Low loss coatings for the VIRGO large mirrors

présentée par L. PinardThe goal of the VIRGO program is to build a giant Michelson type interferometer (3 kilometer long arms) to detect gravitational waves. Large optical components (350 mm in diameter), having extremely low loss at 1064 nm, are needed. Today, the Ion beam Sputtering is the only deposition technique able to produce optical components with such performances. Consequently, a large ion beam sputtering deposition system was built to coat large optics up to 700 mm in diameter. The performances of this coater are described in term of layer uniformity on large scale and optical losses (absorption and scattering characterization). The VIRGO interferometer needs six main mirrors. The first set was ready in June 2002 and its installation is in progress on the VIRGO site (Italy). The optical performances of this first set are discussed. The requirements at 1064 nm are all satisfied. Indeed, the absorption level is close to 1 ppm (part per million), the scattering is lower than 5 ppm and the R.M.S. wavefront of these optics is lower than 8 nm on 150 mm in diameter. Finally, some solutions are proposed to further improve these performances, especially the absorption level (lower than 0.1 ppm) and the mechanical quality factor Q of the mirrors (thermal noise reduction)

Design and fabrication of an all fiber-optical add/drop element based on a taper-resonator-taper structure

In this letter, we designed and fabricated an all fiber-optic Add/Drop element based on Taper-Resonator-Taper (TRT) structure, assembling it with V-shaped grooves. We proposed a novel configuration composed of two microspheres and three taper fibers. We can cascade this kind of TRT structure, it will be potentially used as multi-wavelengths Optical Add/Drop Multiplexer and Wavelength Division Multiplexer/Demultiplexer

A novel cladding-mode coupler formed by long period fiber gratings and microsphere resonator

There are numerous methods for evanescently coupling energy into the modes of a sphere. In this paper, we provided a new methods, used long period fiber gratings (LPFG) coupling evanescent wave into microsphere resonator. We have illustrated this coupling mechanism in theoretical. As an potentially application, we describe a four-port passive Add/Drop device based on the microsphere-LPFG coupling mechanism

An innovative integral field unit upgrade with 3D-printed micro-lenses for the RHEA at Subaru

In the new era of Extremely Large Telescopes (ELTs) currently under construction, challenging requirements drive spectrograph designs towards techniques that efficiently use a facility's light collection power. Operating in the single-mode (SM) regime, close to the diffraction limit, reduces the footprint of the instrument compared to a conventional high-resolving power spectrograph. The custom built injection fiber system with 3D-printed micro-lenses on top of it for the replicable high-resolution exoplanet and asteroseismology spectrograph at Subaru in combination with extreme adaptive optics of SCExAO, proved its high efficiency in a lab environment, manifesting up to ~77% of the theoretical predicted performance