Search

In recent decades, photoluminescence properties of single molecules and ions have opened new possibilities for studies on smaller size scales, below the light-diffraction limit. In this thesis, the advantages of such single photon emitters were harnessed and studied mainly in the field of biophysics, but also, in investigations within solid state photonics. The first aspect encompassed studies on extracellular vesicles (EVs) and nanovesicles derived from red blood cell (RBC) membranes which were bioengineered for drug delivery applications. RBC-derived vesicles demonstrated high biocompatibility and low immunogenicity, offering superior production scalability over physiological EVs. However, thorough physical characterizations of such nanovesicles are yet to be developed. Such investigations are essential for their clinical deployment, for therapeutic and diagnostic purposes. Initially, the morphology and size-stability of vesicles were investigated by applying atomic force microscopy and dynamic light scattering. These studies demonstrated the size heterogeneity and agglomeration tendencies of the vesicles. Comparative studies on physiological EVs revealed a higher size stability, while RBC-produced vesicles showed about 50 % reversible agglomerations. Secondly, a dual-colour coincident fluorescent burst (DC-CFB) experimental analysis technique was developed. DC-CFB was then used to characterize and profile the cargo-loading yields of bioengineered nanovesicles, overcoming challenges related to their small size (below the diffraction limit), their inherent heterogeneity, and the presence of free, non-encapsulated cargoes. The developed methodology was then applied to explore the loading with relatively small single nucleotides (dUTP) as well as larger antibody (Ab) molecules, motivated by the prospective role of such EVs and EV-mimetic bioengineered vesicles as nanocarriers of therapeutic drugs. The studies demonstrated consistent average loading yields of around 1, Under de senaste årtiondena har fotoluminescens-egenskaper hos enskilda molekyler och joner öppnat nya möjligheter till studier på mindre storleksskalor, under ljusdiffraktionsgränsen. I den här avhandlingen utnyttjades och studerades fördelarna med sådana enskilda foton-källor främst inom biofysik, men också för undersökningar inom fasta tillståndets fotonik. Det första aspekten omfattade studier av extracellulära vesiklar (EVs) och nanovesiklar, genererade från röda blodkroppars (RBC) membran, och utformade för applikationer rörande leverans av läkemedel i kroppen. De RBC-genererade vesiklarna uppvisade hög biokompatibilitet och låg immunogenicitet och erbjöd en överlägsen uppskalbarhet för produktion jämfört med fysiologiska EVs. Emellertid måste noggranna fysiska karakteriseringar av sådana nanovesiklar ännu utvecklas. Sådana undersökningar är nödvändiga för att i förlängningen kunna använda denna typ av vesiklar klinikst, för terapeutiska och diagnostiska ändamål. Inledningsvis undersöktes morfologin och storleksstabiliteten hos vesiklarna genom atomkraftsmikroskopi och dynamisk ljusspridning. Dessa studier visade på storleksheterogenitet och agglomereringstendenser hos vesiklarna. Jämförande studier av fysiologiska EVs avslöjade deras förhållandevis högre storleksstabilitet, medan RBC-producerade vesiklar uppvisade reversibla agglomerationer i omkring 50 % av fallen. För det andra utvecklades en experimentell analysmetod med tvåfärgs-avläsning av sammanfallande fluorescens-signaler (DC-CFB). Metoden användes sedan för att karakterisera och profilera molekylupptaget hos de bioteknologiskt framtagna nanovesiklarna. Därmed var det möjligt att hantera vesiklarnas ringa storlek (under diffraktionsgränsen), deras inneboende heterogenitet och närvaron av fria, icke-inkapslade molekyler. Den utvecklade metoden tillämpades därefter för att utforska upptaget i vesiklarna av relativt små nukleotider (dUTP) såväl som av större antikroppsmolekyl (Ab), motiverat utifrån en, QC 2024-01-08

A novel design of a polarization controller based on "etch-less" Si3N4-loaded thin film LiNbO3 is described. Broadband operation in the spectral range between 1.45 and 1.65 mu m is achieved by using a mode evolution TM/TE splitter/converter, two mode evolution 3-dB couplers, and two electro-optic phase shifters. Numerical simulations show that the on-chip insertion loss should not exceed 1 dB. A single TE-mode output can be adjusted by applying control voltages lower than 10 V for an arbitrary input polarization state.

Wavelength conversion processes such as spontaneous parametric down conversion (SPDC) and optical parametric amplification (OPA) are key elements in integrated quantum optics. On-chip integration of these function-alities would allow for increased performance and huge scaling opportunities. However, CMOS-compatible plat-forms such as silicon and silicon nitride (SiN) lack a $chi$(2) nonlinearity due to their inversion symmetry. This work provides a solution by heterogeneously integrating periodically poled lithium niobate (PPLN) onto SiN waveguides through micro-transfer printing (textmuTP) [1]. The textmuTP method is a scalable back-end process, allowing the fabrication of the photonic integrated circuit to remain CMOS-compatible., info:eu-repo/semantics/published

A high-speed modulator on silicon nitride is demonstrated using 2 mm-long micro-transfer printed lithium niobate coupons. This device has a 3-dB bandwidth ANDgt;50GHz, and an insertion loss of 3.3 dB that allowed us to transmit 70 Gb/s., info:eu-repo/semantics/published

Several established photonic platforms lack a nonzero Pockels and nonlinear coefficient. We developed a micro-transfer printing method to heterogeneously integrate thin-film lithium niobate and gallium phosphide with an experimentally shown transfer yield of near-unity., info:eu-repo/semantics/published

