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Research on optimum slowly-rising driver for electro-optic Q-switched laser
摘要： Electro-optic Q-switch drivers that based on pulse transformer method have been widely used in laser engineering because of the advantages of concise circuits, low supply voltage, low lost, etc., but the long rise time and short pulse duration of the high voltage (HV) pulses have a considerable effect on the Q-switched laser outputs. In this paper, we experimentally investigated the dependence of Q-switched laser outputs on the rise rate of slowly-rising HV pulses in a flash pumped Nd:YAG laser with variable cavity lengths. LiNbO3 Q-switches with various dimensions were used. Based on the experiment results, the optimum slowly-rising HV pulses for any EO Q-switched laser were derived, the only requirement is that voltage near dynamic quarter-wave voltage during the emission of laser pulses. Additionally, the optimum outputs were found to be consistent with the results obtained by using a rapid-switching driver with a rise time of 7 ns. The optimum range of applied voltage was determined to be 0.88 – 1.12 times dynamic quarter-wave voltage.
关键词： Electro-optic Q-switching,Lithium niobate crystal,Slow rise time,Q-switch driver,Pulsed laser
更新于2025-09-19 17:13:59
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Hybrid photonic-plasmonic electro-optic modulator for optical ring network-on-chip
摘要： One of the most essential components in an optical network-on-chip (ONoC) is the electro-optic modulator. Mach-Zehnder and micro-ring resonator electro-optic modulators are widely used in ONoC, and conventional silicon-based modulators have large footprints and low modulation rates and lack thermal stability. In this paper, a new electro-optic modulator based on surface plasmon polariton (SPP) is proposed, and indium tin oxide (ITO) is utilized as a conducting transparent oxide (TCO) material in the electro-optic modulator. The modulated optical signal is suitable for ONoC with architectures such as optical ring network-on-chip (ORNoC). When the wavelength is 1550 nm, the average coupling efficiency is over 70%, the extinction ratio of the electro-optic modulator is -14.1 dB, and the insertion loss is 2.1 dB. In addition, the size of the modulator is less than 8.50 μm×1.6 μm, and the modulation operating bandwidth is up to 0.7171 Tbit/S. When the wave division multiplex (WDM) mode is used, the operating bandwidth is up to 2.1 Tbit/S, and the energy consumption per bit (E) is 5.7211 fJ/bit. All of the above results were obtained from 3D-FDTD Simulation Software and MATLAB.
关键词： electro-optic modulator,ORNoC,optical network-on-chip,transparent conductive oxide,surface plasmon polaritons
更新于2025-09-19 17:13:59
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Silicon p-n-Diode Based Electro-Optic Modulators
摘要： A method for forming p–n-diode based silicon electro-optic modulators using local oxidation is tested. It is shown that the local oxidation of silicon allows forming a rib waveguide as a smoothed trapezoid, in contrast to the classical technique of creating a rib waveguide by plasma-chemical etching. The main advantages of the approach used are described: controllability and reproducibility of critical design parameters of the modulators (width and height of the waveguide rib), low surface roughness, and the possibility of using approaches to forming a modulating p–n-diode of combined type in a rib waveguide, which are standard for planar technologies.
关键词： silicon-on-insulator,electro-optic modulator,waveguide
更新于2025-09-19 17:13:59
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Electro-optically tunable racetrack dual microring resonator with a high quality factor based on a Lithium Niobate-on-insulator
摘要： We propose and analyse a novel electro-optically tunable racetrack dual microring resonator with a high Q factor based on a lithium niobate-on-insulator. Using the transfer matrix method, the field transmission and attenuation of the resonator are comparatively investigated to obtain optimised coupling parameters. The enhanced Q value at the resonant wavelength of the inner ring can reach 3.873 × 106, and the blue shift of the resonant wavelength is approximately 16 nm when the applied voltages fall in a ±150 V range resulting in an electro-optic tuning rate of 0.0526 nm/V. The designed resonator presented here exhibits high performance and may offer more potential applications for lithium niobate nanophotonic devices.
