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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Conversion of two Photons with Different Color by a Single Waveguide for Quantum Networks
摘要： Quantum communication would enable opportunities such as secure communication. A quantum network with quantum nodes and quantum channels is necessary for this. The realization of such a quantum network requires the ability to process, store and send photons over long distances. It is not very likely that a single physical system can accomplish all these operations. Therefore, dissimilar quantum systems have to be connected in future quantum networks. Quantum channels are likely to be based on the existing fiber network because it is already well established. The fiber network operates at telecom wavelength (1550 nm) since the losses in fibers are minimal at this wavelength. That is why quantum states at telecom wavelength are needed. Unfortunately, suitable single photon sources and quantum memories are not available at telecom wavelength. Frequency conversion provides the possibility to alter the wavelength of a single photon to another wavelength. With frequency conversion it is possible to convert the VIS/NIR single photon to telecom wavelength and transfer the state over long distances. However, quantum networks do not require single photons but rather entangled photon pairs. Quantum dots are able to generate entangled photon pairs via a biexciton cascade emission. The emitted photons of a cascaded emission usually have slightly different wavelengths. The frequency conversion of the entangled photon pair on a single device would be advantageous for building quantum nodes for real life applications. We present a frequency conversion based on a single lithium niobate waveguide with different local temperatures to convert two different wavelengths on the same chip. The setup consists of a 2100 nm pump laser and a fiber coupled input port for the two biexciton photons (894 nm and 892 nm). These three wavelengths are focused by a lens into a nonlinear crystal with two different local temperatures. Each segment converts one of the incoming wavelengths. The converted signal is coupled into an optical fiber and guided to a filter system, which removes remaining pump light and generated noise photons. A proof of principle experiment was performed with attenuated laser light, where the converted spectrum is shown.
关键词： lithium niobate waveguide,frequency conversion,Quantum communication,entangled photon pairs,quantum network
更新于2025-09-11 14:15:04
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An Integrated Photonic Electric-Field Sensor Utilizing a 1 × 2 YBB Mach-Zehnder Interferometric Modulator with a Titanium-Diffused Lithium Niobate Waveguide and a Dipole Patch Antenna
摘要： We studied photonic electric-?eld sensors using a 1 × 2 YBB-MZI modulator composed of two complementary outputs and a 3 dB directional coupler based on the electro-optic e?ect and titanium di?used lithium–niobate optical waveguides. The measured DC switching voltage and extinction ratio at the wavelength 1.3 μm were ~16.6 V and ~14.7 dB, respectively. The minimum detectable ?elds were ~1.12 V/m and ~3.3 V/m, corresponding to the ~22 dB and ~18 dB dynamic ranges of ~10 MHz and 50 MHz, respectively, for an rf power of 20 dBm. The sensor shows an almost linear response to the applied electric-?eld strength within the range of 0.29 V/m to 29.8 V/m.
关键词： titanium di?used optical channel waveguide,lithium–niobate electro-optic e?ect,photonic electric-?eld sensor,Y-fed balanced-bridge Mach-Zehnder interferometer (YBB-MZI)
更新于2025-09-11 14:15:04
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Design and Optimization of Proton Exchanged Integrated Electro-Optic Modulators in X-Cut Lithium Niobate Thin Film
摘要： In this study, we designed, simulated, and optimized proton exchanged integrated Mach-Zehnder modulators in a 0.5-μm-thick x-cut lithium niobate thin film. The single-mode conditions, the mode distributions, and the optical power distribution of the lithium niobate channel waveguides are discussed and compared in this study. The design parameters of the Y-branch and the separation distances between the electrodes were optimized. The relationship between the half-wave voltage length production of the electro-optic modulators and the thickness of the proton exchanged region was studied.
