Abstract: According to one embodiment two-core optical fiber is provided for use in Brillouin distributed fiber sensor applications and systems. The two-core fiber includes a first and second core. Each core is configured to exhibit a Brillouin frequency shift greater than 30 Mhz relative to the other core. Further, each core possesses temperature and strain coefficients that differ from the other core. The cores can be configured to produce Brillouin frequency shift levels of at least 30 Mhz relative to one another. These differences in shift levels may be affected by adjustment of the material compositions, doping concentrations and/or refractive index profiles of each of the cores. These optical fibers may also be used in BOTDR- and BOTDA-based sensor systems and arrangements.

Abstract: Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon includes at least two core members formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ?15 microns and a cross-talk between adjacent core members is ??25 dB. In this embodiment each core member is single-moded with an index of refraction nc, and a core diameter dc. In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ?25 microns. A single cladding layer is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ?400 microns and an index of refraction ncl<nc.

Abstract: According to one embodiment two-core optical fiber is provided for use in Brillouin distributed fiber sensor applications and systems. The two-core fiber includes a first and second core. Each core is configured to exhibit a Brillouin frequency shift greater than 30 Mhz relative to the other core. Further, each core possesses temperature and strain coefficients that differ from the other core. The cores can be configured to produce Brillouin frequency shift levels of at least 30 Mhz relative to one another. These differences in shift levels may be affected by adjustment of the material compositions, doping concentrations and/or refractive index profiles of each of the cores. These optical fibers may also be used in BOTDR- and BOTDA-based sensor systems and arrangements.

Abstract: A two-core optical fiber is provided for use in Brillouin distributed fiber sensor applications and systems. The two-core fiber includes a first and second core. Each core is configured to exhibit a Brillouin frequency shift greater than 30 Mhz relative to the other core. Further, each core possesses temperature and strain coefficients that differ from the other core. The cores can be configured to produce Brillouin frequency shift levels of at least 30 Mhz relative to one another. These differences in shift levels may be effected by adjustment of the material compositions, doping concentrations and/or refractive index profiles of each of the cores. These optical fibers may also be used in BOTDR- and BOTDA-based sensor systems and arrangements.

Abstract: Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon includes at least two core members formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ?15 microns and a cross-talk between adjacent core members is ??25 dB. In this embodiment each core member is single-moded with an index of refraction nc, and a core diameter dc. In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ?25 microns. A single cladding layer is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ?400 microns and an index of refraction ncl<nc.

Abstract: Multi-core optical fibers are disclosed herein. According to one embodiment, a multi-core optical fiber includes a common outer cladding formed from silica-based glass and having a cladding index of refraction ncl. At least one single mode core element may be disposed in the common outer cladding. The at least one single mode core element may have a maximum index of refraction n1 sm. In addition, at least one multimode core element may be disposed in the common outer cladding, the at least one multimode core element having a maximum index of refraction n1 mm. The maximum refractive index n1 sm of the at least one single mode core element may be greater than the cladding index of refraction ncl, the maximum refractive index n1 mm of the at least one multi-mode core element may be greater than ncl, and a center-to-center spacing between adjacent core elements is greater than or equal to 25 ?m.

Abstract: Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon includes at least two core members formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ?15 microns and a cross-talk between adjacent core members is ??25 dB. In this embodiment each core member is single-moded with an index of refraction nc, and a core diameter dc. In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ?25 microns. A single cladding layer is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ?400 microns and an index of refraction nc1?nc.

Abstract: Polarization maintaining optical fibers and methods for making the same are disclosed herein. According to one embodiment, a polarization maintaining optical fiber includes a cladding portion and a core portion disposed in the cladding portion. The core portion includes a first core region having a first coefficient of thermal expansion CTE1 and a second core region having a second coefficient of thermal expansion CTE2. The first coefficient of thermal expansion CTE1 is not equal to the second coefficient of thermal expansion CTE2. At least one of the first core region and the second core region is non-circular symmetric with respect to a centerline of the polarization maintaining optical fiber.

Abstract: Polarization maintaining optical fibers and methods for making the same are disclosed herein. According to one embodiment, a polarization maintaining optical fiber includes a cladding portion and a core portion disposed in the cladding portion. The core portion includes a first core region having a first coefficient of thermal expansion CTE1 and a second core region having a second coefficient of thermal expansion CTE2. The first coefficient of thermal expansion CTE1 is not equal to the second coefficient of thermal expansion CTE2. At least one of the first core region and the second core region is non-circular symmetric with respect to a centerline of the polarization maintaining optical fiber.