Thesis (Ph. D.)--University of Rochester. Department of Electrical and Computer Engineering, 2020., On-chip generation of optical frequency combs via the Kerr nonlinearity has attracted significant interest in recent years and the use of these devices for comb systems on a chip is being studied across a wide range of applications including spectroscopy, communication, ranging, frequency synthesis and optical clocks. The recent realization of stable mode locking of Kerr microcombs, wherein the comb lines are mutually phase locked to form a stable soliton pulse train in time, is crucial for these applications. The wide range of functions that are possible with lithium niobate (LN) waveguide devices, including phase and intensity modulation, second-harmonic generation and difference-frequency generation, make it attractive as a potential microcomb material. This thesis focuses on the generation of Kerr soliton combs in high-quality LN microresonators. This thesis starts with dispersion-engineering in LN microring resonators, whose group velocity dispersion (GVD) can be precisely controlled in the normal and anomalous dispersion regimes, while simultaneously exhibiting high optical Qs greater than one million. Both small anomalous dispersion and high Q are essential prerequisites for Kerr frequency comb generation. By employing such type of devices, broadband soliton microcombs are produced in the telecom-band. Direct frequency doubling as well as a self-frequency shift resulting from the Raman effect are observed in the meanwhile. The LN soliton mode locking process also self-starts and allows bi-directional switching of soliton states, effects that are shown to result from the LN photorefractive effect. Based on those unique properties, this thesis continues to present on-demand generation of perfect soliton crystals, where we are able to continuously tune the comb line spacing from 1 to 11 times of the resonator free spectra range. The further exploration of observed Raman and second harmonic effects are also demonstrated. Finally, in order to engineer GVD in over

The features of nanodomain growth during local switching in X-cut lithium niobate on insulator (LNOI) were comprehensively studied using the biased tip of a scanning probe microscope. The obtained results were discussed in terms of the kinetic approach. The revealed differences in domain growth in bulk LN and LNOI were attributed to the higher bulk conductivity of LNOI. The obtained influence of humidity on the shape and growth of isolated domains was attributed to the water meniscus. Analysis of the transition between the “forward growth” and “sideways growth” stages was performed by switching to the stripe electrode. A sand-glass-shaped domain was formed due to growth in the opposite direction after the domain touched the electrode. Stable periodical domain structures down to 300 nm were created and characterized in LNOI. Highly ordered comb-like domains of various alternating lengths, including four-and eight-fold increase periods, were produced by performing biased tip scanning along the Y axis. The obtained knowledge is important for the future development of nanodomain engineering methods in monocrystalline ferroelectric thin films on insulators. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

As silicon photonics has matured in the past decade, chip scale optics have become an enabling technology for data center, RF, high speed communication, and quantum optic devices, and the number of devices being deployed into the world has increased by orders of magnitudes. However, the limitations arising from inherent optical nonlinearities in the material and mechanisms of modulation are still problems. In the present work, we describe research done to address some of the limitations across two areas: 1) designing foundry silicon photonic resonant devices to operate at their limits of optical power and compact scalable that address wavelength selective communication needs, and 2) not-etched nor patterned thin-film lithium niobate on top of foundry silicon photonic device through hybrid integration in a scalable manner, to enable high speed (>100 GHz) and high extinction devices. The latter part of this thesis presents novel photonic circuits in which we leverage the recently developed hybrid-silicon thin-film lithium niobate platform to tune the spectral properties of quantum light generated in a monolithic chip with the hybrid material, presenting a scalable means of pushing beyond the limitations of conventional silicon photonics.

We study the influence of wave propagation direction on the SAW modes excitation and their characteristics in the SiO2/IDT/128°Y-cut LiNbO3 structures. The three-dimensional finite element method analysis reveals that the multilayer structure can support the Love wave, Rayleigh wave, Sezawa wave, 1st Love wave, and 2nd Rayleigh wave. Consistent with the measured result of the super-high frequency (2-10 GHz) SAW devices, the Love wave mode is coupled with the Rayleigh wave mode. Meanwhile, because of the effect of the electrode, symmetric and antisymmetric modes of the Rayleigh wave and Sezawa wave appear simultaneously. This work guides further optimization of the device at super-high frequency. © 2022 IEEE.

This paper presents a new method to improve the performance of SAW devices based on transferred lithium niobate thin films. Amorphous silicon replaces the single-crystal silicon to eliminate a conductive layer generated in the thin-film transfer processes. As a result, the electromechanical coupling of the surface-guided acoustic wave is maximized, and the substrate loss is reduced in the amorphous-silicon-based hybrid wafer. The fabricated resonator shows an extracted electromechanical coupling coefficient of 22% with over 60 dB impedance radio, which is 30 dB higher than the resonator with parasitic surface conductive effect. The fabricated delay lines show excellent propagation properties of the excited surface-guided acoustic wave with a minimum propagation loss of 18.1 dB/mm at 2.35 GHz, which further demonstrate the elimination of the conductive layer and outstanding acoustic energy confinement between lithium niobate and amorphous silicon. This work has shown the strong potential of the silicon-SAW platform for front-end signal processing. © 2022 IEEE.

A diffractive optical element based on a nonlinear-optical ferroelectric single crystal has been proposed, synthesized, and experimentally characterized. The element allows fast modulation of transverse modes of a Gaussian laser beam. © 2021, Institution of Russian Academy of Sciences. All rights reserved.

