Brownian Thermal Noise in Multilayer Coated Mirrors

We analyze the Brownian thermal noise of a multi-layer dielectric coating, used in high-precision optical measurements including interferometric gravitational-wave detectors. We assume the coating material to be isotropic, and therefore study thermal noises arising from shear and bulk losses of the coating materials. We show that coating noise arises not only from layer thickness fluctuations, but also from fluctuations of the interface between the coating and substrate, driven by internal fluctuating stresses of the coating. In addition, the non-zero photoeleastic coefficients of the thin films modifies the influence of the thermal noise on the laser field. The thickness fluctuations of different layers are statistically independent, however, there exists a finite coherence between layers and the substrate-coating interface. Taking into account uncertainties in material parameters, we show that significant uncertainties still exist in estimating coating Brownian noise.Comment: 26 pages, 18 figure

Thermoelastic dissipation in inhomogeneous media: loss measurements and displacement noise in coated test masses for interferometric gravitational wave detectors

The displacement noise in the test mass mirrors of interferometric gravitational wave detectors is proportional to their elastic dissipation at the observation frequencies. In this paper, we analyze one fundamental source of dissipation in thin coatings, thermoelastic damping associated with the dissimilar thermal and elastic properties of the film and the substrate. We obtain expressions for the thermoelastic dissipation factor necessary to interpret resonant loss measurements, and for the spectral density of displacement noise imposed on a Gaussian beam reflected from the face of a coated mass. The predicted size of these effects is large enough to affect the interpretation of loss measurements, and to influence design choices in advanced gravitational wave detectors.Comment: 42 pages, 7 figures, uses REVTeX

Excess Mechanical Loss Associated with Dielectric Mirror Coatings on Test Masses in Interferometric Gravitational Wave Detectors

Interferometric gravitational wave detectors use mirrors whose substrates are formed from materials of low intrinsic mechanical dissipation. The two most likely choices for the test masses in future advanced detectors are fused silica or sapphire. These test masses must be coated to form mirrors, highly reflecting at 1064nm. We have measured the excess mechanical losses associated with adding dielectric coatings to substrates of fused silica and calculate the effect of the excess loss on the thermal noise in an advanced interferometer.Comment: Submitted to LSC (internal) review Sept. 20, 2001. To be submitted to Phys. Lett.

Total Synthesis and Derivation of Humulones and Lupulones as Possible Biologically Active Agents

Humulones and lupulones have affirmed themselves as key ingredients in the multi-billion dollar brewing industry. Originally exploited for their bacteriostatic properties, these compounds also exhibit high levels of biological activity against a variety of diseases. Although quantifiable, the isolation and separation of specific humulones and lupulones has proven difficult, thus establishing efficient synthetic routes will be of value to those desiring exact bittering qualities and to the pharmaceutical community. Our investigations are towards developing a synthetic route to a library of humulones, lupulones, and their derivatives as possible biologically active agents against myriad diseases. The key step in our efficient syntheses of individual humulones is a copper mediated asymmetric oxidative dearomatization involving a chiral ligand. New compounds will be biologically tested through our collaborations. Active agents may lead to a transformation in hops as sources to the next generation of medicines