Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/02—Optical fibres with cladding with or without a coating
  • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
  • G02B6/0288—Multimode fibre, e.g. graded index core for compensating modal dispersion
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
  • C03B37/01—Manufacture of glass fibres or filaments
  • C03B37/012—Manufacture of preforms for drawing fibres or filaments
  • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
  • C03B37/01413—Reactant delivery systems
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/02—Optical fibres with cladding with or without a coating
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/02—Optical fibres with cladding with or without a coating
  • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2201/00—Type of glass produced
  • C03B2201/06—Doped silica-based glasses
  • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
  • C03B2201/31—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with germanium
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2203/00—Fibre product details, e.g. structure, shape
  • C03B2203/10—Internal structure or shape details
  • C03B2203/22—Radial profile of refractive index, composition or softening point
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2203/00—Fibre product details, e.g. structure, shape
  • C03B2203/10—Internal structure or shape details
  • C03B2203/22—Radial profile of refractive index, composition or softening point
  • C03B2203/26—Parabolic or graded index [GRIN] core profile
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2203/00—Fibre product details, e.g. structure, shape
  • C03B2203/30—Polarisation maintaining [PM], i.e. birefringent products, e.g. with elliptical core, by use of stress rods, "PANDA" type fibres
  • C03B2203/31—Polarisation maintaining [PM], i.e. birefringent products, e.g. with elliptical core, by use of stress rods, "PANDA" type fibres by use of stress-imparting rods, e.g. by insertion
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2203/00—Fibre product details, e.g. structure, shape
  • C03B2203/36—Dispersion modified fibres, e.g. wavelength or polarisation shifted, flattened or compensating fibres (DSF, DFF, DCF)
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
  • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

• the present invention relates generally to a multimode optical fiber and method for use with telecommunication systems employing low data rates, as well as systems employing high data rates, and more particularly, to a multimode optical fiber and method optimized for applications designed for state of the art laser sources, as well as common light emitting diode sources. While the present invention is subject to a wide range of applications, it is particularly well suited for use in telecommunications systems designed to transmit data at rates equal to and exceeding one gigabit/sec. 2.
• the goal of the telecommunication industry is generally to transmit greater amounts of information, over longer distances, in shorter periods of time. Over time, it has been shown that this objective is a moving target with no apparent end in sight. As the number of systems users and frequency of system use increase, demand for system resources increases as well.
• Multimode optical fiber currently employed in telecommunication systems is designed primarily for use with LED sources and is generally not optimized for use with the lasers envisioned to operate in systems designed to transmit information at rates equal to or greater than one (1 ) gigabit/sec.
• Laser sources place different demands on multimode fiber quality and design, compared to LED sources.
• the index profile at the core of multimode fibers has been tuned to produce high bandwidth with LED sources, which tend to overfill the core. The combination of the light intensity distribution from the LED source input pulse and the index profile of the fiber produces an overfilled modal weighting that results in an output pulse that has a relatively smooth rise and fall.
• a typical campus layout for a LAN system is designed to meet certain specified link lengths.
• the standard for the campus backbone (which travels between buildings) typically has a link length of up to about 2 km.
• the building backbone or riser (which travels between floors of a building)typically has a link length of up to about 500 meters.
• the horizontal link length (which travels between offices on a floor of a building) typically has a link length of up to about 100 meters.
• Older and current LAN technology, such as 10 Megabit Ethernet can achieve a 2 km link length transmission with standard grade multimode optical fiber. However, next generation systems capable of gigabit/sec. and higher transmission rates cannot achieve all of these link lengths with standard multimode fiber presently available.
• standard multimode fiber In the 850nm window, standard multimode fiber is limited to a link length of approximately 220 meters. In the 1300nm window, standard grade fiber is limited to a link length of only about 550 meters. Accordingly, present technology only enables, at most, coverage for about two of the three campus link lengths. To fully enable a LAN for gigabit/sec. transmission rates, a multimode fiber capable of transmitting information over each of the three link lengths is necessary.
• overfilled (OFL) bandwidth is defined as the bandwidth using the standard measurement technique described in EIA/TIA 455-51
• FOTP-51 A "Pulse Distortion Measurement of Multimode Glass Optical Fiber Information Transmission Capacity", with launch conditions defined by EIA/TIA 455-54A FOTP-54 "Mode Scrambler Requirements for Overfilled Launching Conditions to Multimode Fibers".
