Ofs Fitel, LLC

Fitel USA Corporation

Boston University

Ofs Fltel, LLC

University of Aarhus

Ofs Fitel Llc, a Delaware Limited Liability Company

Poul Kristensen

John Michael Fini

Lars Gruner-Nielsen

David John DiGiovanni

Tommy Geisler

Peter Ingo Borel

Siddharth Ramachandran

Jeffrey W Nicholson

Philip G Westergaard

Quang Nghi Trong Le

Marie Wandel

Andrew Douglas Yablon

Robert M Atkins

Alice Weimin Liu

Stig Nissen Knudsen

Kai H Chang

Jake Bromage

Jan Levin Nielsen

Morten Østergaard Pedersen

Lu Yan

Peter Balling

Juha-Matti Savolainen

A vortex optical fiber for use in an illumination subsystem of an optical imaging system (e.g., a stimulated emission depletion (STED) microscopy system) includes an elongated optically transmissive medium having a set of regions including a core region, a trench region surrounding the core region, a ring region surrounding the trench region, and a cladding region, the set of regions having a doping profile providing a &#x394;nfor vector modes in an LPmode group of greater than 1&#xd7;10in the visible spectral range so as to simultaneously guide stable Gaussian and orbital angular momentum (OAM) carrying modes at corresponding visible wavelengths.

Optical imaging system employing vortex fiber for multiple-mode illumination

A specialized, dispersion-controlled fiber is particularly configured to exhibit a relatively uniform dispersion (D) over a broad spectral range (for example, 1000 nm to 2000 nm). The specialized fiber exhibits an essentially constant attenuation (&#x3b1;) over this same spectral range so that the fiber is defined as having a high 'figure of merit' (FoM) where FoM is defined as |D|/&#x3b1;. The specialized fiber is well-suited for use as a pulse stretcher, providing the ability to separate out wavelength constituents of an extremely short (fs, ps) broadband pulse into the ns range, for example.

Optical fiber with specialized figure-of-merit and applications therefor

A distributed Brillouin sensor system comprising a pump laser, and a combined fiber assembly including at least a first optical fiber section and a second optical fiber section is described. The pump laser is arranged so as to send a pump signal into a first end of combined fiber assembly, and the detector system is arranged to detect Brillouin backscattering from the combined fiber assembly. The combined fiber assembly is characterized by the first section having a low Brillouin gain, and the second fiber section having a high Brillouin gain.

Distributed brillouin sensor

A distributed Brillouin sensor system comprising a pump laser, a Brillouin sensor fiber, and a detector system is described. The pump laser is arranged so as to send a pump signal into a first end of the Brillouin sensor fiber, and the detector system is arranged to detect Brillouin backscattering from the Brillouin sensor fiber. The Brillouin sensor fiber is characterized by having a negative dispersion, and further by an effective area of the sensor fiber being less than or equal to 50 &#x3bc;m.

Distributed Brillouin sensor

A few-moded fiber is doped such that spatial modes of a signal exhibit different magnetic-field-dependent effects. Based on these magnetic-field-dependent effects, one can determine the electric current that induced a magnetic field that caused these effects.

Few-moded fiber for sensing current

Techniques for analyzing output modal content of optical fibers that support more than one spatial mode are disclosed. These techniques are based on spatially resolving interference between co-propagating modes and constructing a spatial beat pattern between the co-propagating modes. By doing so, these techniques provide information about the modes that propagate along the optical fiber.

Measuring modal content of multi-moded fibers

Described is a method of fabricating an optical fiber preform that includes a deep index trench comprising a shallower outer trench portion formed on a substrate tube and a deeper inner trench portion formed on the shallower outer trench portion. Each of the shallower outer trench and deeper inner trench portions comprises multiple silica layers. The method comprises the steps of: (1) forming each layer of the shallower outer trench portion in a single-pass deposition of a F-containing silica layer; and (2) forming each layer of the deeper inner portion in a double-pass deposition in which, in a first pass, a layer of silica soot is deposited and then, in a second pass, the soot is sintered in the presence of SiF.

Method of making an optical fiber with trench region in its index profile

An optical fiber that is relatively insensitive to bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode, the cladding region including (i) an outer cladding region having a refractive index less than that of the core region, (ii) an annular cladding pedestal region having a refractive index higher than that of the outer cladding region and comparable to that of the core region, and (iii) an annular cladding inner trench region disposed between the core region and the pedestal region, the inner trench region having a refractive index less than that of the outer cladding region. In one embodiment, the fiber also includes a (iv) an annular cladding outer trench region disposed between the pedestal region and the outer cladding region, the outer trench region having a refractive index less than that of the outer cladding region. In addition, to suppress HOMs the pedestal region is configured to resonantly couple at least one other transverse mode of the core region to at least one transverse mode of the pedestal region. Such fiber is advantageously used as access fiber, but may have other applications, such as sensor fiber.

Bend insensitivity in single mode optical fibers

Described are multi-tube fabrication techniques for making an optical fiber that is relatively insensitive to bend loss and alleviates the problem of catastrophic bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode. The cladding region includes (i) an outer cladding region, (ii) an annular pedestal (or ring) region, (iii) an annular inner trench region, and (iv) an annular outer trench region. The pedestal region and the outer cladding region each have a refractive index relatively close to that of the outer cladding region. In order to suppress HOMs the pedestal region is configured to resonantly couple at least one (unwanted) transverse mode of the core region (other than the fundamental mode) to at least one transverse mode of the pedestal region.

Methods of making single mode optical fibers with reduced bend sensitivity and catastrophic bend loss

An optical fiber that is relatively insensitive to bend loss and alleviates the problem of catastrophic bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode. The cladding region includes (i) an outer cladding region, (ii) an annular pedestal (or ring) region, (iii) an annular inner trench region, and (iv) an annular outer trench region. The pedestal region and the outer cladding region each have a refractive index relatively close to that of the outer cladding region. In order to suppress HOMs the pedestal region is configured to resonantly couple at least one (unwanted) transverse mode of the core region (other than the fundamental mode) to at least one transverse mode of the pedestal region. In a preferred embodiment, the fiber is configured so that, at a signal wavelength of approximately 1550 nm, its bend loss is no more than about 0.1 dB/turn at bend radius of 5 mm and is no more than about 0.02 dB/turn at a bend radius of 10 mm. In addition, in one embodiment, the core region also includes an inner core region and an annular outer core (or shelf) region surrounding the inner core region. The outer core region extends radially a distance of less than 9 &#x3bc;m from the fiber axis. In another embodiment, the inner trench region includes an annular inner portion and an annular outer (or step) portion surrounding said inner portion. The refractive index of the step portion is greater than that of the inner portion. In a preferred embodiment, both of the foregoing features of the core region and the inner trench region are incorporated in the fiber. Also described are multi-tube fabrication techniques for making such fibers.

Reduced bend sensitivity and catastrophic bend loss in single mode optical fibers and method of making same

The output modal content of optical fibers that contain more than one spatial mode may be analyzed and quantified by measuring interference between co-propagating modes in the optical fiber. By spatially resolving the interference, an image of the spatial beat pattern between two modes may be constructed, thereby providing information about the modes supported by the optical fiber.

Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.

Growing community of inventors

Valby, Denmark

Poul Kristensen