Extractable energy from erbium-ytterbium co-doped pulsed fiber amplifiers and lasers

An analytic model is developed for evaluating the extractable energy from high energy pulsed erbium-ytterbium co-doped fiber amplifiers and lasers. The energy extraction capabilities under the limitation of spurious lasing, due to amplified spontaneous emission (ASE), are mapped for various numerical apertures, single and multi transverse mode evolution and operating wavelengths. The model provides an assessment for the maximum pulse energy that can be extracted from a given erbium-ytterbium co-doped fiber. In addition, the model can be used to determine the repetition rate and optimal length, under which the laser source will be optimally operated in order to achieve a required extracted energy, without spurious lasing. The results show a clear advantage in using 915 nm wavelength pump source over 975 nm, at high average power operation, due to augmented 1 μm ASE at 975 nm pump wavelength, as a result of the Yb³⁺ population inversion.     

From Intersectors to Successors

 A geometric graph any two line segments of which intersect is called an intersector. This notion will be generalized in order to obtain new results which are not true for this (restricted) category. Received: December 8, 1997 Final version received: January 12, 2000     

Optimal control of the transverse vibrations of a beam with a bound on the potential energy

The problem of the optimal control of the transverse vibrations of a uniform beam with a bound on the potential energy is considered. Approximation theory is used. It is shown that the optimal control exists, and a simple method for its computation is suggested.     

Entanglement generation of nearly random operators

We study the entanglement generation of operators whose statistical properties approach those of random matrices but are restricted in some way. These include interpolating ensemble matrices, where the interval of the independent random parameters are restricted, pseudorandom operators, where there are far fewer random parameters than required for random matrices, and quantum chaotic evolution. Restricting randomness in different ways allows us to probe connections between entanglement and randomness. We comment on which properties affect entanglement generation and discuss ways of efficiently producing random states on a quantum computer.