• laser bandwidth is defined as and measured using the standard measurement technique described in EIA/TIA 455-51A FOTP-51 and either of the following two launch conditions methods. Method (a) is used to determine the 3 dB bandwidth at 1300, and method (b) is used to determine the 3dB bandwidth at 850 nm.
• Method (a) which is used to determine the 3dB laser bandwidth at 1300 nm, utilizes a 4 nm RMS spectral width 1300nm laser with a category 5 coupled power ratio launch modified by connection of a 2 meter, standard step index, single-mode fiber, patch-cord wrapped twice around a 50 mm diameter mandrel.
• the launch condition is further modified by mechanically offsetting the central axis of the singlemode fiber from that of the multimode fiber in such a manner that a 4 um lateral offset between the central axis of the core of the single mode fiber patch-cord and the multimode fiber under test is created.
• the refractive index profile can be adjusted to result in OFL bandwidth of lOOOMHz.km at 850nm and 300MHz.km at 1300nm, or it can be adjusted to result in OFL bandwidth of 250MHz.km at 850nm and 4000MHz.km at 1300nm.
• multimode optical waveguide fibers having standard "alpha" profiles, however, it is not possible to achieve an OFL bandwidth of lOOOMHz.km at 850nm and 4000MHz.km at 1300nm.
• the present invention is directed to a multimode optical fiber that is optimized for high speed laser sources capable of 1.0, 2.5, and 10 gigabit per second data transmission while exceeding the link length requirements discussed above. Moreover, the same multimode optical fiber maintains sufficiently high OFL bandwidth to support the transmission of information with the 1300nm and 850nm LED sources presently used in LAN systems. Such a multimode optical fiber will enable current LAN system owners to maintain their present LED based LAN systems, while at the same time enable them to easily transfer to a "Gigabit Ethernet System" without having to undertake a costly multimode fiber upgrade.
• gigabit Ethernet System is defined as a telecommunication system, such as a LAN, which is capable of transmitting data at rates equal to and/or exceeding one (1 ) gigabit/sec. Accordingly, one aspect of the present invention relates a multimode fiber having a first laser bandwidth greater than 220MHz.km in the 850nm window, a second laser bandwidth greater than ⁇ OOMHz.km in the 1300nm window, a first OFL bandwidth of at least 160MHz.km in the 850nm window, and a second OFL bandwidth of at least ⁇ OOMHz.km in the 1300nm window.
• Such a multimode optical fiber has a variety of uses in the telecommunication industry, and is particularly well suited for use in telecommunication systems employing high speed laser sources. Such a fiber has the added benefit of providing sufficient OFL bandwidth for LED sources presently used in LAN systems.
• the invention is directed to a multimode transmission system capable of transmitting data at rates equal to and exceeding one gigabit/sec.
• the multimode transmission system includes a laser source which transmits at least one gigabit/second of information, and a multimode optical fiber communicating with the laser source.
• the multimode optical fiber has a first laser bandwidth of at least 385MHz.km in the 8 ⁇ 0nm window which is capable of carrying the information at least ⁇ OO meters.
• the multimode optical fiber also has a second laser bandwidth of at least 746MHz.km in the 1300nm window for carrying the information at least 1000 meters.
• the multimode optical fiber includes first and second OFL bandwidths sufficiently high to be used with ⁇ Onm and 1300nm LED sources.
• Another aspect of the present invention relates to a multimode optical fiber having a 62. ⁇ m core, and a cladding bounding the core.
• the slope of the first region is preferably greater than the slope of the second region. More preferably, the slope of the first region is greater than 1. ⁇ times the slope of the second region.
• the present invention is directed to a method of forming a multimode optical fiber.
• the method includes the steps of thermochemically reacting a silica containing precursor reactant and at least one dopant reactant to form soot, and delivering the soot to a target in a 5 manner sufficient to produce a glass preform having specified characteristics.
• the glass preform is drawn into a multimode optical fiber having a 62.5 ⁇ m core region and a cladding region bounding the core region.
