Doris Ehrt

X-ray induced effects in phosphate glasses

Abstract Optical absorption and paramagnetic resonance spectra of X-ray irradiated (λCuKα=0.154 nm) ultra- and metaphosphate glasses of high purity were studied. Melting of the samples under different redox conditions, investigation of annealing behavior of the irradiated samples and correlation between optical and EPR spectra allowed the resolution of five main paramagnetic radiation-induced defects and associated optical absorption bands. Phosphorus and oxygen related radiation-induced defects were found, with hole centers POHC and OHC absorbing in the visible and electron trapped centers PO2, PO3 and PO4 absorbing in the ultraviolet region.

Fluoroaluminate glasses for lasers and amplifiers

Abstract Fluoroaluminates are well known glass formers. Although their glass forming ability is low, it can be increased by doping with phosphates. Structure and properties depend mainly on the fluoride to phosphate ratio. In this review a number of recent developments in the use of these glasses for the fabrication of active laser and amplifier materials is discussed.

Scaling laser-diode pumped solid-state amplifiers to the petawatt level

Summary form only given. Increased performance of high-power laser-diodes, decline in laser-diode-power cost, development of new lasing materials, progress on key optical components, and novel pulse-compression techniques enable the design of efficient petawatt-class amplifiers based on diode-pumped chirped-pulse amplification technology. New research in high-field plasma physics, laser-pumped X-ray sources, laser fusion, particle accelerators and generators, as well as astro-physics is envisioned. We have developed laser-diode bars for long pulse pumping that deliver more than 200 W peak-power at almost 50% electrical to optical efficiency. Progress in semiconductor technology, heat-sink design, and diode packaging ensures safe pulsed operation for the required lifetime at driving currents of more than 220 A.. The system design of POLARIS (Petawatt Optical Laser Amplifier for Radiation Intensive Experiments) and supporting data is presented, and the prospects and scaleability of diode-pumped high-power laser-technology discussed. The front-end consisting of a Ti:sapphire oscillator, a low-aberration stretcher, and a regenerative amplifier delivers 1 mJ in 2 ns pulses with 14 nm band width centered at 1035 nm.

POLARIS - A compact, diode-pumped laser system in the Petawatt regime

POLARIS is a compact diode pumped Yb-phosphate glass laser system. It is designed to reach the petawatt regime with a possible repetition frequency of 0.1 Hz. The first three amplifiers of this system are operating, and already constitute an all diode pumped terawatt system. The POLARIS system is designed to have an output of about 150 J in 150 fs, and should be completed in 2006.