关键词： Mach-Zehnder,electro-optic modulator,integrated optics devices,proton exchange,lithium niobate thin film
更新于2025-09-11 14:15:04
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Semi-Nonlinear Nanophotonic Waveguides for Highly Efficient Second-Harmonic Generation
摘要： Quadratic optical parametric processes form the foundation for various applications related to classical and quantum frequency conversion, and have attracted significant interest recently in on-chip implementation. These processes rely on phase matching among the interacting guided modes, and refractive index engineering is a primary approach for this purpose. Unfortunately, modal phase-matching approaches developed so far only produce parametric generation with fairly low efficiencies, due to the intrinsic modal mismatch of spatial symmetries. Here, a universal design and operation principle is proposed for highly efficient optical parametric generation on integrated photonic platforms. By breaking the spatial symmetry of the optical nonlinearity of the device, nonlinear parametric interactions can be dramatically enhanced. This principle is then employed to design and fabricate a heterogeneous titanium oxide/lithium niobate nanophotonic waveguide that is able to offer second-harmonic generation with a theoretical normalized conversion efficiency as high as 2900% W?1 cm?2, which enables the measurement of an experimental efficiency of 650% W?1 cm?2, significantly beyond the reach of conventional modal phase-matching approaches. Unlike nonlinearity domain engineering that is material selective, the proposed operation principle can be flexibly applied to any other on-chip quadratic nonlinear platform, to support ultra-highly efficient optical parametric generation.
关键词： lithium niobate,integrated photonics,nonlinear optics,optical parametric generation
更新于2025-09-11 14:15:04
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Electro-optic sensor for static fields
摘要： A sensor has been developed for low frequency and DC electric fields E. The device is capable of measuring fields with ??E = 4 (1) V/cm resolution. It is based on a Y-cut Z-propagation lithium niobate electro-optic crystal. For a particular commercially available bare crystal, we achieved an in air time constant ?? c(air) =6.4(1.8) h for the decay of the electro-optic signal. This enables field monitoring for several hours. As an application, we demonstrated that a constant electric field Eext = 640 V/cm applied via external electrodes to a particular spherical glass container holding an Xe/He gas mixture decays inside this cell with a time constant ??glass E = 2.5(5) h. This is sufficient for the needs of experiments searching for a permanent electric dipole moment in Xe. An integrated electric field sensor has been constructed which is coupled to a light source and light detectors via optical fibers. The sensor head does not contain any electrically conducting material.
关键词： Electric field monitoring,Static fields,Electro-optic sensor,Lithium niobate
更新于2025-09-11 14:15:04
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Determination of the phase relation of a Li La(1?)/3NbO3 system by the slow cooling floating zone method
摘要： The phase relation during cooling of molten LixLa(1?x)/3NbO3 (LLN) was investigated by the slow cooling ?oating zone (SCFZ) method. It was found that LLN melts incongruently into LaNbO4 and a liquid. From the results of an electron probe microanalysis (EPMA) of the SCFZ samples, the solubility limit of Li into LLN was estimated to be x = 0.29, and the distribution coe?cient of Li into LLN appeared to be 0.54. The melting temperatures of LLN with various Li content were determined by di?erential thermal analysis. The results of the present work could be valuable for the growth of high-quality LLN single crystals.
关键词： Lithium compounds,Solubility,Oxides,Slow cooling ?oating zone,Phase diagrams,Lanthanum lithium niobate
更新于2025-09-10 09:29:36
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A Tunable Low-Power Oscillator Based on High-Q Lithium Niobate MEMS Resonators and 65-nm CMOS
摘要： This paper presents a comprehensive guide to co-design piezoelectric RF-micro-electromechanical system (MEMS) resonators and CMOS for enabling voltage-controlled MEMS oscillators (VCMOs) that harness the best benefits out of both platforms. The analysis, focusing on understanding different tradeoffs among the tuning range, power consumption, gain, and phase noise, is generic to any kind of piezoelectric resonators and specific for Colpitts VCMOs. As a result of this paper, the first VCMO based on the heterogeneous integration of a high-Q lithium niobate (LiNbO3) micromechanical resonator and CMOS has been demonstrated. A LiNbO3 resonator array with a series resonance at 171.1 MHz, a Q of 410, and an electromechanically coupling factor of 12.7% is adopted, while the TSMC 65-nm RF LP CMOS technology is used to implement the feedback and tuning circuitry with an active area of 220 × 70 μm2. The frequency tuning of the VCMO is achieved by programming a binary weighted digital capacitor bank and a varactor that are both connected in series to the resonator. The best measured phase noise performance of the VCMO is ?72 and ?153 dBc/Hz at 1 kHz and 10-MHz offsets from 178.23- and 175.83-MHz carriers, respectively. The VCMO consumes a dc current of 60 μA from a 1.2-V supply while realizing a tuning range of 2.4 MHz (～1.4% fractional tuning range). Such VCMOs can be applied to enable ultralow power, low phase noise, and wideband RF signal synthesis for emerging applications in Internet of Things.
