Abstract: The invention relates to optical fiber communications. A multicore optical fiber comprises at least two light-guiding cores made of doped fused silica with refractive indices nc1, nc2, nck, each light-guiding core of the at least two light-guiding cores being surrounded by a respective arbitrarily shaped inner reflecting cladding made of fused silica or doped fused silica with refractive indices nc11, nc12, nclk, which are less than the refractive indices nc1, nc2, nck of respective light-guiding cores; a continuous or intermittent barrier region made of fused silica and having an arbitrary cross-sectional shape, the barrier region being formed in the space between the inner reflecting claddings and an outer cladding of fused silica with refractive index n0, the barrier region having refractive index nb, which is less than the refractive index of each of the inner reflecting claddings; and an external protective coating.

Abstract: The invention relates to optical fiber communications. A multicore optical fiber comprises at least two light-guiding cores made of doped fused silica with refractive indices nc1, nc2, nck, each light-guiding core of the at least two light-guiding cores being surrounded by a respective arbitrarily shaped inner reflecting cladding made of fused silica or doped fused silica with refractive indices nc11, nc12, nclk, which are less than the refractive indices nc1, nc2, nck of respective light-guiding cores; a continuous or intermittent barrier region made of fused silica and having an arbitrary cross-sectional shape, the barrier region being formed in the space between the inner reflecting claddings and an outer cladding of fused silica with refractive index n0, the barrier region having refractive index nb, which is less than the refractive index of each of the inner reflecting claddings; and an external protective coating.

Abstract: The inventions relate to measurements of a hydrostatic and/or fast-changing pressure by optical means, and are suitable for aerodynamic investigations of aircraft and small spacecraft, in robotics, including small force micro-clamps, in remote pressure monitoring (in wells, vessels, cylinders), in medicine and medical and biological investigations, hydroacoustics, security systems. The object is to improve the sensitivity and enhance the temperature and vibration stability of a pressure sensor. The pressure sensor is a low Q-factor Fabry-Perot cavity/interferometer 6 at the end of a single-mode optical fiber 1 with the 4% Fresnel reflection from the silica glass/air interface. Another movable mirror of the cavity is formed by an end face 10 of a short (1-3 mm) optical fiber length 9 having a small inertial mass and inserted into the center of a flexible membrane 9 of 500-700 &mgr;m in diameter, tightly sealing a small air volume of about 1-3 mm3 inside a second capillary 3 with the external diameter of 0.

Abstract: The inventions relate to measurements of a hydrostatic and/or fast-changing pressure by optical means, and are suitable for aerodynamic investigations of aircraft and small spacecraft, in robotics, including small force micro-clamps, in remote pressure monitoring (in wells, vessels, cylinders), in medicine and medical and biological investigations, hydroacoustics, security systems. The object is to improve the sensitivity and enhance the temperature and vibration stability of a pressure sensor. The pressure sensor is a low Q-factor Fabry-Perot cavity/interferometer 6 at the end of a single-mode optical fiber 1 with the 4% Fresnel reflection from the silica glass/air interface. Another movable mirror of the cavity is formed by an end face 10 of a short (1-3 mm) optical fiber length 9 having a small inertial mass and inserted into the center of a flexible membrane 9 of 500-700 &mgr;m in diameter, tightly sealing a small air volume of about 1-3 mm3 inside a second capillary 3 with the external diameter of 0.