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In this paper, we study several designs for interferometric gravitational wave detectors, and the potential for enhancing their performance with a fast-light medium. First, we explore the effect of such a medium on designs similar to those already planned for Advanced LIGO. Then we review the zero-area Sagnac interferometer for GW detection, comparing its properties against the more conventional GW detector based on a Michelson interferometer. We next describe a modified version of such a detector where the Sagnac interferometer is replaced by a zero-area Sagnac ring resonator fed by an external laser. We then consider a GW detector based on an active, zero-area Sagnac ring resonator, where a gain medium is present inside the cavity. Finally, we show that if a medium with negative dispersion, which yields the fast-light effect, is also present inside this detector, then its sensitivity to GW strain is enhanced by the inverse of the group index of the dispersive medium. We describe conditions under which this enhancement factor could be as large as 105. [ABSTRACT FROM AUTHOR]

This paper describes an optical configuration for generating dual-focus from a single laser incident beam. The generated two foci have nearly equivalent spot size and both fall on the optical axis of the focusing optics, but at different focal lengths. The dual-focus optics allows for variations of the laser power of each focal point and the distance between the two focal points. The advantages of dual-focus ablation were demonstrated with a nanosecond UV laser dicing silicon substrates. The experimental results show that, compared to conventional single focus, dual-focus improves ablation rate by a factor of 2–4. [ABSTRACT FROM AUTHOR]

Broadband amplified spontaneous emission (ASK) at a peak wavelength of 1.85 μm from Tm:Ho-doped silica fibre sources is reported, using in-band pumping from a Yb:Er co-doped fibre laser operating at 1.61 μm. A maximum total output power from both ends of greater than 80mW with slope efficiency >14% has been achieved. An ASF. bandwidth at FWHM of near 70 nm was measured from the forward signal for the output power from 2–40 mW. The total fluorescence spectral width is >200 nm. This broadband ASE source has potential applications in optical metrology, fibre sensors, loss and dispersion tests on optical fibres, spectroscopy and medical imaging. including optical coherence tomography. A review of different pumping schemes in generating ASE around 1.9 μm in the Tm-doped fibre is given. Also the nature of three-level ASE and in-band pumping of Tm:Ho-doped silica fibre are also discussed. The results in this paper confirm that in-band pumped Tm-silica fibre is a route to achieve high power broadband output around 1.8 mu;m. [ABSTRACT FROM AUTHOR]