Analysis of Birefringence Compensation Using a Quarter-Wave Plate in Solid-State Lasers

Using Jones matrix formulation, the theoretical calculations of birefringence compensation technique for a quarter-wave plate scheme are presented. This scheme was proposed and experimentally demonstrated by W. A. Clarkson et al. (Opt. Lett. 24 (1999) 820). In the present paper we have theoretically confirmed that using this method, even in principle, complete compensation is not possible. However, it is shown quantitatively that this scheme does makes possible effective compensation for the birefringence in as few as several tens of watts of pumping power region, which is an attractive feature for laser-diode (LD) pumped solid-state laser systems. We also found good agreement between our theoretical calculations and experimental results obtained by W. A. Clarkson et al. For example, from the analysis we show that only < 0.1% loss will be generated by about 10 W of heat deposited in the rod. This corresponds to about 30 W of LD pump power, which may generate from 6 to 10 W output power depending upon the conversion efficiency of type lasers     

Composition of matrix products and categorical equivalence

First, we prove two finite algebras are categorically equivalent if and only if the matrix products of their irredundant non-refinable covers are isomorphic. Second, we characterize families of irreducible algebras such that there exists an algebra whose neighbourhoods in an irredundant non-refinable cover are isomorphic to the respective irreducible algebra in the given family. Finally, we exhibit two facts by constructing examples. The first one is that there is a family of irreducible algebras such that there are many algebraic structures whose neighbourhoods in an irredundant non-refinable cover are isomorphic to the respective irreducible algebra in the given family. The second example is an algebra such that the matrix product of an irredundant non-refinable cover is bigger than the given algebra.     

Oriented and low‐density tin dioxide film by sol–gel mineralizing tin‐contained hydroxypropyl cellulose lyotropic liquid crystal for laser‐induced extreme ultraviolet emission

A series of tin‐doped hydroxypropyl cellulose (HPC) lyotropic liquid crystal (LC) was synthesized using a simple process and their properties were characterized using selective reflection, wide‐angle X‐ray diffraction (WAXD), and the band texture observed under polarized optical microscope. The present preparation is applicable for mass production using large substrate with low cost HPC. A cholesteric lyotropic LC phase was observed for the hybrid solution with higher than 40 wt % HPC. After sol–gel condensation, the HPC‐Sn hybrid LC films were calcined at 400 °C and the as‐prepared product was determined to obtain tin dioxide (SnO₂) which was characterized using WAXD. The iridescent color and ～2 nm structure seen after the condensation disappeared in the as‐prepared SnO₂. Scanning electronic microscope images of the SnO₂ showed that the HPC content in the HPC‐Sn hybrid played an important role in controlling the SnO₂ morphology. A spectrum of relatively monochromatic extreme ultraviolet (13.5 nm) emission was measured in the as‐prepared SnO₂ in comparison with bulk tin and inverse opal SnO₂. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4566–4576, 2009     

Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.     

Formation and properties of n-alkylammonium complexes with layered tri- and tetra-titanates

The formation of n-alkylammonium complexes was studied using Na₂Ti₃O₇ and K₂Ti₄O₉ and the results for both compounds were compared. Alkylammonium complexes could be obtained from H₂Ti₃O₇ and H₂Ti₄O₉·H₂O, which were prepared by HCl treatment of Na₂Ti₃O₇ and K₂Ti₄O₉ respectivel The complexes were formed by exchange of H⁺ with alkylammonium ions. Molecular intercalation of alkylamine was also possible with H₂Ti₄O₉·H₂O. However, alkylammonium complexes were not formed directly from Na₂Ti₃O₇ and from K₂Ti₄O₉. Orientations of alkylammonium ions in the interlayer are also discussed in relation to the structure of the titanate layers.     

The matrix effect on stereoselectivity of olefin cyclopropanation by arylcarbene

Temperature studies of additon of phenylcarbene to styrene showed that stereoselectivity changed rather dramatically as the reaction phase changed.     

Giant Nernst effect in CeCoIn5

We present a study of Nernst and Seebeck coefficients of the heavy-fermion superconductor CeCoIn5. Below 18 K, concomitant with a field-dependent Seebeck coefficient, a large sublinear Nernst signal emerges with a magnitude drastically exceeding what is expected for a multiband Fermi-liquid metal. In the mixed state, in contrast with all other superconductors studied before, this signal overwhelms the one associated with the motion of superconducting vortices. The results point to a hitherto unknown source of transverse thermoelectricity in strongly interacting electrons.     

Twofold spontaneous symmetry breaking in the heavy-fermion superconductor UPt3

The field-orientation dependent thermal conductivity of the heavy-fermion superconductor UPt3 was measured down to very low temperatures and under magnetic fields throughout the distinct superconducting phases: B and C phases. In the C phase, a striking twofold oscillation of the thermal conductivity within the basal plane is resolved reflecting the superconducting gap structure with a line of node along the a axis. Moreover, we find an abrupt vanishing of the oscillation across a transition to the B phase, as a clear indication of a change of gap symmetries. We also identify extra two line nodes below and above the equator in both B and C phases. From these results together with the symmetry consideration, the gap function of UPt3 is determined as a E(1u) representation characterized by a combination of two line nodes at the tropics and point nodes at the poles.