• the multimode optical fiber of the present invention results in a number ⁇ of advantages over other multimode optical fibers known in the art.
• One such advantage is that the multimode optical fiber of the present invention is fully compatible for use with high speed laser sources, as well as LED sources. Accordingly, the multimode optical fiber of the present invention can be used with conventional local area networks employing LED sources, and can be 0 used with Gigabit Ethernet Systems, which employ high speed laser sources.
• the multimode optical fiber of the present invention eliminates the need for costly mode conditioning patch cords often used to enable operation in the 1300nm operating window for Gigabit Ethernet System protocol.
• a mode conditioning patch cord is ⁇ used to move power away from the center of the multimode fiber in order to avoid center line profile defects which typically result from some manufacturing processes.
• the preferred multimode optical fiber of the present invention is manufactured using the Outside Vapor Deposition process (OVD)
• the preferred multimode optical fiber of the present invention has reduced 0 centeriine profile defects. Accordingly, a mode conditioning patch cord is no longer needed to enable operation in the 1300nm operating window of the preferred fiber of the present invention, thus allowing for on-center launch or slightly off-set due to loose connector tolerances, resulting in ease of installation and use.
• the multimode optical fiber of the present invention optimizes laser performance with a variety of laser sources, such as, but not limited to, ⁇ 780nm Fabry-Perot lasers, ⁇ Onm Vertical Cavity Surface Emitting Lasers
• the multimode optical fiber of the present invention is also designed to support operation at 2. ⁇ and 10 gigabits/second over significant link lengths when used with high performance lasers in more 0 advanced telecommunication systems.
• Fig. 1 is a perspective view of a preferred embodiment of a multimode optical fiber of the present invention.
• Fig. 2 is a DMD profile curve of the multimode optical fiber of Fig. 1 measured at 1300nm.
• 0 Fig. 3 is a DMD profile curve of the multimode optical fiber of Fig. 1 measured at 8 ⁇ 0nm.
• Fig. 4 is a DMD profile curve of a second preferred embodiment of a multimode optical fiber of the present invention measured at 1300nm.
• Fig. ⁇ is a graph showing the DMD profile curve of the multimode optical fiber of Fig.1 , and the DMD profile curve for a second preferred multimode optical fiber measured at 1300nm.
• Fig. 6 shows the bandwidth of the optical fiber of Fig. 1 for a variety of laser sources.
• Fig. 7 is the refractive index profile curve of the first preferred embodiment of the multimode optical fiber of the present invention, which has the DMD profile of Fig.2.
• Fig. 8 is the refractive index profile curve of the second preferred embodiment of the multimode optical fiber of the present invention, which has the DMD profile of Fig. 4.
• a refractive index profile for a multimode optical fiber is disclosed, which is optimized both for applications using state of the art laser sources, as well as the more common LED sources.
• Alpha index of refraction profiles describe a profile shape which may vary continuously with radius.
• the refractive index profile preferably includes at least two regions having at least "alpha" exponents, commonly referred to by the symbol ( ⁇ ), such that the index profile changes smoothly from an alpha or alphas optimized for one or more laser sources (at one or more wavelengths) near the center of the profile to an alpha or alphas optimized for LEDs (at one or more wavelengths) near the outside of the profile.
• a multimode optical fiber having such an index profile extends both distance and data rate capability beyond that documented for telecommunication systems capable of delivering information at rates equal to and exceeding one (1 ) gigabit/sec. Because laser sources have smaller "spots" than LEDs, it has been found that the outer portion of the profile can be optimized according to OFL bandwidth requirements (typically 160-200MHz.km at ⁇ Onm and ⁇ OO+MHz.km at 1300nm, for multimode fibers having 62. ⁇ um cores), while simultaneously optimizing the inner portion of the profile for laser bandwidth requirements and source characteristics. It is believed that this is the first profile which is simultaneously optimized for both large spot LEDs and small spot lasers at both the 1300nm and ⁇ Onm windows.
• the inner profile requirements are preferably determined by the SX bandwidth requirements. It has been found that high laser bandwidth at both short wavelength (for example, with selected 780nm CD lasers or ⁇ Onm VCSELs), and long wavelength (for example, with 1300nm or 1 ⁇ 00nm Fabry-Perot single mode 0 lasers) can be achieved when the inner profile is correctly optimized.
