Passively mode-locked glass waveguide laser with 14-fs timing jitter

Ultralow jitter pulse trains are produced from a passively mode-locked, erbium/ytterbium co-doped, planar waveguide laser by use of high-bandwidth feedback control acting on the physical cavity length and optical pump power. Synchronization of a 750-MHz, fundamentally mode-locked laser to an external clock signal yields an ultralow, root-mean-square relative timing jitter of 14.4 fs integrated from 10 Hz to the Nyquist frequency of 375 MHz.     

Single-electron transistor spectroscopy of InGaAs self-assembled quantum dots

A single-electron transistor (SET) is used to detect tunneling of single electrons into individual InGaAs self-assembled quantum dots (QDs). By using an SET with a small island area and growing QDs with a low density we are able to distinguish and measure three QDs. The bias voltage at which resonant tunneling into the dots occurs can be shifted using a surface gate electrode. From the applied voltages at which we observe electrons tunneling, we are able to measure the electron addition energies of three QDs.     

Effect of Detachments in Asymmetric Simple Exclusion Processes

Asymmetric simple exclusion processes are important for understanding low-dimensional multi-particle dynamic phenomena. The effect of irreversible detachments of particles on dynamics of asymmetric simple exclusion processes is studied using analytical and computer simulation techniques. In the simplest model, where particles can only detach from a single site in the bulk of the system, a theory is presented and used to calculate explicitly phase diagrams and particle density profiles. The complexity of the phase behavior is discussed in terms of a recent domain-wall theory for driven lattice systems. The theoretical results qualitatively and quantitatively agree with computer Monte Carlo simulations.     

Comparison of stress-controlled and strain-controlled rheometers for large amplitude oscillatory shear

In linear viscoelastic region, it is well known that dynamic modulus and dynamic compliance can be converted to each other. However, it is questionable whether there exists an interconversion between large amplitude oscillatory shear (LAOS) data measured from different types of rheometers—stress-controlled and strain-controlled rheometers. Hence, we tried to prove the existence by use of polyethylene oxide (PEO) aqueous solutions with well-developed entanglements. From this experiment, we can conclude that a stress-controlled rheometer can simulate LAOS behavior measured from a strain-controlled rheometer under the conditions where inertia effect is not significant. Furthermore, it is investigated whether the LAOS data of the stress-controlled rheometer obey stress–frequency superposition as the strain–frequency superposition found by Cho et al. (J Rheol 54:27–63, 2010) from LAOS data measured by the strain-controlled rheometer. This scaling relation shows that the dimensionless stress amplitude is a function of zeta which is the product of the stress amplitude and linear viscoelastic function J′(ω). The plot shows that all of the data are superposed in a single curve without regard to frequency, molecular weight, and concentration of PEO aqueous solutions.     

Fabrication and characteristics of double-fused vertical-cavity lasers

We discuss the fabrication process and characteristics of three consecutive runs of double-fused 1.5-m vertical-cavity lasers. We have measured light-current characteristics of over three hundred lasers with ten different diameters between 6 and 60 m and observe a yield of over 95%. The process and design improvements resulted in a low pulsed threshold current of 3 mA on a number of 6- and 8-m-diameter devices and threshold current density of 2 kA cm^–2 on 60-m-diameter devices at room temperature.     

Fano resonances in planar silver nanosphere clusters

The plasmonic properties of silver nanosphere clusters are investigated using the finite element and the plasmon hybridization methods. The nanoparticle clusters are found to exhibit multiple plasmon resonances with large induced electromagnetic field enhancements. For symmetric clusters, we show how group theory can be used to identify the microscopic nature of the plasmon resonances. For larger clusters, we show that narrow Fano resonances are frequently present in their optical spectra.     

Plasmon modes of nanosphere trimers and quadrumers

Using the plasmon hybridization method, we investigate the plasmon frequencies and optical absorption spectra of symmetric configurations of nanosphere trimers and quadrumers. Plasmon hybridization allows us to express the fundamental plasmon modes of these multinanosphere systems as linear combinations of the plasmons of individual nanospheres in a manner analogous to molecular orbital theory. We show how group theory may be used to interpret the plasmon modes of each multiparticle system as specific structure-dependent symmetric combinations of the plasmon modes of the individual nanoparticles. We compare the optical absorption spectra calculated using plasmon hybridization with the spectra obtained using finite difference time domain simulations.