Ni-rich LiNi0.6Co0.2Mn0.2O2 (NCM) and LiNbO3-protected LiNi0.6Co0.2Mn0.2O2 (NCM) thin-film cathodes have been prepared by radio frequency (RF) magnetron sputtering. Electrochemical investigations show enhanced stability of LiNbO3-protected cathodes compared with bare LiNi0.6Co0.2Mn0.2O2. The interfacial interaction of LiNbO3 and LiNi0.6Co0.2Mn0.2O2 layers has been investigated by XPS depth profiling and demonstrated different cathode electrolyte interface (CEI) film formation processes at the electrodes. The results elaborate on the interaction between LiNbO3 and LiNi0.6Co0.2Mn0.2O2, emphasizing the role of the LiNbO3 layer in improving the cycling performance of Ni-rich cathodes.

The stability of solid-electrolyte interphase (SEI) surface films at Li-metal anodes is crucial for the safe and durable operation of lithium-metal batteries (LMBs). By combining Li-metal anodes with high-performance Ni-rich transition-metal oxide cathodes, LMBs can meet the goal of a high specific energy density of more than 500 Wh kg-1. However, Li-metal anodes suffer from serious problems, especially the nonuniform lithium deposition and uncontrollable SEI formation. In this work, Li-metal anodes were protected by thin-film LiNbO3 coatings. Full cells composed of protected Li-metal anodes and LiNi0.6Co0.2Mn0.2O2 cathodes were examined electrochemically and by physical characterization methods. Postmortem analyses of pristine and prolonged cycled Li-metal anodes were performed. The results revealed the formation of more stable SEI films at the protected Li-metal anodes in comparison to unprotected electrodes. Consequently, the LiNbO3 layers improved the cycle-life performance of Li-metal anodes in LMBs. Furthermore, X-ray photoelectron spectroscopy (XPS) analyses showed that the reduction of metallic ions stemming from the Ni-rich cathodes was also inhibited by the protective LiNbO3 layers, thereby further controlling the degradation of Li-metal anodes.

The ceramic and porcelain industry in the Arab Republic of Egypt annually produces a huge amount of by-product waste. Public health is threatened by the accumulated ceramic and porcelain dust and crumbs. In this study, five different ceramic and porcelain waste samples were recycled in glass form of xLiNbO3-(40-x)Waste and investigated with different LiNbO3 contents of x = 8, 16, 20, 24, 32 wt.% for useful nuclear radiation shielding applications. The amorphous structure of prepared samples is assured with XRD analyses. The radiation protection features of the prepared samples were investigated experimentally and compared with theoretical calculations for photon energies in the range of 81–2614 KeV. Moreover, optical parameters of waste glasses such as absorption coefficient, skin depth, and extinction coefficient have been calculated. The radiation protection factors showed that the Waste32 sample with 32 wt.% LiNbO3 is the best shield out of the fabricated Waste-x samples. The insertion of ceramic and porcelain wastes in the glass system reached 32 wt.%. © 2021 The Author(s).

Several applications in modern photonics require compact on-chip optical filters with a tailored spectral response. However, achieving subnanometric bandwidths and high extinction ratios is particularly challenging, especially in low-footprint device formats. Phase-shifted Bragg gratings implemented by the sidewall modulation of photonic nanowire waveguides are a good solution for on-chip narrowband operation with reasonable requirements in fabrication and scalability. In this work we report on their implementation and optimization in thin film lithium niobate, a photonic platform that affords reconfigurability by exploiting electrooptic effects. The phase-shifted Bragg grating filters have a footprint smaller than 1 mu m x 1 mm and operate at telecom wavelengths, featuring extinction ratios up to 25 dB. We demonstrate transmission bandwidths as narrow as 14.4 pm (Q = 1.1 x 10(5)) and 8.8 pm (Q = 1.76 x 10(5)) in critically coupled structures and multiwavelength Fabry-Perot configurations, respectively, in full agreement with theoretical predictions. Moreover, by taking advantage of the strong electro-optic effect in lithium niobate, in combination with the tight light confinement of nanophotonic wires and the ultranarrow spectral resonances of optimized grating structures, we demonstrate an electric tunability in peak wavelength and transmission of 25.1 pm/V and 2.1 dB/V, respectively, and a 10.5 dB contrast at CMOS voltages. The results pave the way for reconfigurable narrowband photonic filters with a small footprint and low consumption, to be exploited toward on-chip quantum and nonlinear optics, as well as optical sensing and microwave photonics., QC 20211117

A suspended thin-film lithium-niobate-on-insulator nano-waveguide (NanoLN) is designed, and tunable mid-infrared dispersivewave generation of high-efficiency and broadband is numerically studied on this designed platform. By hollowing out the silicon dioxide substrate between the NanoLN core and silicon wafer, the loss issue induced by mode leaking at mid-infrared region is eliminated. The second zero-dispersion wavelength of the suspended NanoLN is tailored to locate around 2 mu m wavelength, so that mode-locked fiber laser pump sources in this waveband can be conveniently leveraged to generate dispersive wave beyond 3 mu mwavelength. We show that dispersive wave at 3.16 mu m with high conversion efficiency up to 36.26% and bandwidth (at 10 dB level) of similar to 471 nm can be achieved at the pump pulse energy of 0.23 nJ. The central wavelength of the dispersive wave can be flexibly tuned up to 5 mu m with a maximum 10 dB bandwidth of similar to 2 mu m by lithographic control of the waveguide geometry, which is naturally at the expense of degraded conversion efficiency. Our results show the suspended NanoLN can provide a versatile chip-scale platform for cost-effective mid-infrared targetable, broadband, and coherent sources generation. Using fiber laser pump sources gives the advantages of compactness, free-maintenance, and long-term stability, which suit field applications., QC 20210401

