Investigations on mode-division multiplexed free-space optical transmission for inter-satellite communication link

Wireless Networks - Inter-satellite data transmission links are very crucial for providing global inter-connectivity. We report designing and investigations on high date rate inter-satellite...     

Design of novel circular lattice photonic crystal fiber suitable for transporting 48 OAM modes

In this paper, we propose and numerically investigate a novel circular lattice photonic crystal fiber (CL-PCF) using controllable GeO2 doped silica, suitable for modes carrying quantized orbital angular momentum (OAM). Large effective index separations between 25 supported vector modes (≥10-4) are confirmed over large bandwidth (C+L bands) leading to 48 OAM modes bearing information. The simulations show that the modes in the proposed CL-PCF have good features including low and flat dispersion (within 51.82 ps/km/nm), low confinement loss (lower than 0.002 dB/m), high effective mode area (88.5 μm2) and low nonlinearity (1.22 W-1.km-1). These promising results show that the proposed CL-PCF could be an arguably candidate in fiber-based OAM multiplexing or other applications using OAM states.     

Structural and spectroscopic investigation of the N-methylformamide–water (NMF···3H2O) complex

In this work, theoretical studies on the structure, molecular properties, hydrogen bonding, and vibrational spectra of the N-methylformamide–water (NMF···3H₂O) complex will be presented. The molecular geometry was optimised by using Hartree–Fock (HF), second Møller–Plesset (MP2), and density functional theory methods with different basis sets. The harmonic vibrational frequencies are computed by using the B3LYP method with 6-311++G(d,p) as a basis set and then scaled with a suitable scale factor to yield good coherence with the observed values. The temperature dependence of various thermodynamic functions (heat capacity, entropy, and enthalpy changes) was also studied. A detailed analysis of the nature of the hydrogen bonding, using natural bond orbital (NBO) and topological atoms in molecules theory, has been reported.     

Decarboxylation,during their aromatization by Pd/C,of some 3,4-octahydronaphtho-7,8-benzocoumarins : Synthesis of 1,2'-binaphthyls and 2,2'-binaphthyls

Some 3',4'-cyclohexa-1',2'-dihydro- and 1',2'-cyclohexa-3',4'-dihydro-3,4,7,8-dibenzocoumarins 2 and 3 were prepared by catalytic condensation between a naphthol and a α-carbethoxy-cis- decalone (?1 or ?2). These compounds, when treated with Pd/C at 260°, undergo, beside aromatization, a complete decarboxylation of the lactone ring. A mechanism, involving H transfer through a π-allylic palladium complex is described.