Sergey S. Mushinsky

Water Effect on Proton Exchange of X-cut Lithium Niobate in the Melt of Benzoic Acid

The influence of controllable amount of water admixture (up to 0.5 w.%) in benzoic acid on the proton exchange process of X-cut congruent lithium niobate was studied in this paper by means of mode spectroscopy, optical microscopy, optical profilometry, atomic force microscopy, XRD, and chemical etching. It has been determined that addition of 0.5 w.% Н2О to benzoic acid increases proton exchange rate and changes phase composition and number of defects of proton exchanged layer in lithium niobate.

Influence of lithium niobate sublayer structure to refractive index of optical waveguides

ABSTRACT Samples cleaning in ammonia-peroxide solution (APS) leads to increase of waveguides contrast after proton exchange comparing with the waveguides without APS cleaning. Surface and sublayer of lithium niobate was studied by optical microscopy, scanning electron microscopy and X-ray diffraction. It was detected many of multidirectional scratches on surface of lithium niobate and defective sublayer till a depth of 6 μm. These facts are important for manufacture of integrated optical circuits: repeatability, waveguide optical loss and circuit drift parameters.

Structural properties of silicon oxide prepared by high-power PECVD

The paper presents results of structure analysis of silicon oxide films prepared by plasma enhanced chemical vapor deposition (PECVD) methods with a high power plasma excitation. The films were deposited from hexamethyldisilazane and oxygen mixture. Dependences on deposition parameters are presented.

Use of method for chemical etching for identification of structure of proton exchange channel waveguides fabricated on Z-cut of lithium niobate crystal

It was established by chemical etching that proton exchange on the surface of LN +Z cut in the molten benzoic acid at the temperature of 190°…210°С during 1…4 h causes fabrication of channel waveguides, consisting of 3 proton exchange phases.

Structure and properties of proton exchange waveguides on Z cut of lithium niobate crystal fabricated in molten benzoic acid with the addition of lithium benzoate

Methods of chemical etching, non-contact profilometry, X-ray analysis and mode spectroscopy enabled to find out that proton exchange channel waveguides formed on Z cut of lithium niobate crystal in the molten benzoic acid with the addition of 3 mol.% of lithium benzoate at the temperature of 225°C were composed of κ2-phase and a thin layer of α-phase. Proton exchange on +Z and -Z faces of the lithium niobate crystal in benzoic acid (with or without the addition of lithium benzoate) occurs at the same rate.

Domain inversion of optical channel waveguides on lithium niobate

Feasibility of electrode-less sensor to measure the external electric field intensity is shown by forming on a single lithium niobate crystal, firstly, the channel waveguides by proton exchange with the following annealing, and then - domain area with specified topology in one of the arms of the interferometer.

Photoluminescence in Functionalized/Doped Graphene Quantum Dots: Role of SurfaceStates

Photoluminescence in Functionalized/Doped Graphene Quantum Dots: Role of Surface States It has been shown that functionalization/doping of Graphene Quantum Dots (GQDs) can lead to further tuning of their already existing band gap. We have successfully functionalized GQDs (synthesized by hydrothermal process) with oxygen, hydrogen, fluorine, and doped with nitrogen using capacitively coupled plasma of respective gas as evidenced by Raman and X-ray photo emission spectroscopy (XPS). Room temperature photoluminescence (PL) of each functionalized GQD shows distinctive features and can be explained as due to charge transfers between the functional groups/dopants and GQDs as well as presence of mid gap states as a result of functionalization and doping. An energy diagram model is proposed to elucidate the PL modulation resulting from functionalization and doping.

Structural phase transformations of proton-exchanged layers of lithium niobate during annealing

ABSTRACT Kinetics of phase transitions in the surface layer of proton-exchanged planar waveguides on X-cut of lithium niobate crystal during annealing at 330, 350, and 370°C was investigated by optical methods (dark field microscopy, crossed-polarizers bright field microscopy, and mode spectroscopy). Nucleation and growth stages of phase transformations were identified. Based on mode spectroscopy data and analysis of previous works, we assume that transformation of κ2-phase into κ1-phase and further transformation into α-phase were observed during experiment.

Effect of pre-annealing process on the surface roughness of ridge waveguides formed with wet etching of –Z-cut LiNbO3

ABSTRACT It is shown that for decreasing the surface roughness of ridge waveguides formed on the –Z-cut of LiNbO3 with wet etching it is useful to carry out the annealing of the sample with formed Cr-mask layer prior to the etching. The reason is in Cr-layer inheritance of the near-surface defects of LiNbO3 substrate and disclosure of these defects during the etching process. It was confirmed by methods of scanning electron, optical dark field and bright field microscopies of initial and annealed LiNbO3 etched under different conditions.

FTIR research of protective PECVD coating for electro-optical devices

The paper presents results of FTIR analysis of silicon organic thin films prepared by plasma enhanced chemical vapor deposition methods. The films were deposited from hexamethyldisilazane and oxygen mixture. Refractive index and deposition rates were obtained. Dependencies on plasma source power are presented. Possibility to prepare films with variable properties during deposition was demonstrated.