关键词： RF-micro-electromechanical system (MEMS),lithium niobate (LiNbO3),phase noise,oscillator,Internet of Things (IoT)
更新于2025-09-10 09:29:36
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5 GHz laterally-excited bulk-wave resonators (XBARs) based on thin platelets of Lithium Niobate
摘要： In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO3, narrow electrodes (500nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave Bulk Acoustic Resonances (XBARs), by utilizing lateral electric fields oriented parallel to the crystalline Y axis and parallel to the plane of the platelet. The resonance frequency of ~4800MHz is determined mainly by the platelet thickness and only weakly depends on the electrode width and the pitch. Simulations show Quality-factors (Q) at resonance and anti-resonance higher than 1000. Measurements of the first fabricated devices show a resonance Q-factor ~300, strong piezoelectric coupling ~25%, (indicated by the large Resonance-antiResonance (RaR) frequency spacing, ~11%) and an impedance at resonance of a few Ohms. The static capacitance of the devices, corresponding to the imaginary part of the impedance, is ~100 Ohms. This device opens the possibility for the development of low-loss, wide band, RF filters in the 3-6 GHz range for 4th and 5th generation (4G/5G) mobile phones. XBARs can be produced using standard optical photolithography and MEMS processes. The 3rd, 5th, 7th, and 9th harmonics were observed, up to 38 GHz, and are also promising for high frequency filter design.
关键词： Lithium Niobate,MEMS,RF filters,XBARs,5G
更新于2025-09-10 09:29:36
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Controllable generation of second-harmonic vortex beams through nonlinear supercell grating
摘要： Lithium niobate (LiNbO3) nonlinear photonic crystals have been widely used in nonlinear wave front modulation for the p-phase difference between the second-harmonic (SH) waves from positive and negative domains. Aided by optimizing algorithms, we can control the diffraction patterns of SH vortex beams by designing nonlinear fork gratings with supercell structures in LiNbO3 crystals. In experiment, we demonstrate that the diffraction energies can be equally distributed in each order or concentrated on certain orders, in agreement with theoretical designs. Potential applications include controllable vortex beam generation, nondestructive parallel vortex detection, and so on.
关键词： quantum information processing,Lithium niobate,optical communication,nonlinear photonic crystals,supercell grating,second-harmonic vortex beams,nonlinear optics
更新于2025-09-09 09:28:46
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CHARACTERIZATION OF NEW NON-STOICHIOMETRIC FERROELECTRIC (Li0.95Cu0.15)Ta0.76Nb0.19O3 AND COMPARATIVE STUDY WITH (Li0.95Cu0.15)Ta0.57Nb0.38O3 AS PHOTOCATALYSTS IN MFCs
摘要： This work investigates the photocatalytic activity of new ferroelectric material with formula (Li0.95Cu0.15)Ta0.76Nb0.19O3 (LT76) in a single chamber microbial fuel cell (MFC) and compare its performance with the similar photocatalyst (Li0.95Cu0.15)Ta0.57Nb0.38O3 (LT57). The photocatalysts LT76 and LT57 were synthesized by ceramic route under the same conditions, with the same starting materials. The ratio Ta/Nb was fixed at 4.0 and 1.5 for LT76 and LT57 respectively. These phases were characterized by different techniques including X-Ray diffraction (XRD), transmission electronic microscopy (TEM), particle size distribution (PSD), differential scanning calorimetric (DSC) and UV-Vis. The new photocatalyst LT76 presents specific surface area about 0.791m2/g and Curie temperature of 1197°C. The photocatalytic efficiency of this material is evaluated in terms of wastewater treatment and electricity generation by power density and removal rate of chemical oxygen demand (COD) in the presence of a light source. The values of the maximum power densities and COD removal were 19.77 mW/m3 and 93% respectively for LT76.
关键词： microbial fuel cell,non-stoichiometry,ferroelectric,Lithium niobate-tantalate,photocatalyst
更新于2025-09-09 09:28:46