Special Issue "Recent Progress in Lithium Niobate"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (31 March 2020).

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A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Robert A. Jackson
E-Mail Website
Guest Editor
School of Chemical and Physical Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK
Interests: computer modelling; interatomic potentials; optical materials; defects and dopants
Dr. Zsuzsanna Szaller
E-Mail Website
Guest Editor
Wigner Research Centre for Physics, Budapest, Hungary
Interests: single crystal growth; high-temperature top-seeded solution growth; non-faceted growth; stoichiometric LiNbO3; optical damage resistant dopants

Special Issue Information

Dear Colleagues,

This planned special issue of Crystals is the third issue devoted to LiNbO3 (the previous two being on ‘Lithium Niobate Crystals’ and ‘Thin Films and Nanocrystals’).

LiNbO3 is an all-star material from both the scientific and technological viewpoints and the subject of a great number of publications since its first preparation in 1937. Due to its excellent electro/acousto-optical properties, LiNbO3 has been widely used in optoelectronic devices for decades, ranging from optical fibre communications to wireless and micromechanical systems. Among the latest applications are modulators and filters with lasers on a single LiNbO3 wafer, especially promising in integrated optics. Recently, high quality low optical loss source material for waveguides such as lithium niobate on insulator (LNOI) is playing an important role in photonic integrated circuits. LiNbO3 provides powerful optical components in high-energy laser applications, in terahertz technology and is also the subject of lead-free piezoceramics and nanophotonics.

The different applications require different forms of LiNbO3 such as bulk, thin film, nanocrystal and composite. In this Special Issue studies are welcomed dealing with different preparation techniques of different forms of LiNbO3, theoretical and experimental investigations of their structure and research on specific developments and novel applications.

Dr. Robert A. Jackson
Dr. Zsuzsanna Szaller
Guest Editors

Manuscript Submission Information

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Keywords

  • Crystal growth
  • Crystal defects
  • Computer modelling
  • Nanocrystals and nanopowders
  • Thin films
  • Composites
  • Lithium niobate waveguides
  • Integrated optics
  • Nonlinear optics
  • Photonics
  • Photovoltaics
  • THz-wave generation

Published Papers (10 papers)

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Editorial

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Editorial
Recent Progress in Lithium Niobate
Crystals 2020, 10(9), 780; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10090780 - 03 Sep 2020
Cited by 2 | Viewed by 634
Abstract
This special issue features eight papers which cover the recent developments in research on lithium niobate. Papers are divided into three groups based on their topic. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)

