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This work shows a detailed study of the synthesis, structural characterization, electrical, thermal, and mechanical luminescent behavior of one-dimensional coordination polymer formed by a Cu(I)-I double chain, using 2-amino-4 chloropyrimidine as ligand. The asymmetric structure of double chain type [Cu(L)I]n, (L= 2-amino-4-chloropyrimidine (aCLpym)) with Cu-Cu distances shorter than the sum of the van der Waals radii of two copper atoms, and the substantial flexibility of this structure are crucial to understanding its optoelectronic behavior. The electrical conductivity values at 295 K are in agreement with a possible semiconductor behavior. Additionally, the luminescence properties of this coordination polymer (CP) are characterized at ambient conditions (ambient pressure (AP) and 295 K) by a non-symmetric High Energy (HE) band centered at 465 nm, tentatively assigned to a mixed 3(I+M)LCT. The intensity of the emission increase lowering the temperature. A structural contraction can explain this behaviour, clearly observed when solving the structures employing single-crystal X-ray diffraction of the compound at 296 K and 110 K. A strong mechanochromic behavior was observed when hydrostatic pressure is applied, with the appearance of an additional Low Energy (LE) band around 650 nm, which for this kind of CuI CPs is typically associated with transitions in the CuI cluster-core, involving 3IMCT and clustered centered 3d10→3d94s1 (3MCC) states. This latter because of the shortening with the pressure of the Cu-Cu distances below the Van der Waals limit. Moreover, the study of the mechanochromic behavior versus pressure exerted by grinding shows a decrease in the intensity of the emission due to the increase in the number of defects and decrease in the particle size

Two coordination polymers with formulas [CuI(dapym)]n and [Cu2I2(dapym)]n (dapym = 2,4-diaminopyrimidine) have been synthesized in water at room temperature. According to the stoichiometry used, mono (1D) and the two-dimensional (2D) structures can be obtained. Both are made up of Cu2I2 double chains. Their high insolubility in the reaction medium also makes it possible to obtain them on a nanometric scale. Their structural flexibility and short Cu-Cu distances provoke interesting optoelectronic properties and respond to physical stimuli such as pressure and temperature, making them interesting for sensor applications. The experimental and theoretical studies allow us to propose different emission mechanisms with different behaviors despite containing the same organic ligand. These behaviors are attributed to their structural differences. The emission spectra versus pressure and temperature suggest competencies between different transitions, founding critical Cu2I2 environments, i.e., symmetric in the 1D compound and asymmetric for the 2D one. The intensity in the 2D compound's emission increases with decreasing temperature, and this behavior can be rationalized with a structural constriction that decreases the Cu-Cu and Cu-I distances. However, compound 1D exhibits a contrary behavior that may be related to a change of the organic ligand's molecular configuration. These changes imply that a more significant Π-Π interaction counteracts the contraction in distances and angles when the temperature decreased. Also, the experimental conductivity measurements and theoretical calculations show a semiconductor behavior. The absorption of the 1D compound in UV, its intense emission at room temperature, and the reduction to nanometric size have allowed us to combine it homogeneously with ethyl vinyl acetate (EVA), creating a new composite material. The external quantum efficiency of this material in a Si photovoltaic mini-module has shown that this compound is an active species with application in solar cells since it can move the photons of the incident radiation (UV region) to longer wavelengths.

This study tries to provide new solutions to increase the efficiency of conversion of photons in solar cells, using photoluminescent Cu(I) coordination polymers (CPs) as possible alternative materials of lower cost, than those used today, based on lanthanides. The selected CP of chemical formula [Cu(NH2MeIN)I]n (NH2MeIN = methyl, 2-amino isonicotinate) absorbs in the utraviolet and emits in the visible region, being also easily nanoprocessable, by a simple and one-pot bottom-up approach. Nanofibers of this CP can be embedded in organic matrices such as ethyl vinyl acetate (EVA), forming transparent and homogenous films, with a thermal stability of up to approximately 150 °C. These new materials maintain the optical properties of the CP used as a dopant, ([Cu(NH2MeIN)I]n), with emission in yellow (570 nm) at 300 K, which is intensified when the working temperature is lowered. In addition, these materials can be prepared with varying thicknesses, from a few microns to a few hundred nanometers, depending on the deposition method used (drop casting or spin coating respectively). The study of their external quantum efficiency (EQE) found an increase in the UV range, which translates into an increase in the conversion efficiency. The optimal CP concentration is 5% by weight in order to not diminish the transparency of the composite material. The calculated cost on the possible incorporation of this material into solar cells shows a 50% decrease over the cost reported in similar studies based on the use of lanthanides, This article has been funded by the Spanish Ministerio de Economía y Competitividad (and the current Ministerio de Ciencia, Innovación y Universidades) (MAT2016-75883-C2-2-P, MAT2016-75716-C2-2-R and RTI2018-095563-B-100). This article is dedicated to J. J. Amo-Mora

Curie-Weiss temperature dependence of the dielectric permittivity has been shown to take place in water. A bilinear change at T*=60 oC has been reported recently. In this work an effective field st...

