Parametric frequency conversion of coherent light by the electro-optic effect in KDP

We report an experiment in which interaction between an optical wave at frequency f0 and a microwave signal at fm was used to generate a coherent optical beam at f0 + fm. The interaction was provided by lossless electro-optic modulation of the dielectric constant within a laser resonator and can thus be viewed as a demonstration of parametric(3-5) interaction at optical frequencies

Interferometry and Laser Control with Solid Fabry-Perot Etalons

The use and analysis of solid Fabry-Perot etalons for interferometry and laser control are discussed and supported with experimental data. Low angle scattering is found to be an important factor influencing finesse and peak transmission. Thermal tuning sensitivity and wedge-angle control with thermal gradients are analyzed and illustrated. Control of laser oscillations using a solid-state etalon as a laser cavity end mirror is discussed. The use of the solid etalon as an optical cavity coupler is applied to the problem. of sideband energy removal from an internally modulated laser

The lightcraft project

Rensselaer Polytechnic Institute has been developing a transatmospheric 'Lightcraft' technology which uses beamed laser energy to propel advanced shuttle craft to orbit. In the past several years, Rensselaer students have analyzed the unique combined-cycle Lightcraft engine, designed a small unmanned Lightcraft Technology Demonstrator, and conceptualized larger manned Lightcraft - to name just a few of the interrelated design projects. The 1990-91 class carried out preliminary and detailed design efforts for a one-person 'Mercury' Lightcraft, using computer-aided design and finite-element structural modeling techniques. In addition, they began construction of a 2.6 m-diameter, full-scale engineering prototype mockup. The mockup will be equipped with three robotic legs that 'kneel' for passenger entry and exit. More importantly, the articulated tripod gear is crucial for accurately pointing at, and tracking the laser relay mirrors, a maneuver that must be performed just prior to liftoff. Also accomplished were further design improvements on a 6-inch-diameter Lightcraft model (for testing in RPI's hypersonic tunnel), and new laser propulsion experiments. The resultant experimental data will be used to calibrate Computational Fluid Dynamic (CFD) codes and analytical laser propulsion models that can simulate vehicle/engine flight conditions along a transatmospheric boost trajectory. These efforts will enable the prediction of distributed aerodynamic and thruster loads over the entire full-scale spacecraft

Beta Risk and Regime Shift in Market Volatility

In this paper, we relate security returns in the thirty securities in the Dow Jones index to regime shifts in the market portfolio (S&P500) volatility. We model market volatility as a multiple-state Markov switching process of order one and estimate non-diversifiable security risk (beta) in the different market volatility regimes. We test the significance of the premium of the beta risk associated with the different market regimes and find evidence of a relationship between security return and beta risk when conditional on the up and down market movement.Markov regime-switching, Market volatility, Beta risk.