrabutylammonium-tethered α-zirconium phosphate (TBA-ZrP) colloid in various solvents for electro-optical switching devices; the TBA-ZrP colloid is chemically stable and optically transparent. We find that the electrical switching behavior of TBA-ZrP is sensitively dependent on the type of solvent. The TBA-ZrP colloid in acetone exhibits the highest effective Kerr coefficient and the fastest switching time, which is related to the unusual behavior of the viscosity of the TBA-ZrP colloid in acetone. Its viscosity is relatively low and less sensitive to concentration compared to ZrP in other solvents. This indicates that the motion of individual nanoparticles is relatively less restricted in acetone. These findings may be useful in developing electro-optical devices using lyotropic liquid crystal colloids.

Estimation of analytical model for enhancement and implementation of an electro-optic switch

Estimation of analytical model for enhancement and implementation of an electro-optic switch

Electrooptic Switcher Based on Dual Transverse Pockels Effect and Lithium Niobate Crystal

A novel electrooptic switcher is proposed by use of single crystal exhibiting dual transverse Pockels effect, such as lithium niobate crystal. The electrooptic switching operation has been successfully conducted by use of a single lithium niobate crystal with dimensions of $4~\text {mm}\times 4~\text {mm}\times 30~\text {mm}$ and four electrodes. In comparison with the conventional crystal-based electroopticswitcher, the switching voltage of the above electrooptic switcher decreases from 316 to 225 V.

Pool boiling heat transfer enhancement with electrowetting

Electrowetting (EW) has drawn significant research interests in droplet-based microfluidics, and most applications focus on electronic displays, lab-on-a-chip devices and electro-optical switches, etc. This paper presents a new application of EW in enhancing pool boiling heat transfer. The working approach capitalizes on the complimentary roles of hydrophobicity and hydrophilicity played in boiling and takes advantage of the ability of EW to alter the surface wettability dynamically and reversely. In this work, the effects of alternating current EW (ACEW) on the heat transfer characteristics of various boiling regimes, including the onset of nucleate boiling (ONB), fully developed nucleate boiling, and film boiling at critical heat flux (CHF) conditions, are investigated. A synchronized high-speed optical imaging and infrared (IR) thermography approach is taken to obtain simultaneous measurements of the bubble dynamics and the wall temperature and heat flux distributions on the boiling surface. Based on the experimental data, boiling curves are constructed and the boiling heat transfer coefficients (BHTCs) are computed. Comparisons with the boiling characteristics of the baseline surface without ACEW demonstrate the efficacy of ACEW in enhancing the performance of pool boiling heat transfer. Some insights are also offered to understand the physics of the ACEW-enhanced boiling behaviors.

Self-assembled vertical alignment layer of bifunctional amphiphiles for fast electro-optical switching of nematic liquid crystals

ABSTRACTWe present a novel homeotropic alignment method that simultaneously improves the ability of vertical alignment and fast switching of liquid crystals (LCs) in the electro-optical performance. The proposed method utilizes dual self-assembly of 4-(4-heptylphenyl)benzoic acid and 2-carboxyethyl acrylate via hydrogen bonding with ITO substrate. The 4-(4-heptylphenyl)benzoic acid composed of aromatic moieties and alkyl chains induce the homeotropic alignment of the LC molecules. Photopolymerization of 2-carboxylethyl acrylate with a reactive acrylate group under UV irradiation gives the LC molecules a fast response. Our proposed alignment method allows for fabrication of LC devices exhibiting fast LC switching without a conventional polyimide layer.

Estimation of analytical model for enhancement and implementation of an electro-optic switch

This research presents a technique of an electro optic effect for enhancement the an accomplishment of an electro optics switch using Mat lab simulation program . this technique includes design a mathematical model for evaluate the effect of different parameters such as refractive index (n), distance of separation between waveguides (d), length of electrodes (L), relative refractive index (Δn), and switching voltage (V), on the DC bias voltage of an electro optics switch. In this work the investigation of performance of an electro optics switch by analysis of an effect of distance between waveguides and the changing of refractive index on the bias voltage (V), and which optimizes when the wavelength is from 1300 into 1550 nm. Finally, an electro-optic active switch is designed and optimized, using the analytical model and which considers important device in the modern optical communication system.