We demonstrate a highly manufacturable, low-cost, compatible Single-Polarization Fiber (PZF), which offers
the widest polarization bandwidth ever reported in commercial fibers, combined with superior polarization
extinction ratio and performance consistency. The principle of the design is discussed in this paper and the full
spectral attenuation results shown. We demonstrate the exceptional performance of the fiber for different fiber
lengths and layouts. Experimental results show that the Single-Polarization fiber of this study exhibits a
Polarization Extinction Ratio (PER) greater than 40dB, and a polarizing bandwidth wider than 200nm,
measured on fiber lengths as short as four meters. In addition, PZF is designed with a circular mode field, which
makes it low-loss and highly compatible with standard single mode fiber systems and devices.
We report on a new class of novel optical fiber structures, designed for use in harsh environments typical of Oil and Gas Applications. Specifically, we focus on fiber designs that alleviate the effects of hydrogen ingression and its associated darkening of optical fibers in harsh environments. We demonstrate theoretically, how a carbon coated optical fiber structure consisting of an array of randomly or systematically placed voids running along the length of the fiber, can lead to significantly reduced hydrogen ingression effects. The array of voids can be of arbitrarily varying shapes and sizes, along the length of the fiber. We derive an equation describing the increase in the fiber lifetime as a function of the average cross-sectional fraction of voids in the fiber. Fiber darkening effects are predicted to decrease by factors of as much as x10, for moderately low fraction of voids in the fiber cross-section. Theoretical predictions are confirmed experimentally by performing ingression tests in a hydrogen test chamber with on-line monitoring capability, simulating down-hole temperatures and pressures. Additional geometric factors, such as fiber diameter, that may also be optimized to further improve the hydrogen ingression resistance of fibers are discussed; in this vein a new larger form-factor fiber, different from the standard 125um fiber is proposed. Finally, the lifetime predictions greater than 5-10 years obtained for such void-filled optical fibers in typical down-hole conditions make them extremely attractive candidates for use in Oil and Gas applications such as well monitoring and logging.
Optical fibers with improved hermeticity, strength and chemical resistance are presented. Specifically, we provide data demonstrating the resistance of carbon coated optical fibers to hydrogen (high partial pressures and temperatures) and acidic environments. As well we provide data and analysis indicating that carbon coated fibers with increased n-values provide long lifetimes under stressed conditions.
Nd:YAG laser systems, coupled to silica fibers, have shown great benefits as surgical tools. Using the laser system with a bare silica fiber, laser surgeons can photocoagulate tissue to depths of 4 to 5 mm in a non-contact mode. In a contact mode, incision and cauterization of the nearby tissue can be achieved. Although these two capabilities provide powerful tools for hemostatic procedures, research performed at Iowa State University has shown that the silica fiber tips undergo extensive damage when in contact with tissue. Chemical and thermal degradation of the silica glass surface plays a key role. Damaged fibers do not transmit a significant fraction of the laser light launched down them. Instead, essentially all of the laser energy is converted to heat at the contact point. The tip can then be used only to incise tissue. We report here on the development and characterization of a new optical fiber that offers improved chemical resistance and also high temperature resistance. The new fibers were pulled from glass rods with a composition of 92.5 wt.% SiO2 and 7.5 wt.% TiO2 and then cladded with a fluorinated hard polymer. The new fibers effectively deliver energy even after the fiber comes into contact with tissue while the silica fiber tips undergo catastrophic damage. Also, preliminary clinical testing of the new fibers has demonstrated the stability of the fibers in contact with tissue during gynecological surgical procedures.