FreshPatents.com Logo
stats FreshPatents Stats
 3  views for this patent on FreshPatents.com
2012: 1 views
2010: 2 views
Updated: January 23 2015
newTOP 200 Companies
filing patents this week



Advertise Here
Promote your product, service and ideas.

    Free Services  

  • MONITOR KEYWORDS
  • Enter keywords & we'll notify you when a new patent matches your request (weekly update).

  • ORGANIZER
  • Save & organize patents so you can view them later.

  • RSS rss
  • Create custom RSS feeds. Track keywords without receiving email.

  • ARCHIVE
  • View the last few months of your Keyword emails.

  • COMPANY DIRECTORY
  • Patents sorted by company.

Follow us on Twitter
twitter icon@FreshPatents

Browse patents:
Next →
← Previous

Bend resistant multimode optical fiber


Title: Bend resistant multimode optical fiber.
Abstract: Bend resistant multimode optical fibers are disclosed herein. Multimode optical fibers disclosed herein comprise a core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion comprising a depressed relative refractive index. ...


USPTO Applicaton #: #20100272406 - Class: $ApplicationNatlClass (USPTO) -
Inventors: Dana Craig Bookbinder, Ming-jun Li, Daniel Aloysius Nolan



view organizer monitor keywords


The Patent Description & Claims data below is from USPTO Patent Application 20100272406, Bend resistant multimode optical fiber.

CROSS-REFERENCE TO RELATED APPLICATIONS

- Top of Page


This application claims the benefit of, and priority to U.S. Provisional Patent Application No. 60/879,164 filed on Jan. 8, 2007, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

- Top of Page


1. Field of the Invention

The present invention relates generally to optical fibers, and more specifically to multimode optical fibers.

2. Technical Background

Corning Incorporated manufactures and sells InfiniCor® 62.5 μm optical fiber, which is multimode optical fiber having a core with a maximum relative refractive index of 2% and 62.5 μm core diameter, as well as InfiniCor® 50 μm optical fiber, which is multimode optical fiber having a core with a maximum relative refractive index of 1% and 50 μm core diameter.

SUMMARY

- Top of Page


OF THE INVENTION

Bend resistant multimode optical fibers are disclosed herein. Multimode optical fibers disclosed herein comprise a graded-index core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion, or “depressed cladding ring” or “ring”, comprising a depressed relative refractive index, relative to another portion of the cladding. Preferably, the refractive index profile of the core has a parabolic shape. The depressed-index annular portion comprises glass comprising a plurality of holes, or fluorine-doped glass, or fluorine-doped glass comprising a plurality of holes.

In some embodiments that comprise a cladding with holes, the holes can be non-periodically disposed in the depressed-index annular portion. By “non-periodically disposed” or “non-periodic distribution”, we mean that when one takes a cross section (such as a cross section perpendicular to the longitudinal axis) of the optical fiber, the non-periodically disposed holes are randomly or non-periodically distributed across a portion of the fiber. Similar cross sections taken at different points along the length of the fiber will reveal different cross-sectional hole patterns, i.e., various cross sections will have different hole patterns, wherein the distributions of holes and sizes of holes do not match. That is, the voids or holes are non-periodic, i.e., they are not periodically disposed within the fiber structure. These holes are stretched (elongated) along the length (i.e. parallel to the longitudinal axis) of the optical fiber, but do not extend the entire length of the entire fiber for typical lengths of transmission fiber.

In some embodiments that cladding comprises periodically disposed holes. The multimode optical fiber disclosed herein exhibits very low bend induced attenuation, in particular very low macrobending. In some embodiments, high bandwidth is provided by low maximum relative refractive index in the core, and low bend losses are also provided.

For example, using the designs disclosed herein, fibers can been made which provide (a) a bandwidth of greater than 750 MHz-km, more preferably greater than 1.0 GHz-km, and even more preferably greater than 2.0 GHz-km, and most preferably greater than 3.0 GHz-km at a wavelength of 850 nm. These high bandwidths can be achieved while still maintaining a 1 turn 10 mm diameter mandrel wrap attenuation increase at a wavelength of 1550 nm, of less than 0.5 dB, more preferably less than 0.3 dB, and most preferably less than 0.2 dB. Similarly, these high bandwidths which exhibit such impressive bend performance at 1550 nm can also maintaining a 1 turn 10 mm diameter mandrel wrap attenuation increase at a wavelength of 850 nm of less than 1.5 dB, more preferably less than 1.0 dB, and most preferably less than 0.62 dB. Such fibers can also exhibit a 1 turn 10 mm diameter mandrel wrap attenuation increase at a wavelength of 1550 nm, in dB, of less than or equal to the product of two times (1/Δ1MAX)2.