• index profile provides high 1300nm OFL bandwidth with LED sources so that the adjustment to the overall profile to achieve superior performance with lasers is small and/or in areas of the profile not affecting OFL bandwidth performance.
• ⁇ requires that alpha(r) be a smooth function of r, without abrupt transitions.
• the present invention is directed to a multimode optical fiber having an index profile specifically designed to provide high bandwidth and low temporal jitter with typical short wavelength (for example, 730, 8 ⁇ 0, or 980nm) lasers and long wavelength (for example, 1300nm or 1 ⁇ 00nm) lasers while maintaining 0 sufficiently high bandwidth and low jitter when used with legacy, 1300nm and
• the index profile of the multimode optical fiber of the present invention can be described in a number of ways.
• the OFL or laser bandwidth is determined from the amplitude of the Fourier transform of P ou t(t) and is optimized if all ⁇ m are equal.
• the mode delays ⁇ m are determined by the index profile and the wavelength of operation.
• the modal power P m depends on the characteristics 0 of the source (the specific laser, LED, etc.).
• the multimode fibers of the present invention are preferably designed to meet the OFL or laser bandwidth requirements for a majority of, and most preferably all, of the commonly used sources.
• the fiber requirements might be that the OFL bandwidth be greater than 160MHz.km and ⁇ OO MHz.km with 8 ⁇ 0nm and 1300nm LED sources, respectively, and that the laser bandwidth be greater than 38 ⁇ MHz.km and 746MHz.km with 850nm VCSEL and 1300nm Fabry-Perot laser sources, 5 respectively.
• a second way of describing the fiber's index profile relates to direct measurement of the index of refraction or the germania content of the core.
• Typical multimode fibers are designed to a have an index of refraction that varies as a function of radial position and is proportional to the germania 0 content.
• This index profile, n(r) is described by the following function:
• n(r) m (1 - 2 ⁇ (r/a) 9 ) 05
• ni is the index value at the center of the core
• r is the radial position
• a is ⁇ the radius of the core clad interface
• g is the profile shape parameter
• ⁇ is defined as:
• n 0 is the index value at the core-clad interface.
• index profile is defined as ⁇ follows:
• n(r) rv, (1 - 2 ⁇ (r/a) 9(r) ) 0 5
• g(r) is a profile shape parameter which changes continuously with radius 0 so that the OFL and laser bandwidth objectives described above in the first method of describing the index profile are met.
• the relative power of modes near the center is greater for the laser sources than for the LED sources, and greater for the long wavelength lasers (for example, 1300nm Fabry-Perot laser) than for the short wavelength laser sources (for example, the typical ⁇ Onm VCSEL sources).
• the long wavelength lasers for example, 1300nm Fabry-Perot laser
• the short wavelength laser sources for example, the typical ⁇ Onm VCSEL sources.
• g(r) In practice, it is adequate for g(r) to vary from a larger value (equalizing mode delays closer to 780- ⁇ Onm) near the center to a lower value (equalizing closer to 1300nm) at the outside. In practice g(r) never intentionally passes below the value appropriate for 1300nm. It is important for the OFL bandwidth that g(r) 0 vary smoothly and continuously.
• Such an index profile with a varying g(r) can perhaps be visualized most easily with a third method for describing index profiles.
• This method uses what are known to those skilled in the art, as Differential Mode Delay (DMD) measurements.
• DMD Differential Mode Delay
• the method briefly described, involves scanning a pulse from ⁇ a single mode optical fiber radially across the multimode fiber core, and measuring the output pulse and mean delay time for pulses launched at different outset positions with respect to the core of the multimode fiber.
• the pulse delays are plotted as a function of radial position, and the local slope of the DMD vs. (r/a) 2 , where "r" is defined as the radial offset of the single mode 0 fiber relative to the center of the multimode core (i.e.
• the OFL and laser bandwidth of a number of fibers with different refractive index profiles are measured, and fibers which achieve high bandwidth 5 with both laser and LED sources are identified.
• the DMD of these optimum fibers characterize the desired or target profile for duplication in additional multimode optical fibers. This empirical procedure using the DMD does not characterize the P m of the different sources. Rather, it serves to characterize the fiber which works with the sources.
