Ofs Fitel, LLC

Lucent Technologies Inc.

At+t Corp.

At&t Bell Laboratories

Fitel USA Corporation

Patrick William Wisk

Man Fei Yan

David W Peckham

Dennis J Trevor

Peter Ingo Borel

Jorgen Ostgaard Olsen

Ole A Levring

Benyuan Zhu

Rasmus V S Jensen

John Burnette MacChesney

Fan Ren

Thomas Edward Stockert

Tommy Geisler

Stephen J Pearton

Cammy R Abernathy

Jeffrey W Nicholson

James Dennis Wynn

Rasmus V Jensen

An optical preform manufacturing process is disclosed in which an alkali dopant is deposited between an optical fiber core rod and an optical fiber cladding jacket. Depositing the alkali dopant between the core rod and the cladding jacket permits diffusion of the alkali dopants into the core during fiber draw when the core and the cladding are at their respective transition (or vitrification) temperatures. Introduction of the alkali dopants between the core rod and the cladding jacket also permits decoupling of the alkali doping process from one or more of other optical preform manufacturing processes. The optical preform manufacturing process can also include placing alkali dopants between an optical fiber inner cladding jacket and an optical fiber outer cladding jacket to reduce the glass viscosity during fiber draw.

Viscocity-reducing dopants in optical fibers

An optical fiber has a core region that is doped with one or more viscosity-reducing dopants in respective amounts that are configured, such that, in a Raman spectrum with a frequency shift of approximately 600 cm, the fiber has a nanoscale structure having an integrated D2 line defect intensity of less than 0.025. Alternatively, the core region is doped with one or more viscosity-reducing dopants in respective amounts that are configured such that the fiber has a residual axial compressive stress with a stress magnitude of more than 20 MPa and a stress radial extent between 2 and 7 times the core radius. According to another aspect of the invention a majority of the optical propagation through the fiber is supported by an identified group of fiber regions comprising the core region and one or more adjacent cladding regions. The fiber regions are doped with one or more viscosity-reducing dopants in respective amounts and radial positions that are configured to achieve viscosity matching among the fiber regions in the identified group.

Optical fiber with low loss and nanoscale structurally homogeneous core

The core region of an optical fiber is doped with chlorine in a concentration that allows for the viscosity of the core region to be lowered, approaching the viscosity of the surrounding cladding. An annular interface region is disposed between the core and cladding and contains a concentration of fluorine dopant sufficient to match the viscosity of the core. By including this annular stress accommodation region, the cladding layer can be formed to include the relatively high concentration of fluorine required to provide the desired degree of optical signal confinement (i.e., forming a 'low loss' optical fiber). The inclusion of the annular stress accommodation region allows for the formation of a large effective area optical fiber that exhibits low loss (i.e., &#x3c;0.19 dB/km) in both the C-band and L-band transmission ranges.

Low loss optical fiber and method of making the same

The core region of an optical fiber is doped with chlorine in a concentration that allows for the viscosity of the core region to be lowered, approaching the viscosity of the surrounding cladding. An annular interface region is disposed between the core and cladding and contains a concentration of fluorine dopant sufficient to match the viscosity of the core. By including this annular stress accommodation region, the cladding layer can be formed to include the relatively high concentration of fluorine required to provide the desired degree of optical signal confinement (i.e., forming a 'low loss' optical fiber).

A discrete Raman amplifier comprises a Raman gain fiber, an input port into the Raman gain fiber for receiving optical signals to be Raman amplified, and an output port out of the Raman gain fiber for emitting Raman-amplified optical signals. A pump light input provides pump light to the Raman gain fiber at a plurality of wavelengths so as to provide Raman amplification over the selected signal wavelength range. Within both the pump light wavelength range and the selected signal wavelength range, the Raman gain fiber has only positive chromatic dispersion, and the Raman gain fiber has a moderate effective area.

Discrete raman amplifier

An optical waveguide has a refractive index variation that is structured to provide the fiber, over a wavelength operating range, with an effective area supporting multiple Stokes shifts and with a negative dispersion value at a target wavelength within the wavelength operating range. The refractive index variation is further structured to provide the fiber with a finite LPcutoff at a wavelength longer than the target wavelength, whereby the LPcutoff wavelength provides a disparity, for a selected bending diameter, between macrobending losses at the target wavelength and macrobending losses at wavelengths longer than the target wavelength, whereby Raman scattering is frustrated at wavelengths longer than the target wavelength.

Filter fiber for use in Raman lasing applications and techniques for manufacturing same

The specification describes the production of optical fibers and optical fiber preforms using Chemical Powder Deposition (CPD). In this process a slurry of silica powders and dopant powders in a liquid carrier is prepared and the inside surface of a silica glass starter tube is coated with the slurry, then dried. The coating is then consolidated and the tube collapsed as in the conventional MCVD process. Multiple coatings, and coatings with varying compositions, can be used to produce any desired profile. In an alternative embodiment, doped silica glass of the desired final composition is prepared, and then pulverized to form the powder for the slurry. In both embodiments, the use of powders of known composition in the slurry allows direct control over the final glass composition, as compared with conventional processes in which the composition in the final glass is indirectly controlled by control of the thermodynamics of a vapor phase reaction.

Chemical powder deposition method for the manufacture of optical fiber preforms and optical fibers

Optical fiber design for secure tap proof transmission

The specification describes a process and apparatus for collapsing preform tubes in Modified Chemical Vapor Deposition processes. The problem of bubble formation during tube collapse was found to be attributable to excess dopant vapor pressure emitted from the hot zone during the final stage of tube collapse. This excess pressure is controlled by cooling the tube in advance of the torch, thereby decreasing the viscosity of the dopant vapor and increasing its transport rate. This is found to reduce internal tube pressure and eliminate bubble formation in the collapsed preform.

Optical fiber manufacture

In accordance with the invention, aluminum-containing layers are grown by molecular beam processes using as an arsenic precursor phenylarsine (PhAs). Because PhAs is more reactive than arsine and less reactive than arsenic, it decomposes selectively on III-V surfaces but not on mask materials. Thus in contrast to conventional processes, growth using PhAs permits selective growth on unmasked gallium arsenide surfaces but inhibits growth on typical mask materials such as silicon nitride.

Method for selectively growing aluminum-containing layers

In accordance with the invention, gallium-containing layers are grown by molecular beam processes using as an arsenic precursor a compound of the dialkylaminoarsenic family (DAAAs) such as tris-dimethylamino arsenic (DMAAs). In contrast to conventional arsenic sources, DAAAs act as carbon 'getters'. When DAAAs are used as an arsenic source, the DAAAs getter carbon impurities from the gallium source. Thus, for example, DAAAs can be used as an arsenic source in combination with TMG as a gallium source to selectively grow high purity or n-type layers of gallium arsenide at low temperatures below 600.degree. C. In addition DMAAs has been found to be an excellent cleaning agent for gallium arsenide materials.

Growing community of inventors

Green Brook, NJ, United States of America

Patrick William Wisk