Search results for "Lithium niobate"

Anomalies of dielectric properties and conductivity in single domain LiNbO3:Zn crystals

2016

ABSTRACTA study of the temperature dependence of dielectric constant, conductivity, and piezoelectric modulus in the single-domain state of LiNbO3 crystals modified by Zn admixture at threshold concentration is reported. Unipolarity of the LiNbO3:Zn crystals is observed to increase after treatment of brand-new samples by high-temperature electro-diffusion annealing and by subsequent high-temperature annealing of short-circuited samples. The observed effects are explained as a result of meta-stable residual domains collapsing at high temperature the collapse being assisted by disintegration of charged clusters stabilizing domain walls. The rise of unipolarity is accompanied by anomalies on t…

All-Optical frequency Shifter in a Periodically Poled Lithium Tantalate Waveguide

2011

A frequency shifting device is fabricated and tested in a congruent Lithium Tantalate waveguide. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained, demonstrating a two-stage parametric conversion.

Control of signal coherence in parametric frequency mixing with incoherent pumps: Narrowband mid-infrared light generation by downconversion of broad…

2012

International audience; We study, with numerical simulations using the generalized nonlinear envelope equation, the processes of optical parametric and difference- and sum-frequency generation (SFG) with incoherent pumps in optical media with both quadratic and third-order nonlinearity, such as periodically poled lithium niobate. With ultrabroadband amplified spontaneous emission pumps or continua (spectral widths > 10 THz), group-velocity matching of a near-IR pump and a short-wavelength mid-IR (MIR) idler in optical parametric generation may lead to more than 15-fold relative spectral narrowing of the generated MIR signal. Moreover, the SFG process may also lead to 6-fold signal coherence…

Continuous-Wave Backward Frequency Doubling in Periodically Poled Lithium Niobate

2010

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2008

Raman studies of ostensibly pure congruent, close to stoichiometric and stoichiometric lithium niobate single crystals and single crystals of lithium niobate containing admixture of Gd3+, Y+, and Mg2+ are reported. The authors have revealed weak Raman bands anomalously narrowing at changes of crystal composition disordering the cation sublattice and discuss the results with regard to evidence of anomalous ordering of structural units of the cation sublattice occurring at disordering of the cation sublattice as a whole.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Storage of information in lithium niobate single crystals

2011

Reported studies of recording information were made with a number of LiNbO 3 compositions: stoichiometric and congruent single crystals. The present study shows that recording is possible in pure LiNbO 3 single crystals and in single crystals containing inactive cation dopants. Recording in stoichiometric crystals is likely possible because of a considerable amount of electrons localised in shallow traps. Absence of recorded information in pure congruent crystals were observed.

Mechanisms of Solid Phase Interaction at Synthesis of the Mixture for Ferroelectric Lithium Niobate

2011

Results of a complex differential thermal analyses (DTA, TGA), X-ray diffraction analyses, infrared and mass-spectrometry study of solid-state interactions in the Li2CO3- Nb2O5 system are reported.

Fabrication and Characterisation of Reverse Proton Exchange Optical Waveguides in Neodymium Doped Lithium Niobate Crystals

2005

In this work, the complete fabrication process which combines Proton Exchange (PE) and Reverse Proton Exchange (RPE) in Neodymium doped LiNbO3 channel waveguides is reported. To produce the PE-RPE channel waveguides the fabrication of dielectric SiO2 masks had to be implemented. For this propose, we adopted a technique based on the Ion Plating Plasma Assisted Deposition of SiO2 followed by the standard ultraviolet photolithographic patterning. On the other hand, we determined the main optical and spectroscopic properties of Nd3+ ions in the channel waveguides including the study of the lifetime as function as the polarisation.

An Example of Ti:LiNbO3 Device Fabrication: The Mach-Zehnder Electrooptical Modulator

1994

Integrated optics on LiNbO3 has already reached a stage of maturity. Several manufacturers are producing standard and custom devices on LiNbO3 such as high speed (up to 20 GHz) phase and intensity modulators, switching matrices, hybrid optical gyroscopes, etc.1. Two techniques are commonly used to fabricate these devices: titanium indiffusion for 1.3 and 1.5 μm wavelength operation and annealed proton exchange (APE) at 0.8 μm, due to its higher power handling capacity.

Nonstoichiometric silica mask to fabricate reverse proton-exchange waveguides in lithium niobate crystals

2004

Producing channel waveguides requires a photolithographic mask, but the standard technique of using thermally evaporated metal films for proton exchange has proved to be unsuitable for withstanding the rather aggressive process of reverse proton exchange. We report the fabrication of a nonstoichiometric silica mask by ion-plating plasma-assisted deposition. This mask is strong enough to resist both direct and reverse proton exchange and is also compatible with anisotropic dry etching for patterning the mask and with electric field poling. Our technique is a practical alternative to the use of SiO2 sputtered masks.