The transient terahertz (THz) pulse with high peak field has become an important tool for matter manipulation, enabling many applications such as nonlinear spectroscopy, particle acceleration, and high harmonic generation. Among the widely used THz generation techniques, optical rectification in lithium niobate (LN) has emerged as a powerful method to achieve high fields at low THz frequencies, suitable to exploring novel nonlinear phenomena in condensed matter systems. In this review, we focus on introducing single- to few-cycle THz generation in LN, including the basic principles, techniques, latest developments, and current limitations. We will first discuss the phase matching requirements of LN, which leads to Cherenkov-like radiation, and the tilted pulse front (TPF) technique. Emphasis will be put on the TPF technique, which has been shown to improve THz generation efficiency, but still has many limitations. Different geometries used to produce continuous and discrete TPF will be systematically discussed. We summarize the advantages and limitations of current techniques and future trends., source:https://www.mdpi.com/2304-6732/8/6/183

The defining challenge of connecting NISQ quantum computers over large distances is efficient microwave to optical transduction. In this work, we demonstrate a new platform for piezo-optomechanical conversion by combining a crystalline silicon nanobeam photonic crystal cavity and a suspended thin-film lithium niobate acoustic resonator. The goal is to combine the excellent optomechanical properties of the silicon nanobeam cavity with coherent excitations in a piezoelectric resonator in order to achieve large effective coupling between the microwave excitation and the optical cavity. In order to fabricate this hybrid silicon-on-lithium niobate device, we explore a technique termed ‘slapping’ where a loosely connected suspended nanostructure is patterned such that a tapered optical fiber can be used to rip it away and place it in an arbitrary location on another chip. We report a single photon optomechanical coupling rate g_0 = 5.1 kHz and a single photon microwave to optical efficiency of η_{μ→o} = 6.1 × 10−6 at 25μW of input optical power in a device limited by a suboptimal optical interface., Casimir Research School

In this work, thin-film lithium niobate (LiNbO3) acoustic delay line (ADL) based oscillators are experimentally investigated for the first time for the application of single-mode oscillators and frequency comb generation. The design space for the ADL-based oscillator is first analyzed, illustrating that the key to low phase noise lies in high center frequency (fo), large delay (τ G), and low insertion loss (IL) of the delay. Therefore, two self-sustained oscillators employing low noise amplifiers (LNA) and a low IL, long delay (fo=157MHz, IL =2.9dB, τG= 200-440ns) SH0 mode ADLs are designed for a case study. The two SH0 ADL oscillators show measured phase noise of -109 dBc/Hz and -127 dBc/Hz at 10-kHz offset while consuming 16 mA and 48 mA supply currents, respectively. Although the carrier power of the proposed oscillator is lower than published state-of-the-art ADL oscillators, competitive phase noise performance is still attained thanks to the low IL. Finally, frequency comb generation is also demonstrated with the same delay line and a commercial RF feedback amplifier, showing a comb spacing of 3.4 MHz that matches the open-loop characterization., Accepted Author Manuscript, Dynamics of Micro and Nano Systems

Here, we propose an optimized Y -rotated cut of lithium niobate (LN) for multidirectional surface acoustic wave (SAW) propagation, simultaneously minimizing the anisotropic effects while maximizing the electromechanical properties of this cut of LN. The goal is to offer a piezoelectric material suitable for acoustofluidics applications that require greater flexibility in wave generation and propagation than the currently ubiquitous 128° Y -rotated X -propagating cut. The 128YX LN cut is known to most effectively generate Rayleigh SAW along the x -direction alone. Any SAW veering from this propagation direction is affected by beam steering and changes in resonance frequency and electromechanical coupling coefficients, consequently limiting the use of LN in various acoustofluidics applications, where more diverse configurations would be beneficial. The L2 -norm of these properties was evaluated under rotational transformation to produce a physical model with closed governing equations for 40-MHz surface wave propagation on the surface of a piezoelectric material. This was then utilized to obtain the surface wave velocity and coupling coefficient of the specific Y -cut LN with respect to the propagating direction. Next, the averaged coupling coefficients of various Y -cuts of LN in all propagating directions were calculated and integrated to simultaneously minimize anisotropy and maximize the electromechanical properties of the LN substrate. A 152° Y -rotated cut was found to be the optimal choice under these constraints, enabling multidirectional SAW propagation with greater coupling and lower variation in wave performance for SAW generated across the surface in any direction. Compared with the 128YX LN cut, this cut provides a 66.5% improvement in the in-plane isotropy and a 37.0% improvement in the average electromechanical coupling for in-plane SAW propagation. Experimental devices operating at the frequency of 40 MHz were designed, fabricated, and tested on the su

The domain switching by ion beam irradiation of single-domain Y-cut plates of congruent lithium niobate doped by 5 mol% MgO was studied. Dot irradiation resulted in the formation of wedge-like domains grown along Z- polar direction. The nonlinear dependences of the domain sizes on irradiation conditions were obtained. The model of domain growth on non-polar cut was proposed in frame of kinetic approach. The absence of the domain merging along Z- polar direction was attributed to the deceleration of the forward growth by electrostatic interaction of the positive charges at the charged domain walls and injected positive ions. © 2020, © 2020 Taylor & Francis Group, LLC.

