Synthesis, crystal growth and second harmonic generation properties of trivalent rare-earth-doped non-linear tungsten–bronze-type structure Ba2Na1−3xRExNb5O15 (RE=Sc, Y, La, Gd, Yb and Lu) (original) (raw)
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Optical second harmonic generation properties of BiB3O6
Optics Express, 2004
We present studies of the optical properties of the new nonlinear material BiB 3 O 6 for second harmonic generation from the visible to infrared. We have determined the phase-matching conditions and effective nonlinear coefficients in the three principal optical planes, acceptance bandwidths, spatial and temporal walkoff, group velocity dispersion and double phase-matching behaviour. We also report on experimental studies in this material, where efficient, high-average-power second harmonic generation of femtosecond pulses into the blue is demonstrated. Using 130-fs fundamental pulses at 76 MHz, single-pass second harmonic average powers as much as 830 mW at greater than 50% conversion efficiency have been generated over a tunable range of 375-435 nm. Using cross-correlation measurements in a 100µm β-BaB 2 O 4 crystal second harmonic pulse durations of 220 fs are obtained. Our theoretical findings are verified by experimental data, where excellent agreement between the calculations and measurements is obtained. Direct comparison of BiB 3 O 6 with β-BaB 2 O 4 also confirms improved performance of this new material for second harmonic generation of femtosecond pulses.
The Ba2LnFeNb4O15 “tetragonal tungsten bronze”: Towards RT composite multiferroics
Solid State Sciences, 2009
Several Niobium oxides of formula Ba 2 LnFeNb 4 O 15 (Ln = La, Pr, Nd, Sm, Eu, Gd) with the "Tetragonal Tungsten Bronze" (TTB) structure have been synthesised by conventional solid-state methods. The Neodymium, Samarium and Europium compounds are ferroelectric with Curie temperature ranging from 320 to 440K. The Praseodymium and Gadolinium compounds behave as relaxors below 170 and 300 K respectively. The Praseodymium, Neodymium, Samarium, Europium and Gadolinium compounds exhibit magnetic hysteresis loops at room temperature originating from traces of a barium ferrite secondary phase. The presence of both ferroelectric and magnetic hysteresis loops at room temperature allows considering these materials as composites multiferroic. Based on crystalchemical analysis we propose some relationships between the introduction of Ln 3+ ions in the TTB framework and the chemical, structural and physical properties of these materials.
Chemistry of Materials, 2004
Nine tungsten bronze oxides, A 6 M 2 M′ 8 O 30 (A ) Sr 2+ , Ba 2+ , or Pb 2+ ; M ) Ti 4+ , Zr 4+ , or Hf 4+ ; M′ ) Nb 5+ or Ta 5+ ), have been synthesized and characterized. Although structurally very similar, the nine materials are not isostructural. The materials crystallize in noncentrosymmetric space groups, exhibit second-order nonlinear optical behavior, i.e., second-harmonic generation (SHG), by frequency doubling 1064 nm radiation to 532 nm. The SHG efficiencies range from 10 to 600 × SiO 2 . The reported materials are also ferroelectric, as demonstrated by hysteresis loops (polarization vs electric field). Spontaneous polarization values (P s ) range from 0.79 to 12.1 µC/cm 2 . The magnitude of the SHG efficiency and ferroelectric polarization are strongly dependent on the A, M, and M′ cations.
Synthetic Metals, 2005
Transparent glasses in the system (100 − 3x)(Li 2 O-4B 2 O 3 )-x(SrO-Bi 2 O 3 -0.7Nb 2 O 5 -0.3V 2 O 5 ) (where x = 10, 30 and 50, in molar ratio) embedded with nanocrystallites of SrBi 2 (Nb 0.7 V 0.3 ) 2 O 9 exhibited intense second harmonic signals in transmission mode when exposed to IR laser light at λ = 1064 nm. The second harmonic waves were found to undergo optical diffraction. The origin of optical diffraction in these samples was attributed to the self organised structures of fine crystallites of submicrometer size that were inscribed in-situ by the IR laser radiation. Laser Raman studies confirmed these crystallites to be vanadium doped strontium bismuth niobate.
IEEE Journal of Quantum Electronics, 1999
We describe experiments characterizing a new nonlinear optical crystal, YCa 4 O(BO 3 ) 3 (YCOB). This crystal has a number of advantages over other commonly available nonlinear optical crystals. It has a higher nonlinear coefficient than KDP, can be fabricated to large sizes (3-in diameter, 8-in length), and has a high damage threshold. Moreover, this new nonlinear optical crystal is nonhygroscopic, has good optical quality and mechanical properties, allowing easy optical polishing. This crystal, YCa4O(BO3)3, commonly termed YCOB, is one of a family of new nonlinear crystals, the oxyborates, that include RECa4O(BO3)3 (RE=La 3+ , Lu 3+ , Y 3+ , Sm 3+ , Gd 3+ , Er 3+ , and Nd 3+ ). In this paper, we also successfully demonstrate a technique for improving the nonlinear optical properties of this crystal. This technique, ion subsitution, has hetertofore had limited success with other crystal hosts. However, the inclusion of yttrium in YCOB provides the opportunity to exploit this technique. Yb 3+ , which has larger mass, but approximately the same atomic size as Y 3+ , can be substituted into the crystal structure without introducing stress and nonuniformities. A systematic investigation of the linear and nonlinear characteristics of several crystals doped with various levels of Yb demonstrate that selective substitution of Yb in YCa 4 O(BO 3 ) 3 improves the second-harmonic conversion efficiency by increasing the optical nonlinearity. Index Terms-Frequency conversion, nonlinear optical materials, nonlinear optics, rare-earth-doped materials, secondharmonic generation, YCa 4 O(BO 3 ) 3 .
