A technical meeting also took place at the end of June between members of the `Ohana committee and fiber manufacturers and users. One of the very fundamental questions, albeit one that does not need an immediate or an unequivocal decision, is what fibers to use. On the one hand, silicate fibers are commonly available and especially polarization maintaining components with low transmission loss exist. These fibers transmit J and H bands (1,2 and 1.6 microns). However, those are the wavelengths where adaptive optics does not provide the best correction and coupling efficiency will be lower. Also, the fibers are sensitive to temperature and need to be actively controlled (the birefringence dispersion needs to be equal in both arms of the interferometer to maximize fringe contrast, and it depends on temperature, but also the fiber bending and twisting status; the use of polarization maintaining fibers helps to overcome this effect). On the other hand are fluoride glass fibers that transmit the K band (2.2 microns) and are fairly insensitive to temperature. Yet, polarization maintaining components are not as advanced yet as for silica fibers.
Independantly of the different technical challenges linked with each type of fiber, there is a scientific motivation to actually use both types, namely access to the J, H and K bands. Whatever the case may, the concerned parties (Gwenael Maze from "Le Verre Fluoré" and Francois Reynaud, from IRCOM in Limoges) were very enthusiastic, and we hope to be able to further these collaborations in the future.