Abstract: The invention is a hollow fiber with, over the full length of the fiber and between each fiber channel (3, 4) and the core, at least one stress zone (5, 6) to create an anisotropic stress distribution which subjects the fiber core to a tensile stress. The cable design is advantageous in that it is possible to control the sign of the fiber intrinsic birefringence. The cable is thus advantageous for use as a pressure sensor or pressure transducer.

Abstract: The present invention concerns a transistor of semiconductor materials of the 3-5 group on silicon of the type comprising a silicon substrate, at least one layer of semi-insulating 3-5 material and several doped layers of 3-5 group semiconductor material in which is defined at least one conducting channel equipped with a gate metallization, each channel being situated between two access regions alternately known as source and drain, each source and drain regions with a metallization, one of the two access regions to a channel being electrically and thermally connected to the silicon substrate. In accordance with the invention, the transistor comprises between the silicon substrate and the semi-insulating layer of 3-5 group semiconductor material, at least one buffer layer of intrinsic silicon.