4 págs,; 5 figs., Ridge waveguide lasers have been fabricated on Nd doped LiNbO crystals. The fs-laser writing technique was used to define ridge structures on a gradient-index planar waveguide fabricated by Zn-diffusion. This planar waveguide was formed in a z-cut LiNbO substrate homogeneously doped with a 0.23% of Nd ions. To obtain lateral light confinement, the surface was then micromachined using a multiplexed femtosecond laser writing beam, forming the ridge structures. By butting two mirrors at the channel waveguide end-facets, forming a waveguide laser cavity, TM-polarized laser action at 1085 nm was achieved by end-fire TM-pumping at 815 nm. The waveguide laser shows a threshold of 31 mW, with a 7% of slope efficiency. © 2016 Elsevier B.V. All rights reserved, This work was supported by the Spanish Government under projects TEC2014-52642-C2-1-R and MAT2013-47395-C4.

In this work the transition probabilities, radiative lifetimes and branching ratios of Er 3+ ions in KY 1− x − y Gd x Lu y (WO 4 ) 2 crystals have been determined. With this aim, Er 3+ doped KY 1− x − y Gd x Lu y (WO 4 ) 2 crystals have been grown by means of the high temperature Top-Seeded Solution Growth. A spectroscopic analysis of Er 3+ ions in this crystal has been performed following anisotropic Judd–Ofelt analysis to obtain basic spectroscopic properties. A quantum efficiency over 97% has been determined for the 4 I 13/2 → 4 I 15/2 transition, indicating that this material is adequate for the development of lasers and amplifiers working in the third telecommunication window.

In the present work we propose a 2D-channel waveguide fabrication process based on the microstructuration of the cladding of a planar waveguide by femtosecond laser writing. The core of the waveguide is formed by a layer of KY 1− x − y Gd x Lu y (WO 4 ) 2 epitaxially grown over a KY(WO 4 ) 2 substrate by means of Liquid Phase Epitaxy (LPE). A cladding of KY(WO 4 ) 2 is then grown by LPE over the core waveguide. To obtain lateral light confinement, the cladding is then micromachined using a multiplexed femtosecond laser writing beam, forming a ridge structure. Channel waveguides fabricated following this approach have been characterized in terms of their mode sizes and propagation losses at 0.98 μm and 1.64 μm, which are close to the wavelengths of interest in lasers/amplifiers based on the Er 3+ /Yb 3+ system. Experimental data are compared with simulation analysis based on the Effective Index Method and the Beam Propagation Method, showing a good accordance between experimental and numerical results.

Reactive ion etching of RbTiOPO4 (0 0 1) substrates and (Yb,Nb):RbTiOPO4/RbTiOPO4 (0 0 1) epitaxial layers has been performed using fluorine chemistry. A maximum etch rate of 8.7 nm/min was obtained, and the deepest etch achieved was 3.5 μm. The (Yb,Nb)-doped epitaxial layers showed a slower etching rate when compared with undoped material. Liquid phase epitaxial growth of cladding layers has also been performed, resulting in a high-quality interface growth without appreciable defects. 9-mm-long Mach–Zehnder interferometer and 9-mm-long Y-splitter structures were designed and patterned in RbTiOPO4 substrates and (Yb,Nb):RbTiOPO4/RbTiOPO4 (0 0 1) epitaxial layers. The structures fabricated in RbTiOPO4 substrates were filled with laser active (Yb,Nb):RbTiOPO4 higher refractive index core material, and finally an RbTiOPO4 cladding was grown on the samples. The refractive index difference between the (Yb,Nb):RbTiOPO4 layer and the RbTiOPO4 substrate at 1.5 μm has been measured and optical waveguiding at this wavelength has been demonstrated.

