Experimental confirmation has been made on a driven relaxation oscillator circuit, first presented by Van der Pol, of the periodadding route to chaos. The nonlinear element in the circuit is a neon bulb, modeled by a three-segment piecewise-linear current-controlled resistor. A simple nonlinear circuit model has been used to reproduce in simulations the experimentally-observed period-adding phenomenon.

Non-interpenetrating two star polymer catalysts designed to mimic the site isolation characteristics of enzymes enabled a one-pot asymmetric cascade reaction. Thus, the one-pot nucleophilic addition of 2 to 1 and Michael addition of the resulting 3 to 4 were performed with a star polymer salt catalyst 6˙7 (20 mol%) [prepared from an acidic star polymer 6 and imidazolidinone (S,S)-7], a pyrrolidine star polymer (S)-8 (20 mol%), and a catechol mediator 9 (1 mol equiv) to give ( R,S )-5 in 89% yield with >99% ee and 96% de. The use of 10 or 11 in place of 6 or 8 under similar conditions did not give 5.

A statistical approach is taken toward the ray optics of optical media with complicated nonspherical and nonplanar surface shapes. As a general rule, the light in such a medium will tend to be randomized in direction and of 2n2(x) times greater intensity than the externally incident light, where n(x) is the local index of refraction. A specific method for doing optical calculations in statistical ray optics will be outlined. These optical enhancement effects can result in a new type of antireflection coating. In addition, these effects can improve the efficiency as well as reduce the cost of solar cells.

Two different bifurcation patterns are experimentally observed in Chua's circuit. They show that antimonotonicity — inevitable reversals of period-doubling sequences, is a typical phenomenon in Chua's circuit.

Surface recombination is an important characteristic of an optoelectronic material. Although surface recombination is a limiting factor for very small devices it has not been studied intensively. We have investigated surface recombination velocity on the exposed surfaces of the AlGaN, InGaAs, and InGaAlP material systems by using absolute photoluminescence quantum efficiency measurements. Two of these three material systems have low enough surface recombination velocity to be usable in nanoscale photonic crystal light-emitting diodes.

A nonoxide surface passivation for crystalline silicon is described. It involves the fluorination of the silicon surface. Characterization by photoconductive lifetime measurements and C–V measurements on MIS structures indicate that the fluorinated silicon surface is extraordinarily electrically passive, ≲1010 traps per cm2. Our technique for producing such high quality surfaces is described as is a novel gate insulator structure employing organic thin films. Potential device advantages of this alternative to oxide technology are also discussed.

We describe how quantum information may be transferred from photon polarization to electron spin in a semiconductor device. The transfer of quantum information relies on selection rules for optical transitions, such that two superposed photon polarizations excite two superposed spin states. Entanglement of the electron spin state with the spin state of the remaining hole is prevented by using a single, non-degenerate initial valence band. The degeneracy of the valence band is lifted by the combination of strain and a static magnetic field. We give a detailed description of a semiconductor structure that transfers photon polarization to electron spin coherently, and allows electron spins to be stored and to be made available for quantum information processing.

Antenna arrays on conventional ground planes present different deficiencies. For compact platforms, the propagation of RF surface currents results in lost power, radiation from the edges and other discontinuities. It also contributes to the strong coupling and causes blind angles and multipath interference. By building radio isolation into the ground plane of phased array antenna structures, it is possible to reduce these different disturbances. This isolation may be achieved by using corrugated surfaces. In this case, DC currents are conducted but not AC currents. Based on the previous work done on PBG structure, a new kind of surface called High Impedance Ground Plane can be used. This kind of ground plane presents the same characteristics are corrugated surfaces in all the directions. Moreover the thickness must no longer be one fourth of the wavelength and can be even much smaller. These ground planes have been applied antenna array in order to reduce the disturbances created on compact platforms. Phase measurements of two-dipole array clearly shows this reduction.

For maximal performance solar cells should resemble semiconductor lasers, i.e., they should be constructed in the form of a double heterostructure. We have found rather good performance in SIPOS-crystalline silicon-SIPOS double heterostructure solar cells, where SIPOS≡SiOx. The processing of these solar cells gives insights into the truly outstanding performance of the n+-SIPOS: p-Si heterojunction which has a forward saturation current coefficient J0=10−14 A/cm2, or equivalently an ‘‘emitter Gummel number’’ Ge=3.3×1015 s/cm4. This suggests that crystalline silicon solar cells can be much more efficient than had been suspected.

The Internet has created a boom in long-distance optical communications. Web surfers click away and download ever-larger files, oblivious to their distance from a Web host. As a result the demand for capacity in undersea optical-fibre communications is escalating. A simple way to increase the capacity is to send many separate optical wavelengths through the same fibre, a technique known as wavelength division multiplexing. However, there is a limit to the optical power that can be used to send information along a fibre, and this – rather than the bandwidth of the fibre, which is prodigious – limits the capacity of optical fibres to carry information.