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Graphene-Incorporated Soft Capacitor for Mechanically-Adjustable Electro-Optic Modulators
摘要： In addition to ultra-high capacity and speed in data management, future communication networks require enhanced performance via system reconfigurability under limited resources. Extremely high-speed operation renders optical data managing devices as excellent candidates to hybridize with current electronic devices; however, they still need tunability for system reconfiguration in an integrated scheme. We demonstrate an efficient electro-optic (EO) modulator that is mechanically tunable on a multiple optical waveguide system functioned with a soft capacitor structure incorporating graphene and poly(methyl methacrylate) (PMMA). The flexible capacitor that generates optical signals by temporal light absorption depending on electrical signals can be mechanically detached and re-attached from and onto a rigid surface of the waveguide. It provides either the on or off state of the modulating operation, and enables switching of the working waveguides following the reconfigured data routes. Quality-controlled graphene mainly provides the EO operation, and PMMA plays an important role as both the flexible dielectric layer in the capacitor and the passivation layer for graphene protection. The modulation effects of the manually prepared graphene-PMMA capacitor mechanically adjusted onto a side-polished optical fiber (D-shaped fiber) are investigated in terms of the extinction ratio (ER) of the transmitting light and the operational bandwidth. We successfully display an ER of the modulator up to 19.8 dB with a voltage control ranging from -50 V to 50 V. Its stable operation is verified with a modulation speed up to 2.5 MHz.
关键词： electro-optic modulator,mechanical tuning,graphene,tunable modulator,soft material
更新于2025-11-28 14:24:03
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Measuring effective electro-optic coefficient at 1040?nm by spectral intensity modulation with THz time-domain spectroscopy
摘要： We report a single method for measuring the e?ective electro-optics (EO) coe?cient only by spectral intensity modulation with a terahertz time-domain spectroscopy (THz-TDS) device. Compared with conventional methods, the measuring device based on THz-TDS by probing the spectral intensity modulation is simple, rapid, and highly sensitive. It does not require special preparation process, electrode contact or applying high voltage on the sensor samples. The EO coe?cients of four kinds of materials, namely, ZnTe and GaP crystals, DAST wafer and GaSe ?lm, are measured at 1040 nm. The results showed good agreement with literature data by the conventional methods.
关键词： E?ective electro-optic coe?cient,EO materials,Spectral intensity modulation,THz-TDS
更新于2025-11-28 14:24:03
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Resonant electro-optic frequency comb
摘要： High-speed optical telecommunication is enabled by wavelength-division multiplexing, whereby hundreds of individually stabilized lasers encode information within a single-mode optical fibre. Higher bandwidths require higher total optical power, but the power sent into the fibre is limited by optical nonlinearities within the fibre, and energy consumption by the light sources starts to become a substantial cost factor. Optical frequency combs have been suggested to remedy this problem by generating numerous discrete, equidistant laser lines within a monolithic device; however, at present their stability and coherence allow them to operate only within small parameter ranges. Here we show that a broadband frequency comb realized through the electro-optic effect within a high-quality whispering-gallery-mode resonator can operate at low microwave and optical powers. Unlike the usual third-order Kerr nonlinear optical frequency combs, our combs rely on the second-order nonlinear effect, which is much more efficient. Our result uses a fixed microwave signal that is mixed with an optical-pump signal to generate a coherent frequency comb with a precisely determined carrier separation. The resonant enhancement enables us to work with microwave powers that are three orders of magnitude lower than those in commercially available devices. We emphasize the practical relevance of our results to high rates of data communication. To circumvent the limitations imposed by nonlinear effects in optical communication fibres, one has to solve two problems: to provide a compact and fully integrated, yet high-quality and coherent, frequency comb generator; and to calculate nonlinear signal propagation in real time. We report a solution to the first problem.
关键词： optical telecommunication,electro-optic effect,optical frequency combs,wavelength-division multiplexing,whispering-gallery-mode resonator
更新于2025-11-28 14:23:57
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Synthesis, characterization and comparative studies of nonlinear optical chromophores with rod-like, Y-shaped and X-shaped configurations
摘要： A series of highly polarizable nonlinear optical (NLO) chromophores ZJ1-4 with three different configurations, including rod-like, Y-shaped and X-shaped configurations, have been synthesized with facile routes and systematically studied. The resulted chromophores exhibited excellent thermal stabilities. The relationship between molecular configuration and NLO activity was analyzed from the theoretical calculation and experiment. The molecular dipole moment of chromophore ZJ4 was enhanced by X-shaped structure with two acceptors. Meanwhile, the tendency of forming anti-parallel interactions could be inhibited by disk-like molecular configuration with larger steric hindrance. ZJ4 exhibits the largest EO activity of 103 pm/V, and both of molecular and material NLO properties are improved for the chromophore ZJ4 with the X-shaped configuration compared with corresponding benchmark chromophore ZJ1 with rod-like molecular structure.
关键词： shape,nonlinear optic,electro-optic,structure-property relationship,chromophores
更新于2025-09-23 15:23:52
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Graphene-Augmented Polymer Stabilization: Drastically Reduced and Temperature-Independent Threshold and Improved Contrast Liquid Crystal Device
摘要： Polymers reinforced with nano?llers, especially graphene in recent times, have continued to attract attention to realize novel materials that are cheap and also have better properties. At a di?erent level, encapsulating liquid crystals (LCs) in polymer networks not only adds mechanical strength, but could also result in device-based refractive index mismatch. Here, we describe a novel strategy combining the best of both these concepts to create graphene-incorporated polymer-stabilized LC (PSLC) devices. The presence of graphene associated with the virtual surface of the polymer network besides introducing distinct morphological changes to the polymer architecture as seen by electron microscopy brings out several advantages for the PSLC characteristics, which include 7-fold lowered critical voltage, its temperature invariance, and enhanced contrast ratio between ?eld-o? scattering/?eld-on transparent states. The results bring to fore the importance of working at very-dilute-concentration limits of the ?ller nanoparticles in augmenting the desired properties. These observations open up a new vista for polymer?graphene composites in the area of device engineering, including substrate-free smart windows.