Recently, the paraelectric response of water was investigated in the range 0–100 °C. It showed an almost perfect Curie–Weiss behaviour up to 60 °C, but a slight change in slope of 1/ed versus T at 60 °C was overlooked. In this work, we report optical extinction measurements on metallic (gold and silver) nanoparticles dispersed in water, annealed at various temperatures in the range from 20 to 90 °C. An anomalous response at 60 °C is clearly detectable, which we associate to a subtle structural transformation in the water molecules at that temperature. This water anomaly is also manifested by means of a blue shift in the longitudinal surface plasmon resonance of the metallic nanoparticles for the solutions annealed at temperatures higher than about 60 °C. A reanalysis of 1/ed (T) for water in the whole temperature range leads us to conclude that the water molecule undergoes a subtle transformation from a low temperature (0–60 °C) configuration with a dipole moment μ1 = 2.18 D (close to the molecular dipole...

We report a systematic investigation on the temperature dependence of fluorescence decay dynamics of infrared emitting colloidal Ag2S nanocrystals (NCs) with different surface coatings. The drastic lifetime reduction in the biological temperature range (20–50 °C) makes Ag2S NCs outstanding candidates for high sensitivity subcutaneous lifetime-based thermal sensing in the second biological window (1000–1400 nm). Indeed, the lifetime thermal sensitivity of Ag2S NCs has been found to be as large as 3–4% °C−1 at an operating wavelength of 1250 nm. Their application for lifetime-based luminescence nanothermometry has been demonstrated through simple ex vivo experiments specially designed to elucidate the magnitude of subcutaneous thermal gradients. Experimental data were found to be in excellent agreement with numerical simulations.

This paper presents a study of the behaviour as optical superlattices of periodically poled LiNbO3 and LiTaO3 crystals using the Scanning Near-field Optical Microscopy (SNOM) technique. The periodic ferroelectric domains were formed either by electric field poling technique or by the “off-centre Czochralski method” during crystal growth. SNOM patterns were recorded in both collective and reflective configuration, simultaneously with surface topography measurement by AFM (Atomic Force Microscopy). It has been found that regardless of the method used to create the domains, a modulation in the SNOM signal intensity is correlated with the ferroelectric domain structure. The maximum intensity of the collected or reflected SNOM light intensity is centred on the negative domains, whereas the minimum intensity is positioned on the positive domains. This result demonstrates that the modulation of the refractive index is related to the domains and not with the wall between them.

We report on a unique combination of high-resolution confocal microscopy and ratiometric luminescence thermometry to obtain thermal images of 800 nm pumped ultrafast laser-inscribed waveguides in a Nd:YAG crystal. Thermal images evidence a strong localization of thermal load in the waveguide active volume. Comparison between experimental data and numerical simulations reveals that ultrafast laser-inscribed damage tracks in Nd:YAG crystals behave both as low-index and low-thermal conductivity barriers., This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO) under grants MAT2013-47395-C4-1-R and FIS2013-44174-P and from Junta de Castilla y León (Project SA116U13, UIC016).

M.A. Butt, M.C. Pujol, R. Solé, A. Ródenas, G. Lifante, M. Aguiló, F. Díaz, S. N. Khonina, R. V. Skidanov and Payal Verma, "Fabrication of optical waveguides in RbTiOPO4 single crystals by using different techniques", XIII International Scientific and Technical Conference on Optical Technologies in Telecommunications,SPIE 9807 (26 March, 2016): doi: 10.1117/12.2231368. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited, Proceedings of XIII International Scientific and Technical Conference on Optical Technologies in Telecommunications Conference (Ufa, Russian Federation), In this work, we have demonstrated the use of different technologies to fabricate straight channel waveguides, S-bend waveguides, Y-splitter and Mach -Zehnder (MZ) structures on RbTiOPO 4 crystals and its isomorphs. We used reactive ion etching (RIE), inductively coupled plasma-RIE (ICP-RIE), femtosecond pulse laser micro-fabrication and ion diffusion techniques to structure these crystals. Computer simulations have been carried out and compared with the optical characterization of the waveguides which are in agreement with each other., This work is supported by the Ministry of Education and Science of the Russian Federation, Russian Science Foundation (grant No. 14-19-00114), Spanish Government under Projects MAT2011-29255-C02-02, TEC2014-55948-R, MAT2013-47395, C4-4-R/1-R and by the Catalan Authority under Project 2014SGR1358