This work presents the first demonstration of the first-order antisymmetric (A1) mode lateral overtone bulk acoustic resonators (LOBAR) in thin-film lithium niobate (mathrm{LiNbO}{3}). Thanks to the fast phase velocity, large coupling, and low loss of A1 in mathrm{LiNbO}{3}, equally spaced tones around 5 GHz are achieved using a large feature size of 500 nm. Electromechanical coupling (k-{2}) around 0.4 % and high Q over 1000 are observed in more than 20 tones, surpassing the reported overtone resonators at 5 GHz. Meanwhile, the highest Q of 2725, and the highest fQ product of 1.4cdot 10-{13} are measured at 5.16 GHz. Upon further optimizations, A1 LOBARs can facilitate novel 5G signal processing functions. © 2020 IEEE.

This work presents an improved design that exploits dispersion matching to suppress the lateral spurious modes in the thin-film lithium niobate first-order antisymmetric Lamb wave mode (A1) resonators. The dispersion matching in this work is achieved by micro-machining the lithium niobate thin film to balance the electrical and mechanical loading of electrodes. The fabricated devices based on the proposed method exhibit spurious-free responses with a maximum Q{3dB} of 692 and k{t}{}-{2} of 28%. The demonstrated method herein could overcome a significant hurdle that is currently impeding the commercialization of A1 devices. © 2020 IEEE.

This paper presents an 8.6 GHz oscillator utilizing a third antisymmetric overtone ( A3) in a lithium niobate (LiNbO 3 ) resonator for 5G communications. The oscillator consists of an acoustic resonator in a closed loop with cascaded RF tuned amplifiers (TAs) built on TSMC RF GP 65 nm CMOS. The TAs bandpass response, set by on-chip inductors, satisfies the Bark-hausen's oscillation conditions for A3 while suppressing the fundamental and higher-order resonances. The oscillator achieves a measured phase noise of -56 and -113 dBc/Hz at 1 kHz and 100 kHz offsets from an 8.6 GHz output while consuming 10.2 mW of dc power. The oscillator also attains a figure-of-merit of 201.6 dB at 100 kHz offset, surpassing the state-of-the-art (SoA) EM and RF-MEMS oscillators.

We present the first group of acoustic delay lines (ADLs) at 5 GHz using the first-order antisymmetric (A1) mode in Z-cut lithium niobate thin films. The demonstrated ADLs significantly surpass the operation frequencies of the prior art with similar feature sizes because of their simultaneously fast phase velocity, large coupling coefficient, and low loss. In this article, the propagation characteristics of the A1 mode in lithium niobate are analytically modeled and validated with finite element analysis. The design space of A1 ADLs is then investigated, including both the fundamental design parameters and those introduced from the practical implementation. The implemented ADLs at 5 GHz show a minimum insertion loss of 7.9 dB, an average insertion loss (IL) of 9.1 dB, and a fractional bandwidth around 4%, with group delays ranging between 15 and 109 ns and the center frequencies between 4.5 and 5.25 GHz. The propagation characteristics of A1 mode acoustic waves have also been extracted for the first time. The A1 ADL platform can potentially enable wideband high-frequency passive signal processing functions for future 5G applications in the sub-6-GHz spectrum bands. © 1963-2012 IEEE.

IIn this work, we present first-order antisymmetric (A1) mode resonators in 128° Y-cut lithium niobate (LiNbO 3 ) thin films with electromechanical coupling coefficients (k 2 ) as large as 46.4%, exceeding the state-of-the-art. The achievable k 2 of A1 in LiNbO 3 substrates of different orientations is first explored, showing X-axis direction in 128° Y-cut LiNbO 3 among the optimal combinations. Subsequently, A1 resonators with spurious mode mitigation are designed and fabricated. In addition to the large k 2 , the implemented devices show a maximum quality factor (Q) of 598 at 3.2 GHz. Upon further optimization, the reported platform can potentially deliver a wideband acoustic-only filtering solution in 5G New Radio.

Магістерська дисертація містить основну частину на 83 аркушах, кількість ілюстрацій 33, таблиць 28, джерел 24. Об’єктом дослідження є процес радіочастотної ідентифікації об’єктів з використанням поверхневих акустисних хвиль. Предмет дослідження це мітки пристроїв радіочастотної ідентифікації на основі поверхневих акустичних хвиль. Метою дипломної роботи є ознайомлення і вивчення механізмів радіочастотної ідентифікації на ПАХ. Методом дослідження є теоретичний аналіз фізичних принципів дії, конструктивних особливостей радіочастотної ідентифікаційної мітки на ПАХ. Розглянуті основні етапи розробки РЧІД мітки на ПАХ. Проаналізовані основні вимоги до матеріалів підкладок акустичного каналу пристроїв на ПАХ. Зроблений підбір матеріалу підкладки акустичного каналу. Розраховані характеристики і розміри основних конструктивних елементів мітки на ПАХ. Результати проекту можуть бути використані для підкреслення актуальності проектування та використання із запропонованих можливиїх сфер застосування пристроїв РЧІД на ПАХ., Thesis contains the bulk of the 83 pages, 33 illustrations, 28 table, sources of information 24. The object of research is the process of radio frequency identification (RFID) of objects with using surface acoustic waves (SAW). The subject of the study is the labels of radio frequency identification (RFID) devices based on surface acoustic waves (SAW). The aim of the thesis is to review and study the technology of RFID surface acoustic wave. The method of research is theoretical analysis of the physical principles of action, structural features radio frequency identification SAW tags. The basic stages of RFID SAW tags. The basic requirements for substrate materials acoustic channel SAW devices. Made selection of acoustic material lining the channel. Calculated characteristics and size of the main structural elements of SAW tags. Project results can be used to emphasize the importance of design and use of the proposed possible applications RFID SAW devices.