Research

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Article
Tunable Non-Volatile Memory by Conductive Ferroelectric Domain Walls in Lithium Niobate Thin Films
Crystals 2020, 10(9), 804; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10090804 - 11 Sep 2020
Cited by 6 | Viewed by 1015
Abstract
Ferroelectric domain wall conductance is a rapidly growing field. Thin-film lithium niobate, as in lithium niobate on insulators (LNOI), appears to be an ideal template, which is tuned by the inclination of the domain wall. Thus, the precise tuning of domain wall inclination [...] Read more.
Ferroelectric domain wall conductance is a rapidly growing field. Thin-film lithium niobate, as in lithium niobate on insulators (LNOI), appears to be an ideal template, which is tuned by the inclination of the domain wall. Thus, the precise tuning of domain wall inclination with the applied voltage can be used in non-volatile memories, which store more than binary information. In this study, we present the realization of this concept for non-volatile memories. We obtain remarkably stable set voltages by the ferroelectric nature of the device as well as a very large increase in the conduction, by at least five orders of magnitude at room temperature. Furthermore, the device conductance can be reproducibly tuned over at least two orders of magnitude. The observed domain wall (DW) conductance tunability by the applied voltage can be correlated with phase-field simulated DW inclination evolution upon poling. Furthermore, evidence for polaron-based conduction is given. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
Computer Simulation of the Incorporation of V2+, V3+, V4+, V5+ and Mo3+, Mo4+, Mo5+, Mo6+ Dopants in LiNbO3
Crystals 2020, 10(6), 457; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10060457 - 01 Jun 2020
Cited by 4 | Viewed by 1038
Abstract
The doping of LiNbO3 with V2+, V3+, V4+ and V5+ as well as Mo3+, Mo4+, Mo5+ and Mo6+ ions is of interest in enhancing its photorefractive properties. In this paper, [...] Read more.
The doping of LiNbO3 with V2+, V3+, V4+ and V5+ as well as Mo3+, Mo4+, Mo5+ and Mo6+ ions is of interest in enhancing its photorefractive properties. In this paper, possible incorporation mechanisms for these ions in LiNbO3 are modelled, using a new set of interaction potentials fitted to the oxides VO, V2O3, VO2, V2O5 and to LiMoO2, Li2MoO3, LiMoO3, Li2MoO4. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
Improvement on Thermal Stability of Nano-Domains in Lithium Niobate Thin Films
Crystals 2020, 10(2), 74; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10020074 - 30 Jan 2020
Cited by 4 | Viewed by 1050
Abstract
We present a simple and effective way to improve the thermal stability of nano-domains written with an atomic force microscope (AFM)-tip voltage in a lithium niobate film on insulator (LNOI). We show that nano-domains in LNOI (whether in the form of stripe domains [...] Read more.
We present a simple and effective way to improve the thermal stability of nano-domains written with an atomic force microscope (AFM)-tip voltage in a lithium niobate film on insulator (LNOI). We show that nano-domains in LNOI (whether in the form of stripe domains or dot domains) degraded, or even disappeared, after a post-poling thermal annealing treatment at a temperature on the order of ∼100 C. We experimentally confirmed that the thermal stability of nano-domains in LNOI is greatly improved if a pre-heat treatment is carried out for LNOI before the nano-domains are written. This thermal stability improvement of nano-domains is mainly attributed to the generation of a compensating space charge field parallel to the spontaneous polarization of written nano-domains during the pre-heat treatment process. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
High Homogeneity of Magnesium Doped LiNbO3 Crystals Grown by Bridgman Method
Crystals 2020, 10(2), 71; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10020071 - 29 Jan 2020
Cited by 4 | Viewed by 927
Abstract
A series of LiNbO3 crystals doped with various MgO concentrations (0, 3%, and 5 mol%) was simultaneously grown in one furnace by the modified vertical Bridgman method. The wet chemistry method was used to prepare the polycrystalline powders, and the growth conditions [...] Read more.
A series of LiNbO3 crystals doped with various MgO concentrations (0, 3%, and 5 mol%) was simultaneously grown in one furnace by the modified vertical Bridgman method. The wet chemistry method was used to prepare the polycrystalline powders, and the growth conditions were optimized. The full width at half maximum of high-resolution X-ray rocking curves for (001) reflection of 5 mol% Mg doped lithium niobate (LN) crystal was about 8″, which meant it possessed high crystalline quality. The OH absorption spectra shifted to 3534.7 cm−1, and the UV absorption edge violet shift indicated that 5 mol% MgO successfully doped in LN and exceeded the threshold. The extraordinary refractive index gradient of 5 mol% Mg doped LN crystal was as small as 2.5 × 10−5/cm, which exhibited high optical homogeneity. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
Design and Optimization of Proton Exchanged Integrated Electro-Optic Modulators in X-Cut Lithium Niobate Thin Film
Crystals 2019, 9(11), 549; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9110549 - 24 Oct 2019
Cited by 5 | Viewed by 1171
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
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
Crystals 2019, 9(9), 459; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9090459 - 02 Sep 2019
Cited by 7 | Viewed by 1236
Abstract
