A. Boudrioua

Structural and optical properties of rare-earth-doped Y2O3 waveguides grown by pulsed-laser deposition

Crystalline rare-earth-doped yttrium oxide thin films were grown by pulsed-laser deposition (PLD) on SiO2/Si substrates. The structural and morphological features of these films were studied, as a function of the growth conditions (temperature from 200 to 800 °C and oxygen pressure from 10−6 to 0.5 mbar), by using Rutherford backscattering spectroscopy, x-ray diffraction, and atomic force microscopy. The related optical properties were investigated by m-lines spectroscopy at 633 nm and 1.3 μm. The optimal conditions were found to be a temperature and a pressure of 700 °C and 10−6 mbar, respectively. In that case, the Y2O3 films are stoichiometric with controlled erbium and europium rates, and present a well-crystallized, (111) textured cubic phase and a low surface roughness of about 10 A. Moreover, the PLD films show good waveguiding properties with a high refractive index (1.92 at 633 nm), a step-index structure, and low optical losses around 1 dB/cm in the near infrared region, promising for a planar a...

New approach for loss measurements in optical planar waveguides

Abstract A new nondestructive method for measuring waveguide losses is presented. It uses a prism-in coupling method to feed the light into the waveguide and the end-fire coupling to measure the transmitted light. It is simple both in construction and during the measurements. Such a configuration enables us to determine the attenuation coefficient which is independent of coupling efficiencies into and out of the guide and of the laser fluctuation. The results obtained, with this method, on H + and He + implanted LiNbO 3 waveguides are presented and discussed. Therefore, the measurements lead to the calculation of the attenuation with an absolute incertitude of 0.4 dB cm −1 for a waveguide length of 0.4 cm.

Nonlinear optical properties of (H + ,He + )- implanted planar waveguides in z-cut lithium niobate: annealing effect

Reflection second-harmonic generation from the polished waveguide end face was used to investigate the nonlinear properties of LiNbO3-implanted waveguides fabricated by use of 2-MeV He+ and 1.5-Mev ...

Second-harmonic generation in He + -implanted gadolinium calcium oxoborate planar waveguides

What is believed to be the first investigation of second-harmonic generation (SHG) in Ca(4)GdO (BO(3))(3) waveguides is reported. A planar waveguide was formed by 2-MeV-helium implantation. We cut the sample to achieve type I noncritical phase matching of an 823-nm fundamental wave for fundamental light propagating along the y axis and polarized along the z crystallophysic axis of the crystal. SHG was achieved with a relatively low pumping power of a cw Ti:sapphire laser. The results indicate that the nonlinearity of the material remains in the guiding region after ion implantation.

Epitaxial PbTiO3 thin films grown on (100) MgO by pulsed-laser deposition for optical waveguiding properties

Perovskite single phased PbTiO3 thin films have been grown by pulsed-laser deposition on (100) MgO single crystals in order to prepare high quality optical waveguides. The substrate temperature and the oxygen pressure during the deposition have been optimized to improve crystalline quality and to grow epitaxial thin films. The films display two main axis orientations according to the MgO (100) basal plane. The waveguiding properties and the optical losses characterized by using m-lines spectroscopy and charge-coupled device camera measurement, respectively, are correlated to the structural properties of the films. Such textured and epitaxied films display very good optical properties, as the optical losses are found to be lower than 1 dB cm−1.

Formation of planar optical waveguides in the new nonlinear gadolinium calcium oxoborate, Ca(4)GdO(BO(3))(3), crystal by 2-MeV He(+) implantation.

A planar waveguide composed of the new nonlinear material, Ca(4)GdO(BO(3))(3) (GdCOB), is reported. This crystal belongs to the calcium oxoborate family. It has attractive nonlinear properties that can be of great interest in integrated optics applications. We used a method of He(+) implantation to fabricate waveguides in GdCOB crystals by creating a buried layer of lowered refractive index a few micrometers beneath the surface. Both TE and TM modes were observed. Therefore, according to the Y cut of the crystal, refractive-index values of n(x) , n(y) , and n(z) were obtained. Index profiles were reconstructed by an improved inverse WKB method. The profiles showed a steplike index behavior, indicating that the guiding region obtained was of good optical quality.

Implanted waveguides in borate crystals (LTB, β-BBO, and LBO) for frequency conversion

Abstract Helium implantation is used to produce optical waveguides in LTB, β-BBO and LBO materials. These waveguides present a step index behavior revealing a good optical quality of the guiding region with losses in the range 2–5 dB cm−1. The annealing process at 200°C during 2–24 h showed a good stability of the guiding region with a slight decrease of the optical losses. Preliminary results of SHG in LBO:He+ waveguides are reported.

Effective nonlinear coefficients of organic powders measured by second-harmonic generation in total reflection: numerical and experimental analysis

A second-harmonic wave generated by an evanescent wave (SHEW) is used to measure the effective nonlinear coefficient of organic materials in powder form. The SHEW signal is less sensitive than the powder method to the phase-matching conditions of the material. For this reason, the SHEW technique can be used to survey a wide variety of samples. The effective nonlinear coefficient and the refractive indices of the sample are obtained as fitting parameters. The influence of experimental conditions on the fitting process is discussed. The results obtained from our powders are compared with the nonlinear coefficients of the same materials in bulk crystal form. Good agreement is found between experimental results and literature values.

Waveguiding properties of pulsed-laser deposition Ca4GdO(BO3)3 thin films

Abstract Waveguiding properties of stoichiometric Ca4GdO(BO3)3 (GdCOB) thin films deposited on quartz substrates by the pulsed-laser deposition (PLD) technique are reported. The optical properties and the anisotropy of the obtained thin films are investigated using the prism-coupling technique. Refractive indices (nx=1.666, ny=1.673 and nz=1.680 at 632.8 nm) were, respectively, determined from the transverse electric (TE) and the transverse magnetic (TM) mode excitations. These values are found to be 3% lower than those of the bulk material, which is likely due to the structural and morphological features of the deposited GdCOB films.

Linear and nonlinear optical properties of implanted Ca4GdO(BO3)3 planar waveguides

We report on a detailed investigation of optical planar waveguides fabricated in the new nonlinear Ca4GdO(BO3)3 crystal by ionic implantation. Both single and multiple He+ implantations are investigated. Second-harmonic generation (SHG) in He+ multiple-implanted samples are achieved by type I phase matching for fundamental light propagating along the y axis and polarized along the z axis at 823 nm and for light propagating along the x axis and polarized along the z axis at 960 nm. SHG operates with low-power pumping of a cw Ti:sapphire laser. Analyses of SHG within the waveguides are presented. The results indicate that the nonlinearity of the material remains in the guiding area after ion implantation. The conversion efficiency was found to be ∼10−2. This value is increased by ∼10% after 1 h annealing at 220°C.