• a key aspect of the present invention is that laser intensity distributions are generally much smaller than LEDs. For that reason, among others, it is possible to optimize the fiber index profile for both laser and LED operation.
• the outer portion of the index profile is optimized for 1300nm LED, thereby ensuring good ⁇ performance, i.e. OFL bandwidth greater than ⁇ OO MHz.km, for legacy systems.
• the inner portion of the index profile is optimized to provide more equal laser bandwidth at 1300nm and ⁇ Onm.
• FIG. 1 An ⁇ exemplary embodiment of the multimode optical fiber of the present invention is shown in Figure 1 , and is designated generally throughout by reference numeral 10.
• Preferred multimode optical fiber 10 is a 62.5 ⁇ m multimode optical fiber optimized to have a first laser bandwidth greater than 220MHz.km at 850nm, 0 and a second laser bandwidth greater than ⁇ OOMHz.km at 1300nm. It will be understood by those skilled in the art, however, that multimode fibers in accordance with the present invention have been made which likely have similarly large bandwidths across the 8 ⁇ 0 and 1300 nm operating windows, i.e., between about 810nm and 890nm, more preferably 830nm and 870nm, and between about 1260nm and 1340nm, more preferably between about 1280nm and 1320nm.
• preferred multimode optical fiber 10 includes a first OFL bandwidth of at least 160MHz.km in the 8 ⁇ 0nm window, and a second OFL bandwidth of at least ⁇ OOMHz.km in the 1300nm window. More preferably, however, multimode optical fiber 10 has a 62. ⁇ m core 12 and is designed for a minimum laser bandwidth of 38 ⁇ MHz.km at 8 ⁇ 0 nm, and a minimum laser 0 bandwidth of 746MHz.km at 1300nm. It should be noted that the 1300nm laser bandwidth mentioned above and described throughout the entirety of this specification, should preferably be measured with a 1300nm laser meant for use with standard single mode fiber.
• the laser launch at 1300nm is measured with the majority of the power being launched along the central axis of the multimode fiber. This obviates the need for such mode conditioning patch 0 cords, thereby reducing system implementation, cost, and complexity.
• the minimum laser bandwidth is preferably ⁇ OOMHz.km in the short wavelength window and 1684MHz.km in the long wavelength window.
• multimode optical fiber 10 having the 62. ⁇ rn core 12 can carry at least one gigabit/sec of information over a link length of at least ⁇ OOm in the short wavelength, and over a link length of 1000m in the long wavelength. These distances are increased to link lengths of over 600m and 2000m, 0 respectively, for a ⁇ O ⁇ m core multimode optical fiber.
• preferred multimode optical fiber 10 is not limited to the one gigabit/sec transmission rate. Rather, the present invention is capable of data rate transmission in excess of ten (10) gigabits/sec over significant link lengths.
• DMD measurement curves indicative of 62.5 ⁇ m core multimode optical fibers having properties sufficient to meet the above- described operating parameters are depicted in Figs. 2 through ⁇ .
• Fig. 2 shows a DMD measurement curve 20 of a multimode optical fiber
• DMD curve is slightly rising, the index profile is optimized for a wavelength slightly less than 8 ⁇ 0nm, and in the region where the DMD curve slopes down, it indicates an index profile is optimized for a wavelength greater than ⁇ Onm.
• DMD profiles 20 and 40 are both shown in the same graph in Fig. ⁇ measured at 1300nm.
• the slope of the first region is at least 1. ⁇ times greater than the slope of the second region.
• the preferred method of forming a multimode optical fiber in accordance with the present invention and having the above-described target DMD profile includes the steps of thermochemically reacting a silica containing precursor reactant and at least one dopant reactant to form soot, delivering the soot to a target in a manner sufficient to produce a glass preform having specified ⁇ characteristics, and drawing the glass preform into a multimode optical fiber having a 62. ⁇ m or ⁇ Oum core region.
• the reacting step further includes selecting the precursor reactant and at least one dopant reactant according to a soot deposition recipe sufficient to result in a multimode optical fiber that exhibits the characteristics of the target DMD profile.