We report on the use of the Erbium-based luminescence thermometry to realize high resolution, three dimensional (3D) thermal imaging of optical waveguides. Proof of concept is demonstrated in a 980-nm laser pumped ultrafast laser inscribed waveguide in Er:Yb phosphate glass. Multi-photon microscopy images revealed the existence of well confined intra-waveguide temperature increments as large as 200°C for moderate 980-nm pump powers of 120 mW. Numerical simulations and experimental data reveal that thermal loading can be substantially reduced if pump events are separated more than the characteristic thermal time that for the waveguides investigated is in the millisecond time scale, This work has been supported by the Ministerio de Economía y Competitividad of Spain (MINECO) (FIS2013-44174-P, MAT2013-47395-C4-1-R) and National Natural Science Foundation of China (NSFC) (11274203)

We report on the fabrication of stress-induced waveguides in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) by simultaneous double-beam irradiation with femtosecond laser pulses. An interferometer was used to generate two femtosecond laser beams that, focused with certain lateral separation inside the crystal, produced two parallel damage tracks with a single scan. The propagation of the mechanical waves simultaneously created in both focal spots produced a highly symmetrical stress field that is clearly revealed in micro-luminescence maps. The optical properties of the double-beam waveguides are studied and compared to those of single-beam irradiation, showing relevant differences. The creation of more symmetric stress patterns and a slight reduction of propagation losses are explained in terms of the fact that simultaneous inscription allows for a drastic reduction in the magnitude of “incubation” effects related to the existence of pre-damaged states., This work was supported by the Ministerio de Economía y Competitividad under Projects FIS2013-44174-P and MAT2013-47395- C4-1-R. The femtosecond laser inscription was carried out in the Spanish Pulsed Laser Center (CLPU) with their Laser Service (High-Repetition-Rate laser system) and their technical assistance, in the framework of the access agreement concerning USAL staff.

Fifty years since the invention of the laser have been witness of the development of many different laser systems and designs. Among them, miniaturized versions of solid sate lasers based on rare-earth-doped dielectric materials have been proposed and demonstrated during the last 20 years. They are based on confined radiation provided by optical waveguide structures. Although many materials and techniques have been studied for producing planar and channel waveguides, only a few of them have shown to be adequate routes for fabricating waveguide lasers. Here we summarize the theory and specific technologies developed for characterizing waveguide structures, and we present some common fabrication techniques already successfully applied to fabricate dielectric waveguide lasers, where relevant examples of demonstrated working devices are outlined.

CW mirrorless laser operation at 1840 nm at room temperature was observed in buried rib waveguides of KY0.58Gd0.22Lu0.17Tm0.03(WO4)2 fabricated by structuring KY(WO4) substrates by Ar-ion milling and subsequent liquid phase epitaxial growth of the active layer on these substrates. Laser efficiency and laser threshold seems to change with the width of the channels fabricated.

This work reports the behaviour of the absorption coefficient in a C2+-implanted Nd:YVO4 crystal by successive annealing steps. The absorption coefficient was monitored with respect to time and temperature after an annealing process. Firstly, the annealing duration increased in a constant form keeping a constant temperature and secondly, the annealing temperature was increased with equal time intervals. The results indicate that the variation of the absorption coefficient has an exponential behaviour.

We show how the ultrafast laser inscription of nanodimple arrays enables near-field local enhancement in high refractive-index crystals. We first demonstrate both experimentally and numerically how, when two nanodimples are separated by intermediate distances (700–1000 nm), near-field interference can take place resulting in a near-field enhancement between nanodimples. Based on this effect, near-field enhancements close to 60% are then demonstrated at the center of nanodimple arrays, and strong optical contrasts in excess of 100% are produced. The integration of these arrays into crystal substrates provides a versatile tool for new optical trapping and evanescent-field nanosensing devices.

This paper summarizes the main results we obtained in our laboratories in relation with crystalline layers obtained by Liquid Phase Epitaxial growth of lanthanide doped KLu(WO 4 ) 2 and Nb:RbTiOPO 4 grown on KLu(WO 4 ) 2 and RbTiOPO 4 substrates, respectively. Macroscopic defect free epitaxial layers were grown and characterized in terms of their compositional homogeneity, structural stress in the layer/substrate interface and laser and waveguiding performances.

Here we show the results we obtained in the fabrication of planar waveguide lasers based on monoclinic double tungstates doped with Er 3+ and Tm 3+ . We have successfully introduced these ions into the lattice matched KY 0.59 Gd 0.19 Lu 0.22 (WO 4 ) 2 epitaxial layers grown on KY(WO 4 ) 2 substrates without loss of optical quality and keeping a high refractive index contrast between the epitaxial layer and the substrate. We characterized the waveguiding properties of these epitaxial layers at λ = 632.8 nm by dark modes spectroscopy, and we showed that these waveguides can support several TE and TM modes. Spectroscopic characterization of the active lanthanide ions in these crystals is also presented.

