Longitudinal spatial hole burning and associated nonlinear gain in gain-clamped semiconductor optical amplifiers

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Nonlinear, kinetic simulations of stimulated Raman scattering (SRS) under laser-fusion conditions present a bursting behavior. Different explanations for this regime have been given in previous studies: saturation of SRS by increased nonlinear Landau damping [K. Estabrook et al., Phys. Fluids B 1, 1282 (1989)], and detuning due to the nonlinear frequency shift of the plasma wave [H. X. Vu et al., Phys. Rev. Lett. 86, 4306 (2001)]. Another mechanism, also assigning a key role to the trapped electrons is prop

The ring cyclotron of the Paul Scherrer Institute (PSI) accelerates an intense proton beam from 72MeV up to 590MeV. This happens in four cavities of very high quality factor, oscillating in the fundamental mode. The beam can excite parasitic oscillation modes (HOMs), because of its time structure. Measurements showed that their field can leak out into the vacuum chamber. Until now, there is no tool available to predict the potentially harmful effect of these HOMs onto the beam operation of the cyclotron. It

Route guidance refers to information provided to travelers in an attempt to facilitate their decisions relative to departure time, travel mode and route. We are specifically interested in consistent anticipatory route guidance, in which real-time traffic measurements are used to make short-term predictions, involving complex simulation tools, of future traffic conditions. These predictions are the basis of the guidance information that is provided to users. By consistent, we mean that the anticipated traffi

We report a novel three-contact coupled-vertical-cavity surface-emitting laser (VCSEL) for use in polarization-sensitive optical applications. The device consists in two vertical cavities, coupled by a common semitransparent mirror. We demonstrate that one can independently choose both the power of the output beam - through the current in the first cavity - and the polarization state - through the bias applied to the second cavity. The control of the polarization state is performed with a control of voltage

We report, to our knowledge, the first active channel waveguide in Ti:sapphire. We have created [similar to] 1.4-μm high ribs in a [similar to] 10-μm thick Ti:sapphire planar waveguide by reactive ion etching. Following excitation by an Ar-ion laser, the rib structure showed channel-waveguide fluorescence emission. The mode profiles and the beam-parameter values (M2) were measured. The coupling efficiency of fluorescence emission into a single-mode fiber was an order of magnitude higher than for fluorescenc

The Laboratory of Electrical Machines of the Swiss Federal Institute of Technology (Lausanne) has developed a software (TLSim) for the simulation of electrical urban transportation systems. This program can simulate the behaviour of the power supply network (current and voltage level at any point of the topology) comprising uni- and bi- directionnal sub-stations. In the network the vehicules (trolleybus) may run along any defined path through different electrical supply sectors. Several models of trolleybus

Two Mach-Zehnder interferometers (MZI), one with Y-junction-couplers and the other with multimode interference (MMI), were presented. Both MZI were developed in silicon-on-insulator (SOI) technology and used plasma dispersion effect for light phase modulation. Fiber-to-fiber insertion losses, absorption coefficients, optical coefficients modulated intensities as function of time and modulation extinction ratios versus signal frequencies were measured for these devices at various wavelengths. Both devices we

Flexible AC Transmission Systems (FACTS) are systems based on power electronics using GTO or IGCT semiconductors [1] that allow a better use of the transfer capacities of the transmission lines and permit to satisfy the requirements due to the liberalization of the electrical energy market. The Unified Power Flow Controller (UPFC) is one of the most versatile topologies of the FACTS family. The UPFC can be decomposed in two different power circuits: the parallel one maintaining the network bus voltage by co

The E-J power law as electric characterization of the HTS material in Finite Element computations has shown good agreement with measurements of field-dependent crtical current density and losses due to transport current. We use this technique to investigate the loss caused by Ac transport current in self-field and in applied AC magnetic field in both elliptical monocore and multicore tapes, where the current is generated by means of a voltage source. The current density is first kept constant and then varie

This paper examines the use of thyristor controlled series capacitors (TCSCs) for the redistribution of active power flows (PFs) in a transmission network and presents a simple model of a hierarchical coordinated control system for multiple devices. The TCSC is one of the representatives of the flexible AC transmission system (FACTS) devices family and is a solid-state converter that has the capability of controlling PFs in transmission lines by changing its reactance. The model is based on a sensitivity an

We present the design of a highly efficient, pulsed ammonia laser which is optically pumped by a commercial TEA CO2 laser and is line tunable in the spectral range of 780-930 cm(-1). The power, spectral, and temporal characteristics of the laser have been investigated for different configurations of the optical cavity. Using a stable resonator, the laser operates with an efficiency of 24% (940 mJ) in a multiline configuration and 16.5% on a single line. Changing the resonator to an unstable configuration pr

Theoretical and experimental work on the vertical position control system on the COMPASS-D tokamak is described. An analog proportional + derivative (P + D) system is currently used, and two important sources of disturbance are observed in the system. One source is 600-Hz noise from thyristor power supplies, and the other is impulselike disturbances due to edge-localized modes (ELMs). A high-order controller is developed using the H-infinity technique to reduce the effect of the 600-Hz noise. This initial d

Longitudinal spatial hole burning and associated nonlinear gain in gain-clamped semiconductor optical amplifiers

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Trapped-particle instability leading to bursting in stimulated Raman scattering simulations

Beam-cavity interactions in high power cyclotrons

Solving the anticipatory route guidance generation problem using a generalization of secant methods

Investigation of polarization behavior in a vertical coupled-cavities surface-emitting laser

Ti:sapphire rib channel waveguide fabricated by reactive ion etching of a planar waveguide

TLSim: A software for Electrical Public Transportation Systems

Intensity modulation in two Mach-Zehnder interferometers using plasma dispersion in silicon-on-insulator

Investigation of the 3-Level Unified Power Flow Controller (UPFC)

Losses in HTS Tapes due to AC External Magnetic Field and AC Transport Current

Coordinated control of multiple series FACTS devices

Highly efficient optically pumped NH3 laser with near diffraction limited output

Vertical position control on COMPASS-D