We studied photonic electric-field sensors using a 1 × 2 YBB-MZI modulator composed of two complementary outputs and a 3 dB directional coupler based on the electro-optic effect and titanium diffused lithium–niobate optical waveguides. The measured DC switching voltage and extinction ratio at [...] Read more.
We studied photonic electric-field sensors using a 1 × 2 YBB-MZI modulator composed of two complementary outputs and a 3 dB directional coupler based on the electro-optic effect and titanium diffused 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 fields 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-field strength within the range of 0.29 V/m to 29.8 V/m. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
Determination of the Chemical Composition of Lithium Niobate Powders
Crystals 2019, 9(7), 340; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9070340 - 03 Jul 2019
Cited by 6 | Viewed by 2017
Abstract
Existent methods for determining the composition of lithium niobate single crystals are mainly based on their variations due to changes in their electronic structure, which accounts for the fact that most of these methods rely on experimental techniques using light as the probe. [...] Read more.
Existent methods for determining the composition of lithium niobate single crystals are mainly based on their variations due to changes in their electronic structure, which accounts for the fact that most of these methods rely on experimental techniques using light as the probe. Nevertheless, these methods used for single crystals fail in accurately predicting the chemical composition of lithium niobate powders due to strong scattering effects and randomness. In this work, an innovative method for determining the chemical composition of lithium niobate powders, based mainly on the probing of secondary thermodynamic phases by X-ray diffraction analysis and structure refinement, is employed. Its validation is supported by the characterization of several samples synthesized by the standard and inexpensive method of mechanosynthesis. Furthermore, new linear equations are proposed to accurately describe and determine the chemical composition of this type of powdered material. The composition can now be determined by using any of four standard characterization techniques: X-Ray Diffraction (XRD), Raman Spectroscopy (RS), UV-vis Diffuse Reflectance (DR), and Differential Thermal Analysis (DTA). In the case of the existence of a previous equivalent description for single crystals, a brief analysis of the literature is made. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
Mechanochemical Reactions of Lithium Niobate Induced by High-Energy Ball-Milling
Crystals 2019, 9(7), 334; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9070334 - 28 Jun 2019
Cited by 11 | Viewed by 1267
Abstract
Lithium niobate (LiNbO3, LN) nanocrystals were prepared by ball-milling of the crucible residue of a Czochralski grown congruent single crystal, using a Spex 8000 Mixer Mill with different types of vials (stainless steel, alumina, tungsten carbide) and various milling parameters. Dynamic [...] Read more.
Lithium niobate (LiNbO3, LN) nanocrystals were prepared by ball-milling of the crucible residue of a Czochralski grown congruent single crystal, using a Spex 8000 Mixer Mill with different types of vials (stainless steel, alumina, tungsten carbide) and various milling parameters. Dynamic light scattering and powder X-ray diffraction were used to determine the achieved particle and grain sizes, respectively. Possible contamination from the vials was checked by energy-dispersive X-ray spectroscopy measurements. Milling resulted in sample darkening due to mechanochemical reduction of Nb (V) via polaron and bipolaron formation, oxygen release and Li2O segregation, while subsequent oxidizing heat-treatments recovered the white color with the evaporation of Li2O and crystallization of a LiNb3O8 phase instead. The phase transformations occurring during both the grinding and the post-grinding heat treatments were studied by Raman spectroscopy, X-ray diffraction and optical reflection measurement, while the Li2O content of the as-ground samples was quantitatively measured by coulometric titration. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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Article
The Photorefractive Response of Zn and Mo Codoped LiNbO3 in the Visible Region
Crystals 2019, 9(5), 228; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst9050228 - 28 Apr 2019
Cited by 5 | Viewed by 1104
Abstract
We mainly investigated the effect of the valence state of photorefractive resistant elements on the photorefractive properties of codoped crystals, taking the Zn and Mo codoped LiNbO3 (LN:Mo,Zn) crystal as an example. Especially, the response time and photorefractive sensitivity of 7.2 mol% [...] Read more.
We mainly investigated the effect of the valence state of photorefractive resistant elements on the photorefractive properties of codoped crystals, taking the Zn and Mo codoped LiNbO3 (LN:Mo,Zn) crystal as an example. Especially, the response time and photorefractive sensitivity of 7.2 mol% Zn and 0.5 mol% Mo codoped with LiNbO3 (LN:Mo,Zn7.2) crystal are 0.65 s and 4.35 cm/J at 442 nm, respectively. The photorefractive properties of the LN:Mo,Zn crystal are similar to the Mg and Mo codoped LiNbO3 crystal, which are better than the Zr and Mo codoped LiNbO3 crystal. The results show that the valence state of photorefractive resistant ions is an important factor for the photorefractive properties of codoped crystals and that the LN:Mo,Zn7.2 crystal is another potential material with fast response to holographic storage. Full article
(This article belongs to the Special Issue Recent Progress in Lithium Niobate)
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