Fiber-coupled superconducting nanowire single photon detectors are a ubiquitous tool for quantum optics experiments as they offer near unity detection efficiency over a broad wavelength range, low dark count rate, excellent time resolution and high saturation rate. Nevertheless, advancing quantum optics experiments and applications beyond the few-photon limit requires large scale integrated systems of quantum sources and detectors. In recent years there has been a tremendous progress with integrating single photon detectors with a variety of photonic platforms. This includes attempts on ion-diffused waveguides in LiNbO3, a non-linear and electro-optic material with widespread use for signal processing, frequency conversion, and quantum optics devices. However the realization of superconducting detectors on single mode waveguides remains elusive. Here we present an NbTiN superconducting single photon detector integrated directly on a LiNbO3 single mode nanophotonic waveguide at telecom wavelength, with a high critical current density and a dark count rate of 3 mHz at 99% of its critical current., QC 20190523

To understand and predict phenomena in solid materials, we often look at how the lattice structure brings about such an effect. Our lab analyzes the extended x-ray absorption fine structure (EXAFS) to closely study the physical configuration of atoms in a lattice. I will talk about the interesting local structure of the following compounds: Organic lead-halide perovskites MAPbI3 andMAPbBr3, ytterbium doped calcium fluorite (CaF2:Yb), and lithium niobate doped with Zn,Er,In, and Hf.Organic perovskites have been a material of high interest for harvesting light. In order to improve crystallization of solution based methylammonium lead iodide (MAPbI3), we aim to maximize lead-iodide coordination via an excess of iodide precursors: methylammonium iodide (MAI) and hydrodic acid (HI). We find that a surplus of HI results in higher order and coordination for the nearest Pb–I atomic shell (six iodine neighbors). In another study, we look into the disorder and vibrational properties of MAPbBr3 in different structural phases. This dissertation includes a temperature dependent study on the local structure of MAPbBr3, and a rigorous quantifying of the anharmonicity parameter, C3, that represents dynamic disorder. C3 increases nonlinearly with temperature and results in an asymmetric pair distribution for the nearest Pb–Br shell.Calcium fluorite doped with ytterbium is a doped simple FCC crystal with a down-shifted anomalous luminescence. A long lived excited state decays with a yellow-green emission and can be induced with UV exposure. With two consistent methods quantifying amount of Yb in the 2+ and 3+ state, we present compelling evidence that the impurity trapped exciton model does not explain this system. Further, we can elucidate the various metastable states of this system and their relation to strange observations.Finally, lithium niobate has piqued interest in frequency conversion device engineering as a non-linear optical material. There lacks a general model for how t

The features of the domain patterning in thin lithium niobate crystals were studied. It was shown that decrease in crystal plate thickness led to domain size increase due to limitation of forward growth. The domain size weakly depended on electron energy due to equality of screening charge value at the same doses and various accelerating voltages. The weak dependence of domain sizes on pattern period was attributed to absence of electrostatic interaction of domain walls. The possibility of creation of the through periodical domain structures with the vertical domain walls and period down to 2 μm in thin crystal was demonstrated. © 2019, © 2019 Taylor & Francis Group, LLC.

Light-induced phenomena in ferroelectric materials have been exploited for decades for optoelectronic applications. Homogeneous illumination of a non-centrosymmetric ferroelectric material creates anomalously high voltages exceeding a value which is usually limited by its band gap. This phenomenon is called the bulk-photovoltaic effect (BPVE). Lithium niobate is a prototypical material for BPVE. The only limiting factor in lithium niobate is its low photo-current values, which can be improved by doping the crystal with donor metals. This study focuses primarily on light induced processes in mono-domain lithium niobate single crystals doped with transition metal ions, particularly the influence of stress on the BPVE. The effect of stress on BPVE is termed the piezo-photovoltaic effect (PPVE). This thesis report is framed to systemically introduce topics which cause, influence and aid in understanding the PPVE. Topics such as the symmetry in crystals, their physical properties, the intrinsic bulk photovoltaic effect (BPVE) are introduced and the structure, defects, light-induced charge transport in donor doped lithium niobate and the reason behind the appearance of BPVE are discussed in this report. The techniques and experimental arrangements used in this work are detailed in this thesis. A direct evidence of BPVE and the influence of stress is shown in the results. Transition metal doped lithium niobate crystals are oriented via x-ray diffraction (XRD) and a basic chemical characterization is undertaken using secondary ion mass spectrometry (SIMS) to identify dopant elements. Absorption spectroscopy in the UV/VIS/NIR range revealed windows in the spectra indicating photo-excitation of the donor doped ions. The absorption lines show that a shift in the fundamental band-edge occurs in lithium niobate for different dopant elements. Electron paramagnetic resonance (EPR) spectrometry is performed on the samples to confirm the location of the dopant ion in the crystal mat

The effects of domain wall shape instabilities and the formation of nanodomains in front of moving walls obtained in various uniaxial ferroelectrics are discussed. Special attention is paid to the formation of self-assembled nanoscale and dendrite domain structures under highly non-equilibrium switching conditions. All obtained results are considered in the framework of the unified kinetic approach to domain structure evolution based on the analogy with first-order phase transformation. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’. © 2018 The Author(s) Published by the Royal Society. All rights reserved.

