This award supports research on improving optical coatings for next generation interferometric gravitational wave detection, Advanced LIGO and beyond. The peak sensitivity of Advanced LIGO is limited by thermal noise from the optical coatings applied to the Advanced LIGO test masses. In other words, the rate at which we can expect to detect gravitational wave events with Advanced LIGO goes up as coating thermal noise is reduced. Another significant noise source due to the optical coatings and affecting the rate of potential detections is thermo-optic noise from the optical coatings. In addition to the significant effect on Advanced LIGO, these noise sources place serious limits on the potential for future ground-based interferometric gravitational wave detectors. This award supports research to characterize and reduce the level of both thermal noise and thermo-optic noise from prototype coatings for Advanced LIGO and for potential future upgrades to Advanced LIGO. Other coating properties, such as optical scatter are also investigated when appropriate.
Embry-Riddle Aeronautical University is a technically oriented institution attracting a large number of undergraduate physics students interested in participating in faculty research. This award enables a number of those students, particularly in the space physics degree program, to engage in a very significant way with LIGO-related research. Several Embry-Riddle students involved in the P.I.'s research have gone on to participate in external LIGO-related internships such as the LIGO SURF program at Caltech and as undergraduate researchers at Glasgow University in Scotland. These experiences help to propel our students to fruitful carears in science and research.
The outcomes from this grant were: 1. An increased understanding of the material properties needed to make (multilayer dielectric) mirrors better for use in extremely sensitive measurements. The material properties required to make low-noise optical cavities were the ones we concentrated on. They were: resonant and non-resonant mechanical loss (friction) of the mirror coatings, the stiffness of the mirror coating, the thermal expansion coefficient of the mirror coatings, and the rate of change of the mirror coating material indices of refraction with temperature. 2. Nine undergraduates obtained extensive training and laboratory research experience. Numerous additional undegraduates "got their feet wet" by working on the grant for short periods. While it is sometimes considered the business of universities to train undergraduates for careers in research, NSF "Research at Undergraduate Institution" (RUI) grants like the one I am reporting on are a crucial element in enabling small, primarily undergraduate, universities to offer their students research experience. Without research experience, it is difficult for students to understand why they should choose a career in research over a better paid career in some other area. Of the nine students that worked extensively with me under the auspices of the grant 5 have chosen careers in research. That is more than double the rate of other physics students at our institution.