In some embodiments, the core radius is large (e.g. greater than 20 μm), the core refractive index is low (e.g. less than 1.0%), and the bend losses are low. Preferably, the multimode optical fiber disclosed herein exhibits a spectral attenuation of less than 3 dB/km at 850 nm. We have also found that spinning the multimode fiber further improves the bandwidth for optical fiber having a cladding having holes. By spinning, we mean applying or imparting a spin to the fiber wherein the spin is imparted while the fiber is being drawn from an optical fiber preform, i.e. while the fiber is still at least somewhat heated and is capable of undergoing non-elastic rotational displacement and is capable of substantially retaining the rotational displacement after the fiber has fully cooled.

The numerical aperture (NA) of the optical fiber is preferably greater than the NA of the optical source directing signals into the fiber; for example, the NA of the optical fiber is preferably greater than the NA of a VCSEL source. The bandwidth of the multimode optical fiber varies inversely with the square of Δ1MAX. For example, a multimode optical fiber with Δ1MAX of 0.5% can yield a bandwidth 16 times greater than an otherwise identical multimode optical fiber except having a core with Δ1MAX of 2.0%.

In some embodiments, the core extends radially outwardly from the centerline to a radius R1, wherein 12.5≦R1≦40 microns. In some embodiments, 25≦R1≦32.5 microns, and in some of these embodiments, R1 is greater than or equal to about 25 microns and less than or equal to about 31.25 microns.

In some embodiments, the core has a maximum relative refractive index, less than or equal to 1.0%. In other embodiments, the core has a maximum relative refractive index, less than or equal to 0.5%.

In some embodiments, the optical fiber exhibits a 1 turn 10 mm diameter mandrel attenuation increase of no more than 1.0 dB, preferably no more than 0.5 dB, more preferably no more than 0.25 dB, even more preferably no more than 0.1 dB, and still more preferably no more than 0.05 dB, at all wavelengths between 800 and 1400 nm.

In a first aspect, multimode optical fiber is disclosed herein comprising a graded-index glass core, disposed about a longitudinal centerline, and a glass cladding surrounding the core. The cladding comprises an inner annular portion, a depressed-index annular portion, and an outer annular portion. The inner annular portion directly abuts the core, and the depressed-index annular portion directly abuts the inner annular region, and the inner annular portion has a relative refractive index profile having a maximum absolute magnitude, |Δ|, less than 0.05%. In some embodiments, the inner annular portion has a maximum relative refractive index profile, Δ2MAX, less than 0.05%.

In a second aspect, multimode optical fiber is disclosed herein comprising a graded-index glass core, disposed about a longitudinal centerline, and a glass cladding surrounding the core. The cladding comprises a depressed-index annular portion surrounding and in contact with the core, and an outer annular portion surrounding and in contact with the depressed-index annular portion.

Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

- Top of Page


FIG. 1 shows a schematic representation (not to scale) of the refractive index profile of a cross-section of the glass portion of an embodiment of a first aspect of multimode optical fiber disclosed herein wherein the depressed-index annular portion is offset from the core and is surrounded by an outer annular portion.

FIG. 2 is a schematic representation (not to scale) of a cross-sectional view of the optical waveguide fiber of FIG. 1.

FIG. 3 shows a schematic representation (not to scale) of the refractive index profile of a cross-section of the glass portion of an embodiment of a first aspect of multimode optical fiber disclosed herein wherein the depressed-index annular portion is offset from the core and the depressed-index annular portion extends to the outermost periphery.

FIG. 4 is a schematic representation (not to scale) of a cross-sectional view of the optical waveguide fiber of FIG. 3.

FIG. 5 shows a schematic representation (not to scale) of the refractive index profile of a cross-section of the glass portion of an embodiment of a second aspect of multimode optical fiber disclosed herein wherein the depressed-index annular portion is directly adjacent to the core.

FIG. 6 is a schematic representation (not to scale) of a cross-sectional view of the optical waveguide fiber of FIG. 5.

FIG. 7 shows the measured 1×10 mm macrobend attenuation increase at various wavelengths for Examples 1-3.

FIG. 8 shows the measured 1×10 mm macrobend attenuation increase at various wavelengths for Examples 4-5.

FIG. 9 shows the measured 1×10 mm macrobend attenuation increase at various wavelengths for Examples 6-8.

DETAILED DESCRIPTION

- Top of Page


Additional features and advantages of the invention will be set forth in the detailed description which follows and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described in the following description together with the claims and appended drawings.

The “refractive index profile” is the relationship between refractive index or relative refractive index and waveguide fiber radius.

The “relative refractive index percent” is defined as Δ %=100×(ni2−nREF2)/2ni2, where ni is the maximum refractive index in region i, unless otherwise specified. The relative refractive index percent is measured at 850 nm unless otherwise specified. In the first aspect, the reference index nREF is the refractive index at the core/clad interface. In the second aspect, nREF is the average refractive index of the outer annular portion of the cladding, which can be calculated, for example, by taking “N” index measurements (nC1, nC2, . . . nCN) in the outer annular portion of the cladding, and calculating the average refractive index by:

n C = ( 1 / N )  ∑ i = 1 i = N  n Ci .