Polarization switching in ferroelectric materials underpins a multitude of applications ranging from nonvolatile memories to data storage to ferroelectric lithography. While traditionally considered to be a functionality of the material only, basic theoretical considerations suggest that switching is expected to be intrinsically linked to changes in the electrochemical state of the surface. Hence, the properties and dynamics of the screening charges can affect or control the switching dynamics. Despite being recognized for over 50 years, analysis of these phenomena remained largely speculative. Here, we explore polarization switching on the prototypical LiNbO3 surface using the combination of contact mode Kelvin probe force microscopy and chemical imaging by time-of-flight mass-spectrometry and demonstrate pronounced chemical differences between the domains. These studies provide a consistent explanation to the anomalous polarization and surface charge behavior observed in LiNbO3 and point to new opportunities in chemical control of polarization dynamics in thin films and crystals via control of surface chemistry, complementing traditional routes via bulk doping, and substrate-induced strain and tilt systems., QC 20181003

This work demonstrates a passive low-insertion-loss (IL)RF filter with periodic passbands and capable of sparsifying the spectrum from 238 to 526 MHz for sparse Fourier transform (SFT)based spectrum sensing. The demonstrated periodic filter employs LiNbO 3 lateral overtone bulk acoustic resonators (LOBARs)with high-quality factors (Qs), large electromechanical coupling (k t 2 ), and multiple equally spaced resonances in a ladder topology. The fabricated LOBARs show k t 2 larger than 1.5% and figure of merits (k 2 Q) more than 30 for over 10 tones simultaneously and are both among the highest demonstrated in overmoded resonators. The multi-band filter centered at 370 MHz have then been obtained with a passband span of 291 MHz, a spectral spacing of 22 MHz, an IL of 2 dB, FBWs around 0.6%, and a sparsification ratio between 7 and 15. An out-of-band rejection around 25 dB has also been achieved for more than 14 bands. The great performance demonstrated by the RF filter with 14 useable periodic passbands will serve to enable future sparse Fourier transform-based spectrum sensing. © 2018 IEEE.

This work demonstrates the first 4-port radio frequency circulator based on switched low-loss acoustic delay lines. The 4-port circulator is built upon a recently reported frequency-independent, programmable, and non-reciprocal framework based on switched delay lines. Large delays provided by the in-house fabricated, low-loss, and wide-band lithium niobate (LiNbO 3 )SH0 mode acoustic delay lines are leveraged to produce high performance and reduce the modulation effort simultaneously for enabling non-reciprocity. The implemented 4-port circulator has been demonstrated with an 18.8 dB non-recip-rocal contrast between the insertion loss (IL = 6.6 dB)and isolation (25.4 dB)over a fractional bandwidth of 8.8% at a center frequency 155 MHz, using a record low switching frequency of 877.19 kHz. The circulator also shows 25.9 dB suppression for the intra-modulated tones. Upon further development, such a system can potentially lead to wide-band, low-loss chip-scale nonreciprocal RF systems with unprecedented programmability. © 2018 IEEE.

This paper demonstrates low-loss acoustic delay lines based on the fundamental symmetrical (S0)mode in lithium niobate thin films for the first time. The demonstrated devices harness the high electromechanical coupling, low loss, and fast phase velocity of the symmetrical mode in the X-cut lithium niobate to achieve an insertion loss as low as 1 dB at 300 MHz. The designs adopt single-phase unidirectional transducers to achieve low insertion loss and flat group delay responses simultaneously. Devices with different key parameters are implemented with fractional bandwidths ranging from 4.1% to 12.8% and delays ranging from 32 ns to 195 ns. With the demonstrated low loss and wide bandwidths, these devices can unlock new possibilites for low-power RF signal processing in the acoustic domain. © 2018 IEEE.

Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), School of Environment and Sc, Science, Environment, Engineering and Technology, Herewithin we present multiplexed integrated photonics as a realisable route to large-scale quantum technologies. Quantum photonics is one many platforms for experimental demonstrations of quantum information science. The technological advantages afforded by the combination of integrated photonic circuits with multiplexing techniques can enable performance enhancements to make photonics a leading infrastructure for implementation of real-world quantum information systems. For this purpose, we create integrated circuits to solve technical challenges in the fields of quantum cryptography, discrete variable and continuous variable quantum computation. These circuits were fabricated in a facility developed at Griffith University, Centre for Quantum Dynamics, for the production of annealed and reverse proton exchange waveguides in congruent lithium niobate and have found applications across the fields of quantum optics and cryptography. We develop and demonstrate the first integrated many-mode active optical demultiplexing of single photons from a solid-state source. This scheme enables the production of a multiphoton Fock state across multiple spatial modes from a single high brightness solid-state source with temporal indistinguishability. This work addressed a major hurdle in the development of photonic quantum computers, namely generation of a large number of indistinguishable single photons on demand. To perform the demultiplexing of single photons we develop two key technologies; a high-speed 1:4 integrated photonic switch and a many channel arbitrary pulse sequence generator. Cryptography as a field is increasingly reliant on quantum random number generators for added security. With increased demand comes a requirement for higher bitrate random number generators, and as such we demonstrate multiplexing of a random number generation scheme based on measurements of quantum vacuum fluctuations. Furthermore, we show an increased level of security at high bitrates by i

