Phase-matched frequency doubling in a LiNbO3-sapphire waveguide

An rf-sputtered thin film of LiNbO₃ on a sapphire substrate was used as a waveguide for optical frequency doubling. Employing a Nd:YAG laser and a tunable dye laser, whose output was used to pump a stimulated Raman cell, the TM^ω₀→TM^2W₂ up-conversion process was investigated in detail and the phase matched nature of this process was demonstrated. The conversion efficiency was estimated to be about 10^?3.     

Crystal structure of 3β-acetoxy-pregna-5,16-dien-20-one (16 DPA)

The title compound, 3β-acetoxy-pregna-5,16-dien-20-one, C₂₃H₃₂O₃, has been synthesized by acetylation followed by oxidation of diosgenin and its crystal structure has been solved from single crystal X-ray diffraction data. The compound crystallizes into orthorhombic space group P2₁2₁2₁ with unit cell parameters: a = 6.031(4) ?, b = 12.481(2) ?, c = 27.162(5) ?, Z = 4. The crystal structure has been refined to R = 0.0597 for 1291 observed reflections. Rings A and C of the compound are in chair conformation whereas ring B is in half-chair conformation. Ring D is in envelop conformation. The A/B ring junction is quasi-trans, while ring systems B/C and C/D are trans fused about the C8–C9 and C13–C14 bonds, respectively. The steroid nucleus has a small twist, as shown by the C19–C10⋅C13–C18 pseudo-torsion angle of 9.5°. The crystal packing is determined by a pair of weak C–H⋅O hydrogen bonds in addition to van der Waals interactions.     

Trigonometric approximation of functions in $$L_1$$ L 1 -norm

Periodica Mathematica Hungarica - In this paper, the authors have obtained $$L_1$$ -approximations of functions f in $$ {{\,\mathrm{Lip}\,}}(\alpha ,1) $$ $$ (0 < \alpha \le 1) $$ by...