As used herein, the relative refractive index is represented by Δ and its values are given in units of “%”, unless otherwise specified. In cases where the refractive index of a region is less than the reference index nREF, the relative index percent is negative and is referred to as having a depressed region or depressed-index, and the minimum relative refractive index is calculated at the point at which the relative index is most negative unless otherwise specified. In cases where the refractive index of a region is greater than the reference index nREF, the relative index percent is positive and the region can be said to be raised or to have a positive index. An “updopant” is herein considered to be a dopant which has a propensity to raise the refractive index relative to pure undoped SiO2. A “downdopant” is herein considered to be a dopant which has a propensity to lower the refractive index relative to pure undoped SiO2. An updopant may be present in a region of an optical fiber having a negative relative refractive index when accompanied by one or more other dopants which are not updopants. Likewise, one or more other dopants which are not updopants may be present in a region of an optical fiber having a positive relative refractive index. A downdopant may be present in a region of an optical fiber having a positive relative refractive index when accompanied by one or more other dopants which are not downdopants. Likewise, one or more other dopants which are not downdopants may be present in a region of an optical fiber having a negative relative refractive index.

Macrobend performance was determined according to FOTP-62 (IEC-60793-1-47) by wrapping 1 turn around a either a 10 mm or 20 mm diameter mandrel (the “1×10 mm diameter macrobend loss” or the “1×20 mm diameter macrobend loss”) and measuring the increase in attenuation due to the bending using an overfilled launch condition. For a fiber with low macrobend loss, the measurement is done by wrapping multiple turns on a mandrel to increase the accuracy. The macrobend loss is normalized to 1 turn/m by dividing the total loss by the number of wraps around the mandrel. Bandwidth was measured according to FOTP-204 with overfilled launch, except as noted. In some cases bandwidth can be measured using a restricted mode launch (RML). In these cases, the optical signal is only launched into the core of the test fiber. RML can be accomplished by using an optical source with a spot size of less than or equal to the diameter of the core of the test fiber. For example, 1) using a light restricting aperture, 2) a light emitting diode or laser source with a spot size less than or equal to the test core diameter, or 3) using light from a conventional multimode fiber (without a depressed cladding) with the core size less than or equal to the test fiber core size. In some cases, by using restricted mode launch conditions, the RML bandwidth (e.g., measured at 850 nm or 1300 nm) for multimode fibers containing a depressed cladding can be higher than the bandwidth for these fibers when measured using overfilled launch. For example, some fibers can have greater than 1 GHz-Km bandwidth at 850 nm using a restricted mode launch while they have a bandwidth of less than 750 MHz-Km when tested using an overfilled launch.

The term “α-profile” or “alpha profile” refers to a relative refractive index profile, expressed in terms of Δ(r) which is in units of “%”, where r is radius, which follows the equation,


Δ(r)=Δ(ro)(1−[|r−ro|/(r1−ro)]α),




← Previous       Next → Advertise on FreshPatents.com - Rates & Info


You can also Monitor Keywords and Search for tracking patents relating to this Bend resistant multimode optical fiber patent application.
###
monitor keywords

Keyword Monitor How KEYWORD MONITOR works... a FREE service from FreshPatents
1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored.
3. Each week you receive an email with patent applications related to your keywords.  
Start now! - Receive info on patent apps like Bend resistant multimode optical fiber or other areas of interest.
###


Previous Patent Application:
Optical fiber fusion splicer
Next Patent Application:
Cable management system with twist latch
Industry Class:
Optical waveguides
Thank you for viewing the Bend resistant multimode optical fiber patent info.
- - -

Results in 0.02246 seconds


Other interesting Freshpatents.com categories:
Nokia , SAP , Intel , NIKE ,

###

Data source: patent applications published in the public domain by the United States Patent and Trademark Office (USPTO). Information published here is for research/educational purposes only. FreshPatents is not affiliated with the USPTO, assignee companies, inventors, law firms or other assignees. Patent applications, documents and images may contain trademarks of the respective companies/authors. FreshPatents is not responsible for the accuracy, validity or otherwise contents of these public document patent application filings. When possible a complete PDF is provided, however, in some cases the presented document/images is an abstract or sampling of the full patent application for display purposes. FreshPatents.com Terms/Support
-g2-0.1509

66.232.115.224
Next →
← Previous
     SHARE
     

stats Patent Info
Application #
US 20100272406 A1
Publish Date
10/28/2010
Document #
12830826
File Date
07/06/2010
USPTO Class
385124
Other USPTO Classes
International Class
02B6/028
Drawings
6


Your Message Here(14K)



Follow us on Twitter
twitter icon@FreshPatents



Optical Waveguides   Optical Fiber Waveguide With Cladding   With Graded Index Core Or Cladding  

Browse patents:
Next →
← Previous