Im Rahmen dieser Dissertation wird die Kopplung von einer ultraschnellen optischen Interband-Anregung und der Erzeugung von akustischen Phononen im ferroelektrischen Prototyp-Material Lithiumniobat (LiNbO3) studiert. Unter Verwendung der Anrege-Abfrage-Technik wird LiNbO3 mit ultrakurzen optischen Lichtimpulsen angeregt und die Antwort des LiNbO3-Kristallgitters mit harten Femtosekunden-Röntgenimpulsen abgefragt. Zur Erzeugung der ultrakurzen Röntgenimpulse (100 fs) wird eine kompakte, lasergetriebene Femtosekunden-Röntgenquelle mit einer 1 kHz Repetitionsrate genutzt. Die Stärke und die zeitliche Evolution der beobachteten integralen Röntgen-Reflektivität ausgewählter Bragg-Reflexionen ist charakteristisch für die Propagation von starken akustischen Deformationswellen in einem homogen angeregten Einkristall. Überraschenderweise weisen sowohl die Polarisation als auch die Propagationsgeschwindigkeit der aktivierten Phononmoden eine hohe Anisotropie in Abhängigkeit der Ausrichtung der ferroelektrischen Achse relativ zur Polarisation der optischen Anrege-Impulse auf. Die bekannten Kopplungsmechanismen, wie das elektronische Deformationspotential oder die anharmonische Phonon-Phonon-Wechselwirkung, sind zur Erklärung der akustischen Deformationswellen mit der beobachteten Amplitude und der hohen Anisotropie ungeeignet. Stattdessen konnte gezeigt werden, dass die impulsive mechanische Spannung über den piezoelektrischen Effekt erzeugt wird. Die dafür notwendige makroskopische elektrische Polarisation resultiert aus einem photoinduzierten Verschiebestrom, welcher die Folge der optischen Interband-Anregung mittels Zwei-Photonen-Absorption ist. Diese optisch-elektrisch-mechanische Kopplung zwischen dem nichtlinearen Leitfähigkeitstensor fünfter Ordnung, dem piezoelektrischen Tensor und den relevanten Phononmoden ermöglicht eine vollkommene Beschreibung der experimentellen Beobachtungen., The coupling between an ultrafast optical interband excitation and the generation of acoustic phonons in the ferroelectric prototype material lithium niobate (LiNbO3) is studied. Employing the pump-probe technique, LiNbO3 is excited optically with ultrashort light pulses while the impact on the crystal lattice is probed by femtosecond hard x-ray pulses. A compact, laser-driven femtosecond x-ray source with a 1-kHz repetition rate provides 100-fs pulses for time-resolved experiments. With this experimental arrangement, the response of the LiNbO3 crystal lattice to a nonlinear optical excitation can be investigated. The strength and temporal evolution of the observed integrated x-ray reflectivity of selected Bragg reflections are consistent with the propagation of a strong acoustic strain wave in a homogeneously excited single crystal. Surprisingly, both the polarization of the activated phonon modes and the propagation velocity show a high anisotropy as a function of the ferroelectric axis orientation relative to the polarization of the optical excitation pulses. The previously known coupling mechanisms, such as the electronic deformation potential or the anharmonic phonon-phonon interaction, are insufficient to explain the observed deformation amplitude and high anisotropy of the acoustic strain waves. Instead, it is shown that the impulsive mechanical stress is generated via the piezoelectric effect. The required macroscopic electrical polarization is a result of a photoinduced shift current, which in turn is generated by the optical interband excitation via two-photon absorption. This optical-electrical-mechanical coupling between the fifth-order nonlinear conductivity tensor, the piezoelectric tensor, and the relevant phonon modes fully describe the experimental observations.

Y128- and Y36-cut single-crystalline lithium niobate (LN) thin films are fabricated by the crystal-ion-slicing (CIS) technique onto LN substrates. The conditions for the successful exfoliation of submicron-thick LN thin films are independent of the wafer orientation used in the present work. Wafer bonding using benzocyclobutene (BCB) is adopted to transfer LN thin films onto substrates, instead of the generally used hydrophilic bonding, which does not need a strict surface polishing process before the bonding. A noncontact polishing method involving low-energy Ar+ irradiation is adopted to treat the sliced LN thin films. The atomic force microscopy result shows that the surface roughness of the LN thin film is reduced from 10.6 to 6.4nm.

QC 20180110, vr-het

The first lithium niobate phononic crystals (PnCs) exhibiting band gaps for SH0 modes waves have been designed and demonstrated on X-cut thin films. Transmission properties of PnCs have been experimentally studied in phononic delay lines consisting of wideband input and output transducers separated by PnCs. An equivalent circuit model that incorporates PnCs acoustic scattering matrix and the conventional Mason's model has been constructed to accurately predict the experimental results. The measured devices show 20 dB attenuation for the SH0 mode in the stop-bands with less than 2 dB loss in the pass-bands. © 2017 IEEE.

This work presents the first demonstration of a frequency correlator based on shear horizontal waves in a suspended Lithium Niobate thin film. The device consists of symmetrically arranged input and output ports, each with five sections of transducers for five transmission bands over a wide frequency range from 154 to 297 MHz. The high electromechanical coupling of Lithium Niobate provides a fractional bandwidth over 60%, outperforming the state of the art surface acoustic wave correlators with a comparable insertion loss. The correlation has been verified with time-domain measurements, showing a voltage amplification factor of 2 for a correlated input, with respect to its time reversal. © 2017 IEEE.