关键词： electro-optic effect,lithium niobate-on-insulator,optical microring resonator,quality factor
更新于2025-09-19 17:13:59
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Design and Electro-optic investigations of de Vries smectics for exhibiting broad temperature ranges of SmA* and SmC* phases and fast electro-optic switching
摘要： In this paper we report on the design, synthesis and characterisation of two new ferroelectric liquid crystalline compounds based on using cores of (i) 5-phenyl-pyrimidine benzene and (ii) 5-phenyl-pyrimidine benzoate terminated by achiral trisiloxane chain, and chiral (S) alkyl chain on the opposite ends of their respective mesogens. These compounds exhibit broad temperature ranges of SmA* and SmC* phases, whereas the latter exists at room temperature down to 11 oC. This is one of the desirable features of the compounds for perspective applications in devices. In both compounds, the differential scanning calorimetry shows a weak first order SmA*-SmC* transition. This observation is supported by determining the critical exponent of the power law as ~0.2 that describes the dependence of the tilt angle and the spontaneous polarization on temperature. The two compounds show excellent de Vries characteristics in terms of the layer shrinkage in SmC*, the maximum shrinkage in both cases is ~ 1.5%. Furthermore (i) the birefringence decreases with a reduction in temperature instead of increasing in SmA*, and (ii) a large field-induced birefringence is observed in SmA* close to the SmA*-SmC* transition temperature, (iii) the maximum birefringence measured is much lower than of a typical FLC material. The characteristics of these compounds when compared to a conventional/typical ferroelectric liquid crystalline mixture show that these materials surpass in performance in terms of having a (i) wider temperature range of both SmA* and SmC* phases and (ii) higher switching speed. The layer thickness in SmA* and SmC* is measured using the techniques of (a) small-angle X ray diffraction, and the (b) optical interferometry of free standing smectic films. A comparison of the results is used to determine an exceptionally useful result of the apparent tilt angle as a function of temperature in SmA* without the need of applying the electric field across the cell.
关键词： de Vries characteristics,electro-optic switching,SmA* and SmC* phases,ferroelectric liquid crystalline compounds,birefringence
更新于2025-09-19 17:13:59
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Three-dimensional polarization ray tracing in electro-optic crystals
摘要： Electro-optic crystals are extensively utilized to manipulate polarized light. In this paper, a general and accurate three-dimensional polarization ray tracing calculus for characterizing the evolution of polarization state in electro-optic crystals is reported for the first time. The analytical formulas of the parameters describing the propagation properties of the light passing through an electro-optical crystal with an arbitrary incident direction are derived. The partial interference between the divergent light beams is considered in the proposed calculus. Both experiments and calculations on an electro-optic modulator based on a lithium niobate crystal over the azimuth angle of 0?-360? and the incidence angle of 0?-3? are presented as an example. The experimental results show very good agreement with the theoretical results.
关键词： Polarization,Electro-optic crystals,Lithium niobate,Ray tracing
更新于2025-09-19 17:13:59
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Simultaneous generation of laser sources in S, C and L bands through four-wave mixing of electro-optic frequency combs
摘要： Increasing bandwidth demands necessitate the use of several carriers in wavelength division multiplexing. Conventionally, carrier wavelengths were generated by individual lasers which suffer from large area and power requirements with scaling of number of carriers. We demonstrate simultaneous generation of over 316 wavelengths in S, C and L bands from two lasers spaced 4 nm apart in the C-band. Electro-optic modulators initially scale each laser to 9 lines (in 20 dB bandwidth). The electro-optic frequency combs are power scaled to ~800 mW and undergo cascaded four-wave mixing in highly nonlinear fiber to generate wavelengths in the three bands. The number of lines in 20 dB bandwidth in S, C and L bands are 88, 160 and 68 respectively. This system can also be used for RF arbitrary waveform generation.