关键词： temperature invariance,graphene,electro-optic properties,threshold voltage,polymer-stabilized liquid crystals
更新于2025-09-23 15:23:52
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Comparison between Ferromagnetic and Ferroelectric Optical Switch Devices in Terms of the Response to the Electric Field
摘要： In this work we have studied the electro-optical effect of two types of ferronematic nanoparticles. The first sample doped with magnetic material Fe3O4 and the second sample doped with a ferroelectric material SbSI. The difference in the two types of material that has been vaccinated led to different values of electro-optic properties because of the different susceptibility of materials. We have noticed that the material SbSI was more responsive to the applied electric field due to the nature of the constituent material (electric material) than the Fe3O4 ferromagnetic. The response time for the material SbSI is less than the response time of the ferromagnetic Fe3O4, that led to make the material SbSI best in the optical switch applications.
关键词： Electro-Optic Properties,Response Time,Fall Time,Rise Time,Ferronematic (FN),Threshold Voltage
更新于2025-09-23 15:22:29
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High-speed Optical-beam Scanning by an Optical Phased Array using Electro-optic Polymer Waveguides
摘要： Optical phased arrays (OPAs), which manipulate an optical beam by controlling the phase of light, are optical devices characterized by high speed, small size, light weight, and high reliability that make various applications possible. In this study, an eight-channel-waveguide OPA using an electro-optic (EO) polymer for phase control was fabricated. Very high-speed optical beam scanning with a frequency of 2 MHz was demonstrated by applying a driving waveform superimposing sinusoidal and rectangular-wave voltages. Furthermore, the EO polymer OPA can be operated with a low total-operation power consumption of 0.38 mW at a scanning speed of 500 kHz.
关键词： Optical phased array,electro-optic polymer,optical waveguides
更新于2025-09-23 15:21:01
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Recent advances with electro-optic polymers
摘要： In recent years the electro-optic polymers emerged as an important branch of material science. This growth and interest is fundamentally motivated by practical application of these materials in second-order nonlinear optics and in waveguiding configuration. Indeed, these materials marry excellent optical quality of amorphous r bonded polymers with enhanced first hyperpolarizability of imbedded organic nonlinear optical molecules. Although a big progress was achieved with them, concerning particularly the science, understanding and applications, some problems remain still incompletely solved, particularly the stability of induced polar order by the application of external electric field and the molecule aggregation. In this review paper we recall techniques of thin film fabrication, poling, characterization of NLO properties and discuss more precisely problems of molecule aggregation as well as the temporal decay of polar order. A novel 3D second-order NLO chromophores, namely the [2] paracyclophanes, which may help to limit the aggregation, are proposed. We show, in particular, that this molecule can be poled in doped PMMA thin films. Practical applications of electro-optic polymers are also reviewed and discussed.
关键词： pockels effect,electro-optic polymers,electric field poling,first hyperpolarizability,second harmonic generation,[2] paracyclophane,functionalized polymers
更新于2025-09-23 15:21:01
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Integrated electro-optic modulators in x-cut lithium niobate thin film
摘要： Integrated optics is poised to revolutionize several data communication applications. The development of high performance electro-optic modulators is essential for the technology to be viable. In this paper, single-mode electro-optic modulators in x-cut lithium niobate thin film are designed, simulated, and analyzed. The single-mode conditions of lithium niobate ridge waveguides are analyzed in detail. The design parameters of Y-branch and separation distances between electrodes and ridge waveguides are optimized. The half-wave voltage of the electro-optic modulator with device lengths of 10 mm is determined. The half-wave voltage-length product is about 2.2 V·cm, indicating the efficient electric-optical modulation. This study is helpful for understand of electro-optic modulator structures in lithium niobate thin film, as well as for the fabrication of high-performance and multifunctional electro-optic modulation devices.
关键词： Electro-optic modulator,Lithium niobate thin film,Waveguide devices,Integrated optics
更新于2025-09-23 15:21:01
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Electro-absorption and Electro-optic Characterization of L-Band InAs/InP Quantum-dash Waveguide
摘要： Electro-absorption and electro-optic characteristics of InAs/InP quantum-dash active region-based waveguide, emitting at ~1600 nm is investigated. Two major peaks were observed in the change of absorption spectrum with a maximum value of 7070 cm-1 at a bias voltage of -8V with an excellent uniform extinction ratio of ~15 dB across the wavelength range of operation (1460-1620 nm). The effect of temperature on electro-absorption (EA) measurement suggest a strong influence resulting in merging of two major change of absorption spectrum peaks with higher temperature. Furthermore, electro-optic measurements indicate a change in refractive index and its efficiency values of ~2.9×10-4 and ~0.5×10-4 V-1, respectively, hence exhibiting a low chirping factor of 0.9 and 1.5 at bias voltages of -2 V and -4 V, respectively. As a quasi-three-dimensionally confined structure possessing both quantum well- and quantum dot-like features, the quantum dash waveguide showed superior electro-absorption and electro-optic properties compared to quantum dots and close to that of quantum wells, while attaining low chirp and broad wavelength range of operation. This paves a way for potential realization of quantum dash-based EA and electro-optic modulator for future optical access networks, particularly operating in wide C- to L-band region.
关键词： quantum-dot,modulators,electro-optic,electro-absorption,Quantum-dash
更新于2025-09-23 15:19:57