Формування дослідницьких умінь учнів старших класів у процесі навчання інформатики

(uk) У статті розглядається формування дослідницьких умінь учнів у навчанні інформатики з використанням роздаткового матеріалу, що дає змогу учню глибоко засвоїти навчальний матеріал.(ru) В статье рассматривается формирование исследовательских умений учеников в обучении информатике с использованием раздаточного материала, который дает возможность им глубоко усвоить учебный материал

Surface behaviour of nco species on Rh(111) and polycrystalline Rh surfaces

Quasi-phase-matching (QPM) is a method to get tailored efficient second order nonlinear interactions [1]. Several techniques exist for fabrication of periodic domain structures in ferroelectric crystals for QPM frequency conversion. By far, electric field poling using lithographically patterned electrodes on the z-face of the crystal is the most common one [2]. High-quality periodically inverted ferroelectric domain structures in flux grown KTiOP 4 (KTP) crystals were fabricated already in the late 90's using this technique [3], and recently periodic domain sizes of few hundred nanometers were fabricated in 1 mm thick samples thanks to the quasi-one dimensional structure of KTP. It has recently also been shown that a slight Rb doping of the KTP crystal (RKTP) facilitates the periodic poling [4]. However, fabrication of two-dimensional (2D) domain structures in RKTP has not yet been investigated. A disadvantage with the lithographic patterning is that each sample needs to be patterned individually, which is tedious and time consuming. Moreover, when it comes to the small domain features, which are required by the next generation of nonlinear optical devices, a more versatile poling technique has to be developed due to the limitations of conventional photolithography. Structured silicon has been investigated as an alternative electrode for formation of 1D domains by contact poling in LiNb3 [5]. However, these electrodes were fabricated by wet etching and the sample thickness was limited to ∼200 μm.QC 20140619</p

Bulk PPKTP by crystal growth from high temperature solution

International audiencePeriodically-poled ferroelectric crystals show unprecedented efficiency and properties otherwise impossible to obtain. Unfortunately, the sample thickness obtainable today limits their use to low and moderate power application. With the aim of increasing the size of periodically domain-structured crystals with a controlled and regular grating period, we proposed an epitaxial growth process using seeds made of thin plates domain engineered by electric field poling. We demonstrated this process with the ferroelectric crystal KTiOPO4 (KTP) which is one of the most promising candidate materials for that purpose. The poling step requires a sample exhibiting (001) and (00 (1) over bar) faces, so that the growth step has to be performed onto these faces. This constraint is a difficulty to circumvent as these faces are not present in the standard equilibrium morphology. It is then necessary to find the growth conditions enabling to work below the roughening temperature of these faces. By using a high temperature solution method, the so-called "flux method", and by choosing an appropriate chemical composition of the flux solution, we obtained periodically domain-structured KTP layers with thicknesses up to 800 mu m and regular periodicity onto (001) and (00 (1) over bar) faces of the initial PPKTP seeds

Sub-nanosecond, 1-10 kHz, low-threshold, non-critical OPOs based on periodically poled KTP crystal pumped at 1,064 nm

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Nonlinear optics with diode lasers

Abstract -Diode lasers are under constant development and we see broader spectral coverage, increased output power and higher reliability. Nonlinear optical applications sets special requirement on the laser source, which not always are easily compatible with diode lasers. In this presentation a review will be given of the possibilities and difficulties of using diode lasers in nonlinear optics

Advances in lasers and optical micro-nano-systems

[No abstract available

Laser cladding of transparent fused silica glassusing sub-μm powder

Fused silica glass is a commonly used high-performance material. However, due tothe high temperature necessary for its production, manufacturing can also be challenging andcostly. An attractive approach is additive manufacturing through laser cladding. Laser claddingof transparent fused silica was achieved using a CO2-laser to locally melt the substrate whileinjecting a stream of fumed silica glass powder into the melt-pool. By the described technique, itis possible to manufacture fully sintered silica glass with deposition rate up to 29 mm3/min. Inthis work we have studied deposition dynamics and influence of different process parameters onthe final deposition quality.QC 20210917</p