关键词： four-wave mixing,electro-optic modulators,wavelength division multiplexing,highly nonlinear fibers
更新于2025-09-19 17:13:59
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Electro-optic evolution driven by static and relaxational nano ferroelectric domains in KTa <sub/>1a??x</sub> Nb <sub/>x</sub> O <sub/>3</sub>
摘要： Polar nano-regions (PNRs), whose evolution and response mechanism are unclear, were identified to be responsible for the pivotal large electro-optic (EO) coe?cients near the TC in KTa1(cid:2)xNbxO3 (KTN) crystals. To investigate this phenomenon, the temperature dependence of its Raman spectrum, and of its linear e?ective and quadratic EO coe?cients, were investigated. Our results showed that both the relaxational nano-domains driven by biased electric fields under ordered static domains and strong anisotropy determined by the deformation of the NbO6/TaO6 realize enhancements of EO properties in the vicinity of Tf. We expect this understanding of the dynamic EO characteristics to be valuable for developing photonic devices and for providing a basis for exploring the origin of giant EO and piezoelectric e?ects in disordered ferroelectrics and relaxors.
关键词： KTa1(cid:2)xNbxO3,Ferroelectrics,Polar nano-regions,Raman spectrum,Electro-optic
更新于2025-09-19 17:13:59
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Determination of the electric field and its Hilbert transform in femtosecond electro-optic sampling
摘要： We demonstrate time-domain sampling of mid-infrared electric ?eld transients and their conjugate counterparts exploiting the dynamical Pockels effect. To this end, the complete polarization change of few-femtosecond probe pulses is studied. An intuitive picture based on a phasor representation is established before gaining quantitative understanding in experiment and theory. In the standard version of electro-optic sampling, the electric ?eld is determined by analyzing the change of ellipticity of the probe polarization. Beyond this, we ?nd that a temporal gradient of the input electric ?eld manifests itself in a rotation of the polarization ellipsoid of the probe. The relative contribution of sum- and difference-frequency mixing processes and their spectral distribution over the near-infrared probe bandwidth are identi?ed as key aspects. If one of these processes dominates, detecting ellipticity changes and polarization rotation as a function of time delay results in two wave forms which are Hilbert transforms of each other. Such conditions may be achieved by angle phase matching in birefringent materials or spectral ?ltering of the probe after the nonlinear interaction. In this case, a static phase introduced by birefringence or re?ection at metallic mirrors results in a speci?c phase shift of both time traces with respect to the input electric ?eld. Contributions from sum- and difference-frequency generation are found to be equivalent when using electro-optic sensors with isotropic refractive index. Polarization rotations in the low- and high-frequency parts of the probe then tend to cancel out. In this limit, spurious additional phase shifts do not change the phase of the detected transients. This fact leads to a robust recovery of the carrier-envelope phase of the input wave form. Clarifying the role of imperfections of superachromatic phase retarders completes our survey on proper determination of the electric ?eld and its conjugate variable.
关键词： polarization rotation,sum-frequency generation,difference-frequency generation,electro-optic sampling,Pockels effect,mid-infrared,Hilbert transform
更新于2025-09-19 17:13:59
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A compact 120??GHz monolithic silicon-on-silica electro-optic modulator
摘要： A novel electro-optic modulator using the silicon-on-silica platform is proposed. The modulator utilizes a modified version of the gate-all-around switching mechanism which is well-known in MOSFET transistors. The waveguide silicon core is surrounded by oxide and metal to increase the effect of the applied voltage in charge depletion and accumulation and hence the optical phase shift. The modulator features a very high switching speed of 120 GHz, thanks to its very low capacitance, with a total insertion loss of 4.6 dB and a phase-shifter length of 500 μm. The proposed modulator can therefore serve in high speed applications such as the backbone circuits of the new 5G telecommunications networks.
关键词： Integrated optics,Electro-optic modulators,Silicon photonics
更新于2025-09-19 17:13:59