All fiber-optic neural network using coupled SOA based ring lasers.

An all-optical neural network is presented that is based on coupled lasers. Each laser in the network lases at a distinct wavelength, representing one neuron. The network status is determined by the wavelength of the network's light output.

Carrier recovery time in semiconductor optical amplifiers that employ holding beams.

An analytical expression for the carrier recovery time in semiconductor optical amplifiers (SOAs) that employ holding beams is presented. The amplifier model from which the expression is derived assumes a uniform carrier density along the SOA's length and that the signal and the holding beams both receive amplification. Simulations and experiments show that the expression predicts the recovery time well over a wide range of amplifier gains, holding beam powers, and configurations.

An optical threshold function based on polarization rotation in a single semiconductor optical amplifier.

Optical threshold functions are a basic building block for all-optical signal processing, and this paper investigates a threshold function design reliant on a single active element. An optical threshold function based on nonlinear polarization rotation in a single semiconductor optical amplifier is proposed. It functions due to an induced modification of the birefringence of a semiconductor optical amplifier caused by an externally injected optical control signal.

All-optical demultiplexing of 640 to 40 Gbits/s using filtered chirp of a semiconductor optical amplifier.

We present a high-capacity ultrafast all-optical time demultiplexer that can be employed to retrieve 40 gigabits/second (Gb/s) base-rate channels from a 640 Gb/s single-polarized signal. The demultiplexer utilizes ultrafast effects of filtered chirp of a semiconductor optical amplifier. Excellent demultiplexing performance is shown at very low switching powers: +8 dBm (640 Gb/s data) and -14 dBm (40 GHz clock).

Optical shift register based on an optical flip-flop memory with a single active element.

We present an optical shift register that consist out of two serially connected optical flip-flop memories driven by common clock pulses. Each optical flip-flop consists out of two ring lasers sharing a single active element, which makes the optical flip-flops easily cascade with each other. The two cascaded optical flip-flops are controlled by the clock pulses in such a way that the input data set the new state of the first optical flipflop, after the state of the first flip-flop has been transferred to the second optical flip-flop.

Coupled Mach-Zehnder interferometer memory element.

Two active Mach-Zehnder interferometers are integrated in a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set-reset flip-flop. The switching time for this initial device is approximately 200 ps.

Interchannel nonlinear transmission penalties in polarization-multiplexed 2 x 10 Gbit/s differential phase-shift keying transmission.

We discuss the performance of a multichannel 2 x 10 Gbit/s polarization-multiplexed differential phase-shift keying transmission system. Through simulations and transmission experiments we find that, despite the constant power envelope of non-return-to-zero phase-shift keying modulation formats, polarization multiplexing strongly reduces the nonlinear tolerance and transmission performance at a 2 x 10 Gbit/s line rate with multichannel transmission. This results in a 10 dB power penalty when comparing single- and nine-channel transmission.

SOA-based all-optical switch with subpicosecond full recovery.

We investigate all-optical switching in a multi-quantum-well semiconductor optical amplifier-based nonlinear polarization switch using optical pulses with duration of 200 fs at a central wavelength of 1520 nm. We show full recovery of the switch within 600 fs, in both the gain and absorption regime. We discuss the switching and recovery mechanisms using numerical simulations that are in qualitatively good agreement with our experimental data.

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.

Mixed data rate and format transmission (40-Gbit/s non-return-to-zero, 40-Gbit/s duobinary, and 10-Gbit/s non-return-to-zero) by mid-link spectral inversion.

A polarization-diverse subsystem based on periodically poled lithium niobate waveguides is used as an optical phase conjugator for compensation for linear and nonlinear distortion. We show successful transmission formats of 13 x 40 Gbit/s non-return-to-zero mixed with 6 x 10 Gbit/s non-return-to-zero and 40-Gbit/s duobinary over 8 x 100 km of standard single-mode fiber. A single phase conjugator is used to conjugate all data formats, including the alternative duobinary format, simultaneously.

Sub-picosecond pulse generation employing an SOA-based nonlinear polarization switch in a ring cavity.

We demonstrate the generation of sub-picosecond optical pulses using a semiconductor optical amplifier (SOA) and a linear polarizer placed in a ring-laser configuration. Nonlinear polarization rotation in the SOA serves as the passive mode-locking mechanism. The ring cavity generates pulses with duration below 800 fs (FWHM) at a repetition rate of 14 MHz.

Adsorption of sodium lauryl sulfate onto arsenic-bearing ferrihydrite.

Ferrihydrite is an excellent adsorbent for binding trace toxic contaminants such as arsenic, and precipitate flotation of the arsenic-bearing ferrihydrite has been studied. Anionic surfactants such as sodium lauryl sulfate (SLS) and sodium oleate (NaOL) are suitable collectors for the flotation. The adsorption of SLS both alone and after the subsequent addition of NaOL on these precipitates at pH 4-5 was measured.

Photochemical oxidation of arsenic by oxygen and iron in acidic solutions.

The rate of oxidation of As(III) to As(V) by oxygen is increased by several orders of magnitude by the presence of dissolved Fe(III) and illumination with near ultraviolet light. The oxidation reaction has been studied in acidic conditions in the absence and presence of dissolved oxygen. A reaction mechanism has been postulated in which Fe(III)-hydroxide and -chloride complexes first absorb photons to produce highly oxidising hydroxyl and dichloro radicals.

Tamsulosin 0.4 mg once daily: tolerability in older and younger patients with lower urinary tract symptoms suggestive of benign prostatic obstruction (symptomatic BPH). The European Tamsulosin Study Group.

Objectives: To compare the safety and tolerability of tamsulosin 0.4 mg once daily in younger (< 65 years) and older (> or = 65 years) patients with lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction (BPO).

Methods: In a retrospective analysis of two European double-blind, randomized, placebo-controlled trials, safety was assessed in 574 younger or older patients treated with tamsulosin or placebo for 12 weeks.

A new long acting formulation of the luteinizing hormone-releasing hormone analogue goserelin: results of studies in prostate cancer.

Purpose: To assess the pharmacodynamic equivalence of the new 10.8 mg. goserelin depot with the current 3.

Identification, purification, and some physicochemical properties of staphylococcal enterotoxin C3.

A third staphylococcal enterotoxin C (C3) has been identified, purified, and characterized. Staphylococcal enterotoxin C3 was identified from a Staphylococcus aureus isolated received from England. The purified toxin was determined by gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be a simple protein with a molecular weight of 26,900.

Purification and some physicochemical properties of toxic-shock toxin.

A procedure for the purification of a protein marker for the staphylococci isolated from toxic-shock syndrome patients has been developed. The purification procedure involves the removal of the toxic protein from culture supernatant fluids of toxic-shock syndrome associated Staphylococcus aureus strains FRI-1169 and FRI-1183 by batch absorption with CG-50 resin, ion-exchange chromatography on CM-Sepharose CL-6B, and gel permeation chromatography on Sephacryl S-200. The purified toxin is a simple protein with a molecular weight of 24 000 +/- 500 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Optical fiber end preparation: a new method for producing perpendicular fractures in glass fibers, coated-glass fibers, and plastic-clad fibers.

A new method for cutting optical fibers is presented. A smooth scratch, without any visible cracks and chipping, is circumferentially made around the complete periphery before the fiber is fractured by simple axial tension. Break angles of 0.