This paper presents a study of the near-field optical profile of corrugated surfaces obtained from commercial digital versatile disk (DVD) patterns using a scanning near-field microscope (SNOM). The profile of the SNOM light intensity collected is related to the topography of the samples. The SNOM patterns consist of a periodic modulated light intensity along the corrugated surface with the same periodicity of the topography structure. For the virgin sample, the light profile has intensity peaks corresponding to the ridges of the DVD structure. However, when the corrugated surface is metalized with a thin gold film of 30 nm thick, the SNOM light intensity peaks are centred in the valley of the DVD structure. A Finite-Difference Time-Domain (FDTD) model has been employed to simulate the SNOM experimental data.

Zinc-diffused channel waveguides fabricated in thulium-doped LiNbO3 have been analyzed by means of confocal micro-luminescence techniques. Modifications induced by Zn2+ ions in the doped-crystal substrate are characterized following the evolution of the 3H4→3H6 luminescence of thulium ions at 795 nm, showing the existence of two different regions in the waveguide. Several Raman modes of LiNbO3 have been used as well to study the differences between the waveguide and the bulk material.

This work shows a study of the periodic ferroelectric domains formed in LiNbO3 crystals doped with rare earths by means of scanning near field optical microscopy (SNOM) technique. It has been observed periodic structures associated with ferroelectric domains with an unexpected high value of the optical contrast working under reflectance SNOM mode. From Raman-Nath diffraction patterns, a refractive index modulation of Δ n ∼ 1 0 − 4 has been calculated. These results were correlated with the ferroelectric periodic domains obtained by the SNOM technique. A light waveguide effects along the ferroelectric domains is suggested to explain the high reflectance contrast observed in SNOM experiments.

The main purpose of this work was the determination of the composition of a KY 1-x-y Gd x Lu y (WO 4 ) 2 layer grown by liquid phase epitaxy (LPE) technique on KY(WO 4 ) 2 substrate having enough refracave index contrast and appropriate lattice mismatch (f hkl ) to act as planar waveguides. To achieve this we have grown KY 1-x-y Gd x Lu y (WO 4 ) 2 single crystals by the flux method and characterized them in terms of chemical composition, structure and refractive indices. A high quality epitaxial layer of KY 0.58 Gd 0.22 Lu 0 . 20 (WO 4 ) 2 with a thickness of 10 μm was grown on a b oriented KY(WO 4 ) 2 substrate by LPE. At λ = 632.8 nm this planar waveguide can support five and four guided modes along the N g and N m directions, respectively and five TM modes along N p direction.

The effect that femtosecond laser filamentation has on the refractive index of Nd:YAG ceramics, and which leads to the formation of waveguide lasers, has been studied by micro-spectroscopy imaging, beam propagation experiments and calculations. From the analysis of the Nd3+ luminescence and Raman images, two main types of laser induced modifications have been found to contribute to the refractive-index change: (i) a lattice defect contribution localized along the self-focusing volume of the laser pulses, in which lattice damage causes a refractive-index decrease, and (ii) a lattice strain-field contribution around and inside the filaments, in which the pressure-driven variation of the inter-atomic distances causes refractive-index variations. Scanning near-field optical-transmission and end-coupling experiments, in combination with beam propagation calculations, have been used to quantitatively determine the corresponding contribution of each effect to the refractive-index field of double-filament waveguides. Results indicate that the strain-field induced refractive-index increment is the main mechanism leading to waveguiding, whereas the damage-induced refractive-index reduction at filaments leads to a stronger mode confinement.

This paper reports on the spectroscopy properties, absorption and luminescence, of Cr3+ ions in singly doped, ZnO-codoped, and Zn in-diffused LiNbO3:Cr crystals. In addition to the broad absorption, inter-ionic transitions ascribed to Cr3+ ions located in Li+ and Nb5+ sites; [Cr]Li and [Cr]Nb centres two absorption bands at higher energy are reported and ascribed to the charge transfer transitions of the Cr3+ ions of the two defect centres. The charge transfer transitions are used as optical probe to study the role of the Zn ions in the Zn in-diffused LiNbO3:Cr samples. It has been observed that the Zn-in-diffused processes created [Cr]Nb centres in the diffusion zone. The location of the diffused Zn2+ ions is considered to be in Li+ site, displacing the Cr3+ ions from the Li+ sites, [Cr]Li, to the Nb5+ positions, [Cr]Nb.

In this work, Scanning Near Field Microscopy (SNOM) observation and characterization of quasi-periodic ferroelectric domains in rare earth doped LiNbO 3 , Nd doped Ba 2 NaNb 5 O 15 , and LiTaO 3 crystals are presented. The formation of ferroelectric domains has been induced either during the crystal growth procedure (LiNbO 3 and Ba 2 NaNb 5 O 15 ) or by applying pulsed electric field (LiTaO3). SNOM reflection, transmission and collection modes have been used indistinctly to characterize the ferroelectric domain structure. In the three crystals under study, an unexpected optical contrast associated to the presence of ferroelectric domains has been observed. In particular, working in the SNOM collection mode the optical contrasts reached a value closed to ∼ 80% in Ba 2 NaNb 5 O 15 and LiTaO 3 crystals. These high optical contrast values are explained considering that the ferroelectric domains pattern operates as a periodic array of planar waveguides (optical super-lattices). The invoked light-pipe mechanism...

Absorption and emission cross-sections are essential spectroscopic parameters that determine the performance of rare-earth solid state lasers and amplifiers. A precise characterization of such parameters is of great interest in order to proceed with the necessary optimization stage which will assure the development of photonic devices with high efficiency. In particular, in order to model Tm 3+ infrared lasers under 800 nm pumping, the absorption and emission cross-sections associated with optical transitions involving the 3 H 4 and 3 F 4 manifolds are needed. In this work, the classical McCumber theory is applied to evaluate the polarized absorption and emission cross-sections of Tm 3+ ions in LiNbO 3 .

The infrared optical properties of LiNbO 3 crystals doped with variable thulium concentrations have been studied. In particular, the infrared emissions that appear after direct pumping to the 3 H 4 multiplet (795 nm) have been analyzed. The emission spectra, as well as the lifetimes, show that an efficient energy transfer between 3 F 4 and 3 H 4 levels takes place. The concentration dependence of the lifetimes has been studied and the transfer probability has been characterized.

In this paper we report on experimental evidence of laser light confinement between ferroelectric domains in the neodymium doped Ba2NaNb5O15 ferroelectric crystal. High contrast near field optical microscopy images have been obtained as a consequence of the periodic modulation in the refractive index caused by the presence of 2D antiparallel ferroelectric domains.

The simulation of light propagation using standard beam propagation techniques, in periodically inverted domains in Ba2NaNb5O12 crystals is presented. The poled domains pattern gives rise to periodic modulation of the refractive index in the crystal, which can be observed with diffraction experiments and simulated by one-dimensional beam propagation methods. The micro-domains are characterized by Scanning Near Field Microscopy, using both transmission and collection modes. In particular, under the collection mode, micro- pictures have been obtained with unexpected high optical contrast between positive and negative domains of up to 80%. Using a beam simulation method, the results are explained considering that the ferroelectric domains operate as a periodic array of planar waveguides.

The electro-optic coefficients r 33 and r 13 and the second order susceptibility χ (2) 33 have been measured in Zn-in-diffused waveguides on congruent LiNbO 3 . Absolute measurements of r 33 and r 13 have been carried out with a Mach-Zehnder modulating technique and the obtained values, r 33 = 14.6 ± 0.9 pm/V and r 13 = 3.3 ± 0.2 pm/V, show an appreciable decrease with regard to that of congruent LiNbO 3 . Measurements of χ (2) 33 relative to the substrate have been performed in the strong absorption regime and the obtained value equals that of bulk LiNbO 3 .

The luminescence properties of Neodymium ions in Zn diffused LiNbO3 channel waveguides have been studied with sub-micrometric spatial resolution. The analysis of the luminescence spectra suggests the existence of a local expansion and disordering associated to the presence of Zn in the LiNbO3 lattice after the diffusion process. By taking this cause–effect relation into account, it has been possible to determine both the in-depth and lateral Zn diffusion lengths, as well to elucidate the spatial location of the channel waveguide.

Sb2S3 thin films have been obtained by physical vapour deposition on LiNbO3 and glass substrates. Films with amorphous structure originally became polycrystalline by annealing in a sulfur atmosphere. Changes in optical and structural properties have been studied as a function of annealing temperature. A drastic variation in optical transmission, energy gaps, refractive index, crystallite size, etc is observed at a temperature near 200 °C.