• the soot deposition recipe includes the required proportions of
• Fig. 7 shows the substantially parabolic refractive index profile curve of 0 the first preferred embodiment of the multimode optical fiber of the present invention (the same fiber that exhibits the DMD profile curve of Fig.2 and 3).
• Fig. 8 shows the substantially parabolic refractive index profile curve of the second preferred embodiment of the multimode optical fiber of the present invention (the same fiber that exhibits the DMD profile of Fig. 4).
• Example 1 ⁇ One method of testing the performance of the laser optimized multimode fiber is to manufacture a fiber having the desired DMD characteristics and test it with a variety of laser sources. The results of such testing are shown in Fig. 6.
• the 'effective' bandwidth (MHz.km) of the multimode optical fiber 0 characterized by the DMD profile depicted in Figs. 2-3 and 7 is shown in Fig. 6 for a variety of 730 to ⁇ Onm Gigabit Ethernet System lasers.
• the fiber's overfilled (OFL) bandwidth measured using the standard measurement and launch techniques referenced earlier in this application, was 28 ⁇ MHz.km at ⁇ Onm and 1064 MHz.km at 1300nm.
• the fiber's laser bandwidth measured using the standard measurement and launch techniques referenced earlier in this application was 930MHz.km at ⁇ Onm (using the patchcord with a 23. ⁇ um diameter core as well as a ⁇ Onm source laser with an RMS spectral width less than O. ⁇ nm, as described earlier) and 202 ⁇ MHz.km at 1300nm (using a Fabry-Perot laser typical for single mode fiber applications and a patchcord ensuring a launch offset 4um from the center of the core).
• the 'effective' bandwidths shown in figure 6 for various Gigabit Ethernet System laser sources are measured with the same measurement technique as the defined ⁇ Onm laser bandwidth with a 23.5um patchcord, but with a launch condition that varies with each individual Gigabit Ethernet System laser because each laser has a different distribution of power, both in the near field and in the far field.
• the measured laser bandwidth with the defined launch (930MHz.km) is approximately the same as obtained with a number of actual Gigabit Ethernet Systemlasers.
• the short wavelength Gigabit Ethernet System laser bandwidths are all clearly superior to the ⁇ Onm OFL bandwidth of 2 ⁇ MHz.km and in the range required to significantly extend Gigabit Ethernet System link lengths.
• the 1300nm laser bandwidth measured using a 1300nm Fabry-Perot laser with a 4um offset was more than double that of the 1300nm OFL bandwidth.
• the fiber whose measured DMD is in figure 4 and whose measured index profile is in figure ⁇ was tested for OFL bandwidth, for 'defined' laser bandwidth using the 23. ⁇ um patchcord at ⁇ Onm and the 4um offset at 1300nm, and for 'effective' bandwidth with a set of 13 Gigabit Ethernet System lasers.
• the standard OFL bandwidth was measured at ⁇ 64MHz.km at ⁇ Onm and 560MHz.km at 1300nm.
• the 'defined' laser bandwidth at ⁇ Onm using the patchcord with a 23. ⁇ um diameter core was 326MHz.km, while at 1300nm the laser bandwidth defined by using a Fabry-Perot laser with a 4um offset had a value of ⁇ 279MHz.km.
• the 'effective' bandwidths measured with 13 Gigabit Ethernet System lasers at ⁇ Onm or 780nm were as follows: 1214, ⁇ 6, ⁇ 0, ⁇ 76, 792, 7 ⁇ 6, 764, 726, 614, 394, 376, 434 and 472 MHz.km.
• the defined laser launch for ⁇ Onm with a patchcord with a 23. ⁇ um diameter core yields a bandwidth which approximates the 'effective' bandwidth seen with a number of actual Gigabit Ethernet laser sources.

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• 2000
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  • 2000-02-22 KR KR1020017010691A patent/KR100609438B1/ko not_active IP Right Cessation
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  • 2000-02-22 CN CN00804063A patent/CN1341223A/zh active Pending
  • 2000-02-22 EP EP00908747A patent/EP1153323A4/en not_active Withdrawn
• 2001
  • 2001-07-17 ZA ZA200105863A patent/ZA200105863B/en unknown
• 2010
  • 2010-08-05 JP JP2010176289A patent/JP2010286850A/ja active Pending

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