Single crystal growth of the tetragonal tungsten bronze CaxBa1−xNb2O6 (x=0.28; CBN-28)
Journal of Crystal Growth, 2002
The material group of the tetragonal tungsten bronzes (TTBs) is very attractive due to its outstanding ferroelectric properties. Herein we report attempts to grow single crystals of calcium barium niobate (CBN) that until now was only known as ceramic samples. The single crystal growth of CBN could be realized in two different ways. In a first step a high-temperature tetraborate flux was applied to prepare small crystals for phase analysis. Then, for the first time large single crystals of Ca 0.28 Ba 0.72 Nb 2 O 6 (CBN-28) with dimensions up to 5 cm length were grown by using the Czochralski method. CBN-28 shows a ferroelectric phase transition at about 2801C (detected by dielectric and thermal expansion measurements) that is about 2001C higher than the transition temperature of the widely investigated TTB Sr 0.60 Ba 0.40 Nb 2 O 6 (SBN-60).
Harmonic generation in bismuth triborate (BiB3O6)
Applied Physics B, 2005
We report a study of second-and third-harmonic generation in BiB 3 O 6 (BiBO). The effective nonlinearity, phase-matching angle, acceptance bandwidth, and walk-off are calculated and analyzed within the principal planes of the optical indicatrix. In the experiment, the phase-matched harmonic generation is investigated within the xz and yz planes. Also, the temperature dependence of the noncritical phase matching for laser radiation propagating along the z axis is measured for second-harmonic generation (SHG) at crystal temperatures of 25-265 • C. The corresponding wavelengths of the laser radiation are in the range of 1.16 to 1.34 µm. In addition, SHG of 1342-nm radiation of a q-switched Nd:YVO 4 laser system is investigated for noncritical and critical phase matching. The achieved conversion efficiencies are 59% and 20%, respectively. Besides SHG, third-harmonic generation (THG) of 1064-nm, ns laser pulses is investigated. The measured conversion efficiency is as high as 34%. For THG the properties of BiBO are compared with those of BBO and LBO.
Crystal Research and Technology, 2003
Calcium barium niobate (CBN), also like strontium barium niobate (SBN), belongs to the materials family of partially filled tetragonal tungsten bronzes, which show relaxor-type ferroelectric phase transitions and large electro-optic effects. For the first time, it was possible to grow large single crystals of Ca 0.25 Ba 0.75 Nb 2 O 6 (CBN-25) and CBN-28 by using different growing techniques. The successful single crystal growth allowed to investigate several physical properties of the novel phase. Herein, we report on measurements of differential thermal analysis (DTA), wavelength dispersion of the refractive indices, temperature dependence of the birefringence and light absorption. Additionally, results of the single crystal X-ray structure analysis are presented.
High-Pressure Synthesis of Rare-Earth Borate-Nitrate Crystals for Second Harmonic Generation
The crystals of a novel family of rare-earth borate-nitrate compounds, Ln 7 (BO 3) 3 (NO 3)N 3 O (Ln = Pr, Nd), were grown at high-pressure in KAs flux and their crystal structure was determined. The new type of the crystalline structure consists of parallel chains of Ln 6 octahedra connected by common faces and forming the channels with the NO 3 triangular planar motifs in the center, and isolated OLn 4 tetrahedra separated from each other by N 3 triangular motifs. Each NO 3 triangle is in fact a part of rather unusual (NB 3 O 12) block consisting of 3 distorted BO 4 tetrahedra around central nitrogen atom. Under near-infrared (NIR) (λ ex = 1064 nm) excitation, both compounds revealed a strong signal of second harmonic generation (SHG) at half the excitation wavelength (λ em = 532 nm), which is in agreement with their noncentrosymmetric structure. In addition, a photon up-conversion (UC) emission at λ em = 880 nm was observed for microcrystals of Nd 7 (BO 3) 3 (NO 3)N 3 O, which was assigned to the UC process occurring within the 4f electronic manifold of Nd 3+ ions. The dual-emission (SHG/UC) properties of Nd 7 (BO 3) 3 (NO 3)N 3 O microcrystals, concomitant with the absence of photobleaching, makes them prospective candidates for microscopic probes in biological studies.