Transient gas-induced differential refractive index effects in as-drawn hollow core optical fibers.

When a hollow core fiber is drawn, the core and cladding holes within the internal cane geometry are pressurized with an inert gas to enable precise control over the internal microstructure of the fiber and counteract surface tension forces. Primarily by considering the temperature drop as the fiber passes through the furnace and the geometrical transformation of the internal microstructure from preform-to-fiber, we recently established that the gas pressure within the final 'as-drawn' fiber is substantially below atmospheric pressure. We have also established that slight changes in the gas refractive index within the core and surrounding cladding holes induced by changes in gas pressure are sufficient to significantly affect both the modality and loss of the fiber.

Optical time domain backscattering of antiresonant hollow core fibers.

Today's lowest-loss hollow core fibers are based on antiresonance guidance. They have been shown both theoretically and experimentally to have very low levels of backscattering arising from the fiber structure - 45 dB below that of traditional optical fibers with a solid silica glass core. This makes their longitudinal characterization using conventional reflectometric techniques very challenging.

Hollow-core resonator fiber optic gyroscope using nodeless anti-resonant fiber.

Resonator fiber optic gyroscope (RFOG) performance has hitherto been limited by nonlinearity, modal impurity, and backscattering in the sensing fibers. The use of hollow-core fiber (HCF) effectively reduces nonlinearity, but the complex interplay among glass and air-guided modes in conventional HCF technologies can severely exacerbate RFOG instability. By employing high-performance nested anti-resonant nodeless fiber, we demonstrate long-term stability in a hollow-fiber RFOG of 0.