Record bandwidth and sub-picosecond pulses from a monolithically integrated mode-locked quantum well ring laser.

In this paper, we present the detailed characterization of a semiconductor ring passively mode-locked laser with a 20 GHz repetition rate that was realized as an indium phosphide based photonic integrated circuit (PIC). Various dynamical regimes as a function of operating conditions were explored in the spectral and time domain. A record bandwidth of the optical coherent comb from a quantum well based device of 11.

High-efficiency dielectrophoretic ratchet.

Brownian ratchets enable the use of thermal motion in performing useful work. They typically employ spatial asymmetry to rectify nondirected external forces that drive the system out of equilibrium (cf. running marbles on a shaking washboard).

A low-power high-speed InP microdisk modulator heterogeneously integrated on a SOI waveguide.

We report on the modulation characteristics of indium phosphide (InP) based microdisks heterogeneously integrated on a silicon-on-insulator (SOI) waveguide. We present static extinction ratios and dynamic operation up to 10 Gb/s. Operation with a bit-error rate below 1 × 10(-9) is demonstrated at 2.

Organic electronic ratchets doing work.

The possibility to extract work from periodic, undirected forces has intrigued scientists for over a century—in particular, the rectification of undirected motion of particles by ratchet potentials, which are periodic but asymmetric functions. Introduced by Smoluchowski and Feynman to study the (dis)ability to generate motion from an equilibrium situation, ratchets operate out of equilibrium, where the second law of thermodynamics no longer applies. Although ratchet systems have been both identified in nature and used in the laboratory for the directed motion of microscopic objects, electronic ratchets have been of limited use, as they typically operate at cryogenic temperatures and generate subnanoampere currents and submillivolt voltages.

Real versus measured surface potentials in scanning Kelvin probe microscopy.

Noncontact potentiometry or scanning Kelvin probe microscopy (SKPM) is a widely used technique to study charge injection and transport in (in)organic devices by measuring a laterally resolved local potential. This technique suffers from the significant drawback that experimentally obtained curves do not generally reflect the true potential profile in the device due to nonlocal coupling between the probing tip and the device. In this work, we quantitatively explain the experimental SKPM response and by doing so directly link theoretical device models to real observables.

A fast low-power optical memory based on coupled micro-ring lasers.

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers.