Special photonic crystal fibers
Large-mode-area (LMA) all-silica photonic crystal fibers (PCFs), which are specially designed with a limited number of air channels in cladding, are presented. An optimal value of relative channel diameter in the cladding of these fibers has been found (both theoretically and experimentally) that provides a single-mode regime of light propagation (at wavelength 633, 1330 and 1550 nm), low transmission and macrobending losses. Fabrication and theoretical modeling of special miniature LMA PCF tapers with selective transmission manufactured on a base of developed LMA PCFs were described. Application of these tapers for sensing with a high resolution of liquids refractive index, for sensing of high temperature in the 200-1000°C range, for temperature-insensitive measuring (in the 0-180°C range) of microstrain, for fast detection of hydrogen concentrations between 0-5.6 volume %, and for detection of organic vapors was presented.