Abstract: Multi-core optical fibers are disclosed herein. According to one embodiment, a multi-core optical fiber includes a common outer cladding formed from silica-based glass and having a cladding index of refraction ncl. At least one single mode core element may be disposed in the common outer cladding. The at least one single mode core element may have a maximum index of refraction n1 sm. In addition, at least one multimode core element may be disposed in the common outer cladding, the at least one multimode core element having a maximum index of refraction n1 mm. The maximum refractive index n1 sm of the at least one single mode core element may be greater than the cladding index of refraction ncl, the maximum refractive index n1 mm of the at least one multi-mode core element may be greater than ncl, and a center-to-center spacing between adjacent core elements is greater than or equal to 25 ?m.

Abstract: A two-core optical fiber is provided for use in Brillouin distributed fiber sensor applications and systems. The two-core fiber includes a first and second core. Each core is configured to exhibit a Brillouin frequency shift greater than 30 Mhz relative to the other core. Further, each core possesses temperature and strain coefficients that differ from the other core. The cores can be configured to produce Brillouin frequency shift levels of at least 30 Mhz relative to one another. These differences in shift levels may be effected by adjustment of the material compositions, doping concentrations and/or refractive index profiles of each of the cores. These optical fibers may also be used in BOTDR- and BOTDA-based sensor systems and arrangements.

Abstract: Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon includes at least two core members formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ?15 microns and a cross-talk between adjacent core members is ??25 dB. In this embodiment each core member is single-moded with an index of refraction nc, and a core diameter dc. In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ?25 microns. A single cladding layer is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ?400 microns and an index of refraction nc1?nc.

Abstract: A preform for forming a hollow-core, slotted photonic band-gap (PBG) optical fiber for use in an environmental sensor, and methods of forming such a fiber using the preform are disclosed. The preform comprises a slotted cladding tube that surrounds a slotted, hollow-core PBG cane. The slots in the cladding tube and PBG cane are longitudinally formed and substantially aligned with each other. When the preform is drawn, the slots merge to form an elongated side opening or slot in the resulting hollow-core PBG fiber.

Abstract: A method for determining a rotational characteristic of an optical fiber is disclosed. The method includes forming an orientation registration feature in an optical fiber preform and drawing an optical fiber from the preform such that the orientation registration feature formed in the optical fiber preform is imparted to the optical fiber. The optical fiber is then rotated about a longitudinal axis and the direction of rotation is periodically reversed. An orientation signal of the optical fiber is determined based on a position of the orientation registration feature as the optical fiber is rotated. A rotational characteristic of the optical fiber is then determined based on the orientation signal.

Abstract: A preform for forming a hollow-core, slotted photonic band-gap (PBG) optical fiber for use in an environmental sensor, and methods of forming such a fiber using the preform are disclosed. The preform comprises a slotted cladding tube that surrounds a slotted, hollow-core PBG cane. The slots in the cladding tube and PBG cane are longitudinally formed and substantially aligned with each other. When the preform is drawn, the slots merge to form an elongated side opening or slot in the resulting hollow-core PBG fiber. In one case, the slot reaches the hollow core upon drawing, while in another case a second step is used to extend the slot to connect to the hollow core. The fiber is used to form an environmental sensor for sensing the presence of a target substance in an environment. The slot formed in the PBG region of the fiber forms a ridge waveguide wherein a portion of the light that otherwise is confined to the hollow core as a bound mode travels in the slot.

Abstract: A method of fabricating a microstructure for an optical waveguide such as a photonic bandgap fiber is provided. The method includes the steps of assembling a stack of capillary tubes having substantially identical dimensions, fusing and redrawing the stack into a preform having a plurality of parallel holes of equal diameter, selecting a pattern of the holes for etching in order to increase their diameter, and plugging the unselected holes at one end of the preform against the flow of a pressurized etching fluid. Such plugging of the unselected holes is accomplished applying a layer of a gel-like sealant over the end of the preform, and then pushing the sealant into the holes to form sealant plugs in all of the holes. The sealant plugs are then removed from the selected holes